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  • 1.
    Abdalla, Ahmed
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Determination of a gravimetric geoid model of Sudan using the KTH method2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main objective of this study is to compute a new gravimetric geoid model of Sudan

    using the KTH method based on modification of Stokes’ formula for geoid determination.

    The modified Stokes’ formula combines regional terrestrial gravity with long-wavelength

    gravity information provided by the global gravitational model (GGM). The collected

    datasets for this study contained the terrestrial gravity measurements, digital elevation

    model (DEM), GPS/levelling data and four global gravitational Models (GGMs), (EGM96,

    EIGEN-GRACE02S, EIGEN-GL04C and GGM03S).

    The gravity data underwent cross validation technique for outliers detection, three gridding

    algorithms (Kriging, Inverse Distance Weighting and Nearest Neighbor) have been tested,

    thereafter the best interpolation approach has been chosen for gridding the refined gravity

    data. The GGMs contributions were evaluated with GPS/levelling data to choose the best

    one to be used in the combined formula.

    In this study three stochastic modification methods of Stokes’ formula (Optimum, Unbiased

    and Biased) were performed, hence an approximate geoid height was computed. Thereafter,

    some additive corrections (Topographic, Downward Continuation, Atmospheric and Ellipsoidal)

    were added to the approximated geoid height to get corrected geoid height.

    The new gravimetric geoid model (KTH-SDG08) has been determined over the whole

    country of Sudan at 5′ x 5′ grid for area ( 4 ). The optimum method

    provides the best agreement with GPS/levelling estimated to 29 cm while the agreement for

    the relative geoid heights to 0.493 ppm. A comparison has also been made between the new

    geoid model and a previous model, determined in 1991 and shows better accuracy.

    􀁄 ≤φ ≤ 23􀁄 , 22􀁄 ≤ λ ≤ 38􀁄

    Keywords: geoid model, KTH method, stochastic modification methods, modified Stokes’ formula,

    additive corrections.

  • 2.
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Recovering Moho parameters using gravimetric and seismic data2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Isostasy is a key concept in geoscience to interpret the state of mass balance between the Earth’s crust and mantle. There are four well-known isostatic models: the classical models of Airy/Heiskanen (A/H), Pratt/Hayford (P/H), and Vening Meinesz (VM) and the modern model of Vening Meinesz-Moritz (VMM). The first three models assume a local and regional isostatic compensation, whereas the latter one supposes a global isostatic compensation scheme.

    A more satisfactory test of isostasy is to determine the Moho interface. The Moho discontinuity (or Moho) is the surface, which marks the boundary between the Earth’s crust and upper mantle. Generally, the Moho interface can be mapped accurately by seismic observations, but limited coverage of seismic data and economic considerations make gravimetric or combined gravimetric-seismic methods a more realistic technique for imaging the Moho interface either regional or global scales.

    It is the main purpose of this dissertation to investigate an isostatic model with respect to its feasibility to use in recovering the Moho parameters (i.e. Moho depth and Moho density contrast). The study is mostly limited to the VMM model and to the combined approach on regional and global scales. The thesis briefly includes various investigations with the following specific subjects:

    1) to investigate the applicability and quality of satellite altimetry data (i.e. marine gravity data) in Moho determination over the oceans using the VMM model, 2) to investigate the need for methodologies using gravimetric data jointly with seismic data (i.e. combined approach) to estimate both the Moho depth and Moho density contrast over regional and global scales, 3) to investigate the spherical terrain correction and its effect on the VMM Moho determination, 4) to investigate the residual isostatic topography (RIT, i.e. difference between actual topography and isostatic topography) and its effect in the VMM Moho estimation, 5) to investigate the application of the lithospheric thermal-pressure correction and its effect on the Moho geometry using the VMM model, 6) Finally, the thesis ends with the application of the classical isostatic models for predicting the geoid height.

    The main input data used in the VMM model for a Moho recovery is the gravity anomaly/disturbance corrected for the gravitational contributions of mass density variation due in different layers of the Earth’s crust (i.e. stripping gravity corrections) and for the gravity contribution from deeper masses below the crust (i.e. non-isostatic effects). The corrections are computed using the recent seismic crustal model CRUST1.0.

    Our numerical investigations presented in this thesis demonstrate that 1) the VMM approach is applicable for estimating Moho geometry using a global marine gravity field derived by satellite altimetry and that the possible mean dynamic topography in the marine gravity model does not significantly affect the Moho determination, 2) the combined approach could help in filling-in the gaps in the seismic models and it also provides good fit to other global and regional models more than 90 per cent of the locations, 3) despite the fact that the lateral variation of the crustal depth is rather smooth, the terrain affects the Moho result most significantly in many areas, 4) the application of the RIT correction improves the agreement of our Moho result with some published global Moho models, 5) the application of the lithospheric thermal-pressure correction improves the agreement of VMM Moho model with some other global Moho models, 6) the geoid height cannot be successfully represented by the classical models due to many other gravitational signals from various mass variations within the Earth that affects the geoid.  

  • 3.
    Abrehdary, Majid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Univ Karlstad, Sweden.
    Sjöberg, L. E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Univ Gavle, Sweden.
    Sampietro, D.
    Towards the Moho depth and Moho density contrast along with their uncertainties from seismic and satellite gravity observations2017In: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 11, no 4, p. 231-247Article in journal (Refereed)
    Abstract [en]

    We present a combined method for estimating a new global Moho model named KTH15C, containing Moho depth and Moho density contrast (or shortly Moho parameters), from a combination of global models of gravity (GOCO05S), topography (DTM2006) and seismic information (CRUST1.0 and MDN07) to a resolution of 1 degrees x 1 degrees based on a solution of Vening Meinesz-Moritz' inverse problem of isostasy. This paper also aims modelling of the observation standard errors propagated from the Vening Meinesz-Moritz and CRUST1.0 models in estimating the uncertainty of the final Moho model. The numerical results yield Moho depths ranging from 6.5 to 70.3 km, and the estimated Moho density contrasts ranging from 21 to 650 kg/m(3), respectively. Moreover, test computations display that in most areas estimated uncertainties in the parameters are less than 3 km and 50 kg/m(3), respectively, but they reach to more significant values under Gulf of Mexico, Chile, Eastern Mediterranean, Timor sea and parts of polar regions. Comparing the Moho depths estimated by KTH15C and those derived by KTH11C, GEMMA2012C, CRUST1.0, KTH14C, CRUST14 and GEMMA1.0 models shows that KTH15C agree fairly well with CRUST1.0 but rather poor with other models. The Moho density contrasts estimated by KTH15C and those of the KTH11C, KTH14C and VMM model agree to 112, 31 and 61 kg/m(3) in RMS. The regional numerical studies show that the RMS differences between KTH15C and Moho depths from seismic information yields fits of 2 to 4 km in South and North America, Africa, Europe, Asia, Australia and Antarctica, respectively.

  • 4.
    Abrehdary, Majid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Univ Gavle, Dept Ind Dev IT & Land Management, SE-80176 Gavle, Sweden.
    Combined Moho parameters determination using CRUST1.0 and Vening Meinesz-Moritz model2015In: Journal of Earth Science, ISSN 1674-487X, E-ISSN 1867-111X, Vol. 26, no 4, p. 607-616Article in journal (Refereed)
    Abstract [en]

    According to Vening Meinesz-Moritz (VMM) global inverse isostatic problem, either the Moho density contrast (crust-mantle density contrast) or the Moho geometry can be estimated by solving a non-linear Fredholm integral equation of the first kind. Here solutions to the two Moho parameters are presented by combining the global geopotential model (GOCO-03S), topography (DTM2006) and a seismic crust model, the latter being the recent digital global crustal model (CRUST1.0) with a resolution of 1A(0)x1A(0). The numerical results show that the estimated Moho density contrast varies from 21 to 637 kg/m(3), with a global average of 321 kg/m(3), and the estimated Moho depth varies from 6 to 86 km with a global average of 24 km. Comparing the Moho density contrasts estimated using our leastsquares method and those derived by the CRUST1.0, CRUST2.0, and PREM models shows that our estimate agrees fairly well with CRUST1.0 model and rather poor with other models. The estimated Moho depths by our least-squares method and the CRUST1.0 model agree to 4.8 km in RMS and with the GEMMA1.0 based model to 6.3 km.

  • 5.
    Abrehdary, Majid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Modelling Moho depth in ocean areas based on satellite altimetry using Vening Meinesz–Moritz’ method2016In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 51, no 2, p. 137-149Article in journal (Refereed)
    Abstract [en]

    An experiment for estimating Moho depth is carried out based on satellite altimetryand topographic information using the Vening Meinesz–Moritz gravimetric isostatichypothesis. In order to investigate the possibility and quality of satellite altimetry in Mohodetermination, the DNSC08GRA global marine gravity field model and the DTM2006 globaltopography model are used to obtain a global Moho depth model over the oceans with aresolution of 1 x 1 degree. The numerical results show that the estimated Bouguer gravity disturbancevaries from 86 to 767 mGal, with a global average of 747 mGal, and the estimatedMoho depth varies from 3 to 39 km with a global average of 19 km. Comparing the Bouguergravity disturbance estimated from satellite altimetry and that derived by the gravimetricsatellite-only model GOGRA04S shows that the two models agree to 13 mGal in root meansquare (RMS). Similarly, the estimated Moho depths from satellite altimetry andGOGRA04S agree to 0.69 km in RMS. It is also concluded that possible mean dynamictopography in the marine gravity model does not significantly affect the Moho determination.

  • 6.
    Abrehdary, Majid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The spherical terrain correction and its effect on the gravimetric-isostatic Moho determination2016In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 204, no 1, p. 262-273Article in journal (Refereed)
    Abstract [en]

    In this study, the Moho depth is estimated based on the refined spherical Bouguer gravity disturbance and DTM2006 topographic data using the Vening Meinesz-Moritz gravimetric-isostatic hypothesis. In this context, we compute the refined spherical Bouguer gravity disturbances in a set of 1 degrees x 1 degrees blocks. The spherical terrain correction, a residual correction to each Bouguer shell, is computed using rock heights and ice sheet thicknesses from the DTM2006 and Earth2014 models. The study illustrates that the defined simple Bouguer gravity disturbance corrected for the density variations of the oceans, ice sheets and sediment basins and also the non-isostatic effects needs a significant terrain correction to become the refined Bouguer gravity disturbance, and that the isostatic gravity disturbance is significantly better defined by the latter disturbance plus a compensation attraction. Our study shows that despite the fact that the lateral variation of the crustal depth is rather smooth, the terrain affects the result most significantly in many areas. The global numerical results show that the estimated Moho depths by the simple and refined spherical Bouguer gravity disturbances and the seismic CRUST1.0 model agree to 5.6 and 2.7 km in RMS, respectively. Also, the mean value differences are 1.7 and 0.2 km, respectively. Two regional numerical studies show that the RMS differences between the Moho depths estimated based on the simple and refined spherical Bouguer gravity disturbance and that using CRUST1.0 model yield fits of 4.9 and 3.2 km in South America and yield 3.2 and 3.4 km in Fennoscandia, respectively.

  • 7.
    Abrehdary, Majid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sampietro, Daniele
    Modelling Moho parameters and their uncertainties from the combination of the seismic and satellite gravity dataManuscript (preprint) (Other academic)
    Abstract [en]

    We present a method for estimating a new global Moho model (KTH15C), containing Moho depth and density contrast, from a combination of global models of gravity (GOCO05S), topography (DTM2006) and seismic information (CRUST1.0 and MDN07) to a resolution of 1°×1° based on a solution of Vening Meinesz-Moritz’ inverse problem of isostasy. Particularly, this article has its emphasis on the modelling of the observation standard errors propagated from the Vening Meinesz-Moritz and CRUST1.0 models in estimating the uncertainty of the final Moho model. The numerical results yield Moho depths ranging from 6.5 to 70.1 km, with a global average of 23.4 ± 13 km. The estimated Moho density contrasts range from 21 to 680 kg/m3, with a global average of 345.4 ± 112 kg/m3. Moreover, test computations display that in most areas estimated uncertainties in the parameters are less than 3 km and 50 kg/m3, respectively, but they reach to more significant values under Gulf of Mexico, Chile, Eeastern Mediterranean, Timor sea and parts of polar regions. Comparing the Moho depths estimated by KTH15C and those derived by KTH11C, GEMMA2012C, CRUST1.0, KTH14C, CRUST14 and GEMMA1.0 models shows that KTH15C agree fairly well with CRUST1.0 but rather poor with other models. The Moho density contrasts estimated by KTH15C and those of the KTH11C and KTH14C model agree to 120 and 80 kg/m3 in RMS. The regional numerical studies show that the RMS differences between KTH15C and Moho depths from seismic information yields fits of 2 to 4 km in South and North America, Africa, Europe, Asia, Australia and Antarctica, respectively.    

  • 8.
    Addai, Joseph
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Quantification of temporal changes in metal loads – Moss data over 20 years2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Environmental monitoring, assessment and conservation programmes worldwide have led to the development of scientific and technological methods to study the changes in our environment. As a result, a technique for monitoring atmospheric metal deposition was developed in Sweden in the 1960s. This technique is based on the principle that, carpet-forming moss obtains its nutrients from dry deposition particles in the air. The Swedish Environmental Research institute (IVL) has a database of concentrations of metals in terrestrial mosses. These were sampled during the national moss surveys (1975 – 2000). From these point data, long-term changes in the deposition loads can be studied.One aim of this project is to create continuous surfaces for these point data and to develop a technique to map the spatio-temporal changes. It also seeks to quantify the temporal changes in metal loads of the moss data for over 20 years. With the amount of data increasing from various air quality assessments and monitoring methods, it is prudent to approach the data analysis from a multidisciplinary perspective. By using statistics, geostatistic, GIS and visualization methods, the quantitative, spatial and temporal trends of the moss surveys were analysed. Multidimensional visualizations based on exploratory data analysis were applied to the data to visualize and reveal trends in the multivariate data.The project area comprised the whole Sweden with the data from 1975 to 2000, with the exception of the moss survey in 1975, which was conducted only in southern Sweden. A combination of GIS, geostatistics and high dimensional visualization techniques were applied in the data cleaning and analysis stages.The results of the project show the rate of change of metal loads over the years and the spatial distribution of the metal depositions as well. The visual approach used from the data cleaning to results presentation makes it easily comprehensible to non-scientist as well.

  • 9.
    Ahmed, Kazi Iashtiak
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    ENVISAT ASAR for Land Cover Mappingand Change Detection2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The principal objective of this research is to investigate the capability of multi-temporal,multi-incidence angle, dual polarization ENVISAT ASAR imagery for extractinglanduse/land cover information in the rural-urban fringe of the Greater Toronto Area (GTA)using different image processing techniques and classification algorithms. An attempt todetermine the temporal change of landuse is also made.The multi-temporal ASAR imagery was first orthorectified using NTDB DEM and satelliteorbital models. Different image processing techniques, such as, Adaptive Speckle Filtering,Texture measures, Principal Component Analysis (PCA) were applied to the ASAR images.Backscatter profiles were generated for selected land cove classes. K Nearest neighbor (kNN)classifier was used to extract eleven land cover classes. Artificial Neural Network (ANN) wasalso tested with some selected combinations of ASAR imagery. The classification schemewas adopted from USGS alnuse/land cover classification scheme. Average accuracy, overallaccuracy and Kappa coefficients were calculated for all classifications.The raw ASAR images gave very poor results in identifying landuse/land cover classes due tothe presence of immense speckle. Enhanced Frost (EF) filtering significantly improved theclassification accuracies. For texture measures, eleven date Mean images produced the bestresult among all single set processed data. Combined Mean and Standard Deviation,combinations of different texture measures, further improved the results. Standard deviationprovided vital auxiliary boundary information to the classification resulting in theimprovement. The best kNN was achieved with combined Mean and Standard Deviation withmulti-incidence angle, dual polarization eleven date ASAR images. ANN further improvedthe classification results of the textured images. As for comparison of classifiers, It was foundthat, with complex combinations (dual polarization, multi-incidence angle), ANN performssignificantly better than kNN. The overall accuracy was 9.6% higher than that of kNN. Theresults were more or less similar in filtered images.Post classification change detection is largely dependent on classification accuracy ofindividual images. Even though, the classification results were somewhat satisfactory, theclassified ASAR image still had a significant amount or omission and commission errors withsome classes. The classification errors contributed a significant amount of noise in changedetection. The change detection procedure, however, was able to identify the areas ofsignificant change, for example, major new roads, new low and high built up areas and golfcourses.In brief, ENVISAT ASAR data was found to have vast potential in extracting land coverinformation. Especially with its all weather capability, ASAR can be used together with highresolutionoptical images for temporal studies of landuse/land cover change due to urbansprawl.

  • 10.
    Ahnlén, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    MAP DESIGN: A development of background map visualisation in Digpro dpPower application2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    What is good map design and how should information best be visualised for a human reader? This is a general question relevant for all types of design and especially for digital maps and various Geographic Information Systems (GIS), due to the rapid development of our digital world. This general question is answered in this thesis by presenting a number of principles and tips for design of maps and specifically interactive digital visualisation systems, such as a GIS.

    Furthermore, this knowledge is applied to the application dpPower, by Digpro, which present the tools to help customers manage, visualise, design and perform calculations on their electrical networks. The visualisation and design of the network was analysed together with the usage of two common background maps, GSD-Fastighetskartan by Lantmäteriet and Primärkartan by the municipalities, whose default appearances are defined by Digpro. The aim was to answer whether there is a more suitable design of the background maps and network to better complement the usage of dpPower and if so, what is the better design?

    When designing interactive systems that will later have various end-users, a user-centred design is important. Therefore, the initial step was to collect user inputs and feedback on the current design via customer interviews. This gave a set of user criteria for good map design of dpPower specifically.

    A study of existing relevant literature and previous work was also performed where several general key principles for good design could be identified.

    Finally, a comparison between the dpPower design and other existing map products, such as e.g. Google Maps and Eniro, was made where key similarities and dissimilarities were identified and discussed.

    These user criteria and design principles could be combined, both to present an answer to the general question “What is good design?” and to present a suggestion of new map appearance in dpPower. Key considerations in the new design suggestions were e.g. to have a toned down background map with all features in the same hue family. However, for GSD-Fastighetskartan the important convention of land classes, blue = water, green = vegetation \& yellow = open land, should be kept. Colour combinations and contrast is the most important design element and since a design cannot be optimally adapted for all types of colour vision deficiencies, the suggestion is to separate the designs to specifically target user groups of different colour vision abilities. Important map information such as e.g. detailed road data should be kept while unnecessary features such as contour lines and polygon borderlines should be hidden. Text positions should also be considered.

    The results were evaluated both via a survey, distributed to users of dpPower, GIT-students and users with no previous experience of GIT or dpPower, and a seminar with employees at Digpro.

    The conclusions drawn from the evaluation was that the presented design suggestions and principles are good, but adjustments should be made. E.g. a use of yellow for low voltage cables, as suggested for Red-Green impaired, is perhaps not the best solution. The results present a good foundation for design of dpPower but more adjustments should be made based on the evaluation and then another evaluation can be performed. It would give an even better result.

  • 11.
    Alemu, Gulilat Tegane
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Assessments on the effects of mixing different types of GPS antennas and recievers.2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The accuracy and reliability of the GPS system mainly depend on the GPS receivercomponents i.e. the GPS antenna and receiver. GPS receiver components are influencedby their types and methods of calibration. Antenna calibration determines individual GPSantenna phase variations, considering specified orientation. Different approaches ofantenna calibrations provide different GPS accuracies. Therefore, in order to obtain therequired accuracy from specific campaign of GPS measurements, selection of suitableantenna types and use of the same antenna and calibration method are recommended. TheGPS antenna part of this thesis is focused on the effects of changing antenna orientationfrom originally calibrated direction (north), and then on the effects of mixing differenttypes of GPS antennas. Trimble Compact L1/L2, Zephyr Geodetic, Leica AT502, andAshtech 701945 E_M Rev E antennas and Trimble R7, Trimble 4000SSE, and Leicareceivers are used for this investigation.Orientation effects of antennas are studied by using two Trimble receivers and Ashtechantenna. Significant variations are observed on the horizontal vector components than onthe height vector components and maximum variations are observed when rover stationantenna pointing south. Form the investigation made on the effects of mixing differenttypes of antennas great variations are observed on the height vector components than onthe horizontal vector components, which range from ±2 to 4cm and variation reachedmaximum at Leica-to-Ashtech antenna combinations. They increase by ±1-2mm and ±2-3cm on the horizontal and on the vertical vector components, (respectively) whenantenna correction factors are removed from the rover station. From the investigationmade on the effects of mixing different types of GPS receivers the variations on thevertical vector components mostly lie between ±6-8mm,whereas the variation on thehorizontal vector components lie between ±2mm. The result shows an agreement withpreviously done experiment by Freymueller (1992). Moreover, maximum variations areobserved to Trimble R7-to-Trimble 4000SSE and/or Trimble R7-to-Leica receiver withLeica-to-Ashtech antenna combinations. However, effects of mixing different types ofGPS receivers are smaller when comparing with the effects of mixing different types ofGPS receivers. Therefore, this agreed with Völksen (2002).Finally, this investigation has given an insight for the need of giving particular attentionwhen mixing different types of GPS antennas and/or receivers to the same campaign,specifically, which needs greater height accuracy. The thesis also recommends that theneed and importance of further research using greater numbers and types of GPSinstruments using the same and/or different approach to arrive at quantifiable values ofthe effects on each vector components and to investigate the sources of strange results.

  • 12.
    Alizadeh Khameneh, Mohammad Amin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    On Optimisation and Design of Geodetic Networks2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Optimisation of a geodetic network is performed to provide its pre-set quality requirements. Today, this procedure is almost run with the aid of developed analytical approaches, where the human intervention in the process cycle is limited to defining the criteria. The existing complication of optimisation problem was terminated by classifying it into several stages. By performing these steps, we aim to design a network with the best datum, configuration and the observation weights, which meets the precision, reliability and cost criteria.

    In this thesis, which is a compilation of four papers in scientific journals, we investigate the optimisation problem by developing some new methods in simulated and real applications.

    On the first attempt, the impact of different constraints in using a bi-objective optimisation model is investigated in a simulated network. It is particularly prevalent among surveyors to encounter inconsistencies between the controlling constraints, such as precision, reliability and cost. To overcome this issue in optimisation, one can develop bi-objective or multi-objective models, where more criteria are considered in the object function. We found out that despite restricting the bi-objective model with precision and reliability constraints in this study, there is no significant difference in results compared to the unconstrained model. Nevertheless, the constrained models have strict controls on the precision of net points and observation reliabilities.

    The importance of optimisation techniques in optimal design of displacement monitoring networks leads to the development of a new idea, where all the observations of two epochs are considered in the optimisation procedure. Traditionally, an observation plan is designed for a displacement network and repeated for the second epoch. In the alternative method, by using the Gauss-Helmert method, the variances of all observations are estimated instead of their weights to perform the optimisation. This method delivers two observation plans for the two epochs and provides the same displacement precision as the former approach, while it totally removes more observations from the plan.

    To optimise a displacement monitoring network by considering a sensitivity criterion as a main factor in defining the capacity of a network in detecting displacements, a real case study is chosen. A GPS displacement monitoring network is established in the Lilla Edet municipality in the southwest of Sweden to investigate possible landslides. We optimised the existing monitoring network by considering all quality criteria, i.e. precision, reliability and cost to enable the network for detecting 5 mm displacement at the net points. The different optimisation models are performed on the network by assuming single baseline observations in each measurement session. A decrease of 17% in the number of observed baselines is yielded by the multi-objective model. The observation plan with fewer baselines saves cost, time and effort on the project, while it provides the demanded quality requirements.

    The Lilla Edet monitoring network is also used to investigate the idea, where we assume more precise instruments in the second of two sequential epochs. In this study, we use a single-objective model of precision, and constrained it to reliability. The precision criterion is defined such that it provides the sensitivity of the network in detecting displacements and has a better variance-covariance matrix than at the first epoch. As the observations are GPS baselines, we assumed longer observation time in the second epoch to obtain higher precision. The results show that improving the observation precision in the second epoch yields an observation plan with less number of baselines in that epoch. In other words, separate observation plans with different configurations are designed for the monitoring network, considering better observation precision for the latter epoch.

  • 13.
    Alizadeh Khameneh, Mohammad Amin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management, Stockholm, Sweden.
    Optimal Design in Geodetic GNSS-based Networks2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    An optimal design of a geodetic network helps the surveying engineers maximise the efficiency of the network. A number of pre-defined quality requirements, i.e. precision, reliability, and cost, of the network are fulfilled by performing an optimisation procedure. Today, this is almost always accomplished by implementing analytical solutions, where the human intervention in the process cycle is limited to defining the requirements. Nevertheless, a trial and error method can be beneficial to some applications. In order to analytically solve an optimisation problem, it can be classified to different orders, where an optimal datum, configuration, and optimal observation weights can be sought such that the precision, reliability and cost criteria are satisfied.

    In this thesis, which is a compilation of six peer-reviewed papers, we optimised and redesigned a number of GNSS-based monitoring networks in Sweden by developing new methodologies. In addition, optimal design and efficiency of total station establishment with RTK-GNSS is investigated in this research.

    Sensitivity of a network in detecting displacements is of importance for monitoring purposes. In the first paper, a precision criterion was defined to enable a GNSS-based monitoring network to detect 5 mm displacements at each network point. Developing an optimisation model by considering this precision criterion, reliability and cost yielded a decrease of 17% in the number of observed single baselines implying a reliable and precise network at lower cost. The second paper concerned a case, where the precision of observations could be improved in forthcoming measurements. Thus a new precision criterion was developed to consider this assumption. A significant change was seen in the optimised design of the network for subsequent measurements. As yet, the weight of single baselines was subject to optimisation, while in the third paper, the effect of mathematical correlations between GNSS baselines was considered in the optimisation. Hence, the sessions of observations, including more than two receivers, were optimised. Four out of ten sessions with three simultaneous operating receivers were eliminated in a monitoring network with designed displacement detection of 5 mm. The sixth paper was the last one dealing with optimisation of GNSS networks. The area of interest was divided into a number of three-dimensional elements and the precision of deformation parameters was used in developing a precision criterion. This criterion enabled the network to detect displacements of 3 mm at each point.

    A total station can be set up in the field by different methods, e.g. free station or setup over a known point. A real-time updated free station method uses RTK-GNSS to determine the coordinates and orientation of a total station. The efficiency of this method in height determination was investigated in the fourth paper. The research produced promising results suggesting using the method as an alternative to traditional levelling under some conditions. Moreover, an optimal location for the total station in free station establishment was studied in the fifth paper. It was numerically shown that the height component has no significant effect on the optimal localisation.

  • 14.
    Alizadeh Khameneh, Mohammad Amin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimization of Lilla Edet Land Slide GPS Monitoring Network2014Conference paper (Other academic)
  • 15.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University West, Division of Surveying Engineering.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimisation of Lilla Edet Landslide GPS Monitoring Network2015In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 5, no 1, p. 57-66Article in journal (Refereed)
    Abstract [en]

    Since the year 2000, some periodic investigations have been performed in the Lilla Edet region to monitor and possibly determine the landslide of the area with the GPS measurements. The responsible consultant has conducted this project by setting up some stable stations for GPS receivers in the risky areas of Lilla Edet and measured the independent baselines amongst the stations according to their observation plan. Here, we optimise the existing surveying network and determine the optimal configuration of the observation plan based on different criteria. We aim to optimise the current network to become sensitive to detect 5 mm possible displacements in each net point. The network quality criteria of precision, reliability and cost are used as object functions to perform single-, bi- and multi-objective optimisation models. It has been shown in the results that the single-objective model of reliability, which is constrained to the precision, provides much higher precision than the defined criterion by preserving almost all of the observations. However, in this study, the multi-objective model can fulfil all the mentioned quality criteria of the network by 17% less measurements than the original observation plan, meaning 17% of saving time, cost and effort in the project.

  • 16.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Department of Engineering Science, University West, Trollhättan, Sweden.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The Effect of Instrumental Precision on Optimisation of Displacement Monitoring Networks2016In: Acta Geodaetica et Geophysica, ISSN 2213-5820, Vol. 51, no 4, p. 761-772Article in journal (Refereed)
    Abstract [en]

    In order to detect the geo-hazards, different deformation monitoring networks are usually established. It is of importance to design an optimal monitoring network to fulfil the requested precision and reliability of the network. Generally, the same observation plan is considered during different time intervals (epochs of observation). Here, we investigate the case that instrumental improvements in sense of precision are used in two successive epochs. As a case study, we perform the optimisation procedure on a GPS monitoring network around the Lilla Edet village in the southwest of Sweden. The network was designed for studying possible displacements caused by landslides. The numerical results show that the optimisation procedure yields an observation plan with significantly fewer baselines in the latter epoch, which leads to saving time and cost in the project. The precision improvement in the second epoch is tested in several steps for the Lilla Edet network. For instance, assuming two times better observation precision in the second epoch decreases the number of baselines from 215 in the first epoch to 143 in the second one.

  • 17.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University West, Department of Engineering Science.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The Effect of Instrumental Precision on Optimisation of Epoch-Wise Displacement Networks2015Conference paper (Other academic)
  • 18.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Horemuž, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Vium Andersson, Johan
    WSP Civils, Department of Geographic Information and Asset Management.
    Optimal Vertical Placement of Total Station2018In: Journal of Surveying Engineering, ISSN 0733-9453, E-ISSN 1943-5428Article in journal (Refereed)
    Abstract [en]

    When using the free station method, a Total Station (TS) is established by performing distance and angle observations toward a number of Control Points (CPs). The quality of the establishment is crucial for the quality of subsequent measurements. The optimal horizontal location of the TS has been investigated in previous studies. Even the vertical precision is important in many applications, especially with significant height variations. Therefore in this paper, we focus on the optimality of vertical location of the TS. As an optimality criterion, the sum of TS coordinates and orientation variances is used. To investigate the optimization problem, an analytical as well as a trial and error method is developed. Both methods showed that the height component has no significant influence on the optimal vertical placement of the TS. Inspection of results from the trial and error method, where the CPs are moved in different height layers, indicates differences in the height uncertainty of the establishment in micrometer range, which is negligible for most engineering applications.

  • 19.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Horemuž, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Andersson, Johan Vium
    WSP Civils, Department of Geographic Information and Asset Management.
    Investigation of the RUFRIS Method with GNSS and Total Station for Leveling2017Conference paper (Refereed)
    Abstract [en]

    The establishment of leveling benchmarks for performing geodetic measurements, for instance in construction works, is usually costly and laborious due to a mass of field works in transferring the height from nearby known benchmarks. In this study, a real-time updated free station (RUFRIS) method is investigated to be used as an alternative approach for the traditional leveling. The coordinates of a RUFRIS station are determined by establishing a total station on the point, and performing a free-station by observing some points with both Real-Time Kinematic (RTK) GNSS and total station distance and direction observations. The study is conducted based on data from the East Link project in Sweden, where a 150 km long high-speed railway is to be constructed. The results show a standard deviation of 7 mm between the RUFRIS and leveling heights in this project and imply the feasibility of replacing the traditional leveling methods with RUFRIS in projects with low accessibility to benchmarks.

  • 20.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimisation of GNSS Networks - Considering Baseline Correlations2017In: Survey review - Directorate of Overseas Surveys, ISSN 0039-6265, E-ISSN 1752-2706, p. 1-8Article in journal (Refereed)
    Abstract [en]

    By considering GNSS observations one can perform optimisation according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead assume single-baseline adjusted data in the optimisation procedure. However, in each session of observation usually more than two receivers are simultaneously taking data from a number of common GNSS satellites, implying that the single or double difference observations are correlated. Our study designs an optimal observation plan for a GPS network in Skåne in southern Sweden, with the aim of determining possible displacements. Assuming three receivers in each session of observations leads to correlation between the GPS baselines, and consequently a fully populated weight matrix for each session of observation. A bi-objective optimisation model of precision and reliability is chosen to optimise the variance factor of each session, and eventually, design an observation plan. It is shown in this study that observing 6 out of 10 possible sessions are sufficient to enable the network to detect a 5 mm displacement at each station. Assuming that the double difference phase observations are uncorrelated changes the observation plan by retaining 2 more sessions. However, defining the weight matrix based on the double difference observations requires the correlations to be taken into account, and neglecting them leads to incorrect results.

  • 21.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimization of GNSS Deformation Monitoring Networks by Considering Baseline Correlations2016In: FIG Working Week 2016 Proceedings, 2016Conference paper (Other academic)
    Abstract [en]

    In the study of deformations of man-made constructions or in geodynamics one usually needs to carefully monitor fixed objects attached to the deformable body. The purpose is to use precise observations to build up an accurate, reliable and possibly low-cost network around the objects to study their motion in short- or long-time intervals and to estimate the possible displacements or deformations among those objects. Frequently, such studies are performed to prevent unwanted disasters (e.g. due to earthquakes and landslides as well as the progressive or abrupt destruction of large-scale structures). This study is concerned with designing an optimal GNSS network to monitor possible deformations of a geodetic network.

    By considering GNSS observations one can perform the optimization according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead use single-baseline adjusted data in the optimisation procedure. However, in each session of observation usually more than two receivers are simultaneously taking data from a number of common GNSS satellites. This procedure inevitably leads to between-baseline correlations. Our study designs an optimal observation plan for a GNSS monitoring network with the aim of determining possible displacements and deformations. The developed methodology will be tested on a simulated network with five points, where three receivers simultaneously take data from four satellites.

  • 22.
    Andrei, Octavian
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    3D affine coordinate transformations2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the three-dimensional (3D) coordinate transformation from a globalgeocentric coordinate system to a national terrestrial coordinate system. Numerical studies arecarried out using the Swedish geodetic data SWEREF 93 and RT90/RH70. Based on theHelmert transformation model with 7-parameters, two new models have been studied: firstly ageneral 3D affine transformation model has been developed using 9-parameters (threetranslations, three rotations and three scale factors) and secondly the model with 8-parameters(three translations, three rotations and two scale factors) has been derived. To estimate the 3Dtransformation parameters from given coordinates in the two systems, the linearizedobservation equations were derived. Numerical tests were carried out using a local (North,East, Up) topocentric coordinate system derived from the given global geocentric system. Thetransformation parameters and the residuals of the coordinates of the common points werecomputed. The investigation shows the horizontal scale factor is significantly different by thevertical scale factor. The residuals of the control points were expressed in a separate (North,East, Up) coordinate system for each control point. Some investigations on the weightingprocess between horizontal and vertical components were also carried out, and an optimalweighting model was derived in order to reduce the residuals in horizontal componentswithout changing the coordinates.

  • 23.
    Bagherbandi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University of Gävle, Sweden.
    Deformation monitoring using different least squares adjustment methods: A simulated study2016In: KSCE Journal of Civil Engineering, ISSN 1226-7988, E-ISSN 1976-3808, Vol. 20, no 2, p. 855-862Article in journal (Refereed)
    Abstract [en]

    This study aims to investigate the ability of different least squares adjustment techniques for detecting deformation. A simulated geodetic netwo rk is used for this purpose. The observations are collected using the Total Station instrument in three epochs and different least squares adjustment methods are used to analyze the simulated network. The applied methods are adjustment-byelement, using variance-covariance components and Tikhonov regularization. For numerical computation, we utilized exist geodetic network around the simulated network and the deformation (changes in the simulated network) imposes to the object using a simulator in each epoch. The obtained results demonstrate that more accurate outcome for detection of small deformation is possible by estimating variance-covariance components. The difference of the estimated and the simulated deformations in the best scenario, i.e., applying variance-covariance components, is 0.2 and 0.1 mm in x and y directions. In comparison with adjustment by element and Tikhonov regularization methods the differences are 1.1 and 0.1 in x direction and 1.4 and 1.1 mm in y direction, respectively. In addition, it is also possible to model the deformation and therefore it can be seen that how the calculated displacement will affect the result of deformation modelling. It has been demonstrated that determining reasonable variance-covariance components is very important to estimate realistic deformation model and monitoring the geodetic networks.

  • 24.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bai, Y.
    Sjöberg, L. E.
    Tenzer, R.
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Miranda, S.
    Alcacer Sanchez, J. M.
    Effect of the lithospheric thermal state on the Moho interface: A case study in South America2017In: Journal of South American Earth Sciences, ISSN 0895-9811, E-ISSN 1873-0647, Vol. 76, p. 198-207Article in journal (Refereed)
    Abstract [en]

    Gravimetric methods applied for Moho recovery in areas with sparse and irregular distribution of seismic data often assume only a constant crustal density. Results of latest studies, however, indicate that corrections for crustal density heterogeneities could improve the gravimetric result, especially in regions with a complex geologic/tectonic structure. Moreover, the isostatic mass balance reflects also the density structure within the lithosphere. The gravimetric methods should therefore incorporate an additional correction for the lithospheric mantle as well as deeper mantle density heterogeneities. Following this principle, we solve the Vening Meinesz-Moritz (VMM) inverse problem of isostasy constrained by seismic data to determine the Moho depth of the South American tectonic plate including surrounding oceans, while taking into consideration the crustal and mantle density heterogeneities. Our numerical result confirms that contribution of sediments significantly modifies the estimation of the Moho geometry especially along the continental margins with large sediment deposits. To account for the mantle density heterogeneities we develop and apply a method in order to correct the Moho geometry for the contribution of the lithospheric thermal state (i.e., the lithospheric thermal-pressure correction). In addition, the misfit between the isostatic and seismic Moho models, attributed mainly to deep mantle density heterogeneities and other geophysical phenomena, is corrected for by applying the non-isostatic correction. The results reveal that the application of the lithospheric thermal-pressure correction improves the RMS fit of the VMM gravimetric Moho solution to the CRUST1.0 (improves ∼ 1.9 km) and GEMMA (∼1.1 km) models and the point-wise seismic data (∼0.7 km) in South America.

  • 25.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Bai, Yongliang
    Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences No.7 Nanhai Rd, Qingdao 266071, China.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Tenzer, Robert
    School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan, China..
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Miranda, Silvia
    Departamento de Geofísica y Astronomía, FCEFN. Universidad Nacional de San Juan, Meglioli 1160 Sur, 5400. Rivadavia, San Juan, Argentina.
    Sanchez, Juan
    Departamento de Geofísica y Astronomía, FCEFN. Universidad Nacional de San Juan, Meglioli 1160 Sur, 5400. Rivadavia, San Juan, Argentina..
    Effect of the lithospheric thermal state on the Moho geometryManuscript (preprint) (Other academic)
    Abstract [en]

    Gravimetric methods applied for a Moho recovery in areas with sparse and irregular distribution of seismic data often assume only a constant crustal density. Results of the latest studies, however, indicate that corrections for the crustal density heterogeneities could improve the gravimetric result especially in regions with a complex geologic/tectonic structure. Moreover, the isostatic mass balance reflects also the density structure within the mantle. The gravimetric methods should therefore incorporate an additional correction for the sub-crustal density heterogeneities. Following this principle, we solve the Vening Meinesz-Moritz (VMM) inverse problem of isostasy constrained on seismic data to determine the Moho depth of the South American tectonic plate including surrounding oceans, while taking into consideration the crustal and mantle density heterogeneities. Our numerical result confirms that the contribution of sediments significantly modifies the Moho geometry especially along the continental margins with large sediment deposits. To account for the mantle density heterogeneities we develop and apply a method of correcting the Moho geometry for the contribution of the lithospheric thermal state (i.e., the lithospheric thermal-pressure correction). In addition, the misfit between the isostatic and seismic Moho models, attributed mainly to deep mantle density heterogeneities and other geophysical phenomena, is corrected for by applying the non-isostatic correction. The results reveal that the application of the lithospheric thermal-pressure correction improves the RMS fit of the VMM gravimetric Moho solution to the CRUST1.0 seismic model and the point-wise seismic data in South America about 40% and 7% respectively.  

  • 26.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University of Gävle, Sweden .
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Tenzer, Robert
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    A new Fennoscandian crustal thickness model based on CRUST1. 0 and a gravimetric–isostatic approach2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 145, p. 132-145Article, review/survey (Refereed)
    Abstract [en]

    In this paper a new gravimetric–isostatic crustal thickness model (VMM14_FEN) is estimated for Fennoscandia. The main motivation is to investigate the relations between geological and geophysical properties, the Moho depth and crust–mantle density contrast at the crust–mantle discontinuity. For this purpose the Bouguer gravity disturbance data is corrected in two main ways namely for the gravitational contributions of mass density variation due to the different layers of the Earth's crust such as ice and sediments, as well as for the gravitational contribution from deeper masses below the crust. This second correction (for non-isostatic effects) is necessary because in general the crust is not in complete isostatic equilibrium and the observed gravity data are not only generated by the topographic/isostatic masses but also from those in the deep Earth interior. The correction for non-isostatic effects is mainly attributed to unmodeled mantle and core boundary density heterogeneities. These corrections are determined using the recent seismic crustal thickness model CRUST1.0. We compare our modeling results with previous studies in the area and test the fitness. The comparison with the external Moho model EuCRUST-07 shows a 3.3 km RMS agreement for the Moho depth in Fennoscandia. We also illustrate how the above corrections improve the Moho depth estimation. Finally, the signatures of geological structures and isostatic equilibrium are studied using VMM14_FEN, showing how main geological unit structures attribute in isostatic balance by affecting the Moho geometry. The main geological features are also discussed in the context of the complete and incomplete isostatic equilibrium.

  • 27.
    Bengtsson, Jonas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Grönkvist, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Performing Geographic Information System Analyses on Building Information Management Models2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the usage of both BIM (Building Information Modelling) and 3D-GIS (Three-Dimensional Geographic Information Systems) has increased within the field of urban development and construction, so has the interest in connecting these two tools.  One possibility of integration is the potential of visualising BIM models together with other spatial data in 3D. Another is to be able to perform spatial 3D analyses on the models. Both of these can be achieved through use of GIS software.

    This study explores how integration of BIM and GIS could look. The goal was to perform typical GIS analyses in 3D on BIM models. Previous research points towards some success within the field through use of the indicated standard format for each tool – IFC (Industry Foundation Classes) for BIM and CityGML (City Geographic Markup Language) for GIS. Transformation between the formats took place through use of the BIM software Revit, the transformation tool FME and the GIS software ArcGIS. A couple of reviewed applications of GIS analyses were chosen for testing on the converted models – indoor network analysis, visibility analysis and spatial analysis for 3D buildings.

    The input data in the study was several BIM models, both models created for real-life usage and others that only function as sample data within the different software. From the results of the practical work it can be concluded that a simple, automated and full-scale integration does not seem to be within reach quite yet. Most transformations between IFC and CityGML failed to some extent, especially the more detailed and complex ones. In some test cases, the file could not be imported into ArcGIS and in others geometries were missing or existing even though they should not. There were also examples where geometries had been moved during the process. As a consequence of these problems, most analyses failed or did not give meaningful results. A few of the original analyses did give positive results. Combining (flawed) CityGML models with other spatial data for visualisation purposes worked rather well. Both the shadow volume and sightline analyses did also get reasonable results which indicates that there might be a future for those applications.

    The obstacles for a full-scale integration identified during the work were divided into four different categories. The first is BIM usage and routines where created models need to be of high quality if the final results are to be correct. The second are problems concerning the level of detail, especially the lack of common definitions for the amount of details and information. The third category concerns the connection between local and global coordinate systems where a solution in form of updates to IFC might already be in place. The fourth, and largest, category contains those surrounding the different formats and software used. Here, focus should lie on the transformation between IFC and CityGML.

    There are plenty of possible, future, work concerning these different problems. There is also potential in developing own tools for integration or performing different analyses than those chosen for this thesis.

  • 28.
    Bengtsson, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Förändringsanalys i ortofoton2007Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This Master of Science thesis discusses the subject change detection and aims to studythe possibilities to perform change detection in orthophotos of the city of Stockholm inorder to discover new buildings and roads. The Stockholm City Planning Administrationis seeking a possibility to do so in order to eciently update the map database, sinceapproved construction work often is nished without being reported to the municipalityfor nal registration in the database.Orthophotos of Stockholm from the years 2002 and 2005, resampled to 1 meter resolution,were used as data for the project. Dierent existing change detection methodsin the softwares Geomatica, Idrisi and SOCET SET were tested on the data, but theresults and ease of use were not considered to meet the needs of the City Planning Administration,hence the development of a new and adapted application for change detectionbecame the focus of interest of the thesis.The application was developed in Java and except for the image dierencing operation,which is carried out as in the tested softwares, the new application was also givenfunctions e.g. for calibrating images and automatically and manually reducing noise anduninteresting changes in the dierence image. Unlike the tested softwares, the new applicationperforms image dierencing in all bands of the images, which generates a colorcomposite dierence image, instead of a grayscale image.The fact that the orthophotos are not true orthophotos complicates the change detectionprocess. The radial displacement makes buildings lean in dierent directions in the dierentorthophotos, which generates many unwanted changes. The orthophotos also dierbecause of shadow and vegetation variations, and the problem with shadow variationsgrows with building heights, which states that in these orthophotos it is not recommendedto perform change detection in areas with tall buildings. Change detection ispreferably performed in areas with low buildings in those areas change detection oftengenerates an acceptable result, especially with the aid from the adapted application.

  • 29.
    Bergkvist, Joel
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimal Design of Network for Control of Total Station Instruments2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis uses the Minimum Norm Quadratic Unbiased Estimation (MINQUE) to estimatestandard deviation of observations of a total station. Different setups are created byaltering the number of stations and targets and their relative position in the network tostudy the effect that different setups have to the estimation and define what are importantto minimize the effect of the setup to the estimation.A lot of research has been done around methods for estimation of variance and covariancecomponents, since it is useful in many fields. Various approaches exists to solve theproblem of variance components estimation. Geodesy is a special case, were their often isa apriori knowledge of how well an instrument is able to record measurements. There isan ISO-standard for testing and verification of geodetic instrument but also an alternativeapproach the KTH-Total Station Check.For the estimation three main types of setups were defined and used in the simulation.These main types were then altered to see how different changes to the setup effect theoverall estimation. The alterations were changes in distance between station and targets,changes in vertical distance between stations and targets and the amount of observationscarried out by adding more stations and targets to the setups.The result of the simulations shows that the tested changes in the setups do effectthe estimation. It was not possible to determine by how much for each change, becausea change in vertical displacement also meant a change in angles and distance betweenthe station and the target. Increasing the amount of stations and targets or one of themshows that standard deviation of the estimation becomes smaller. The effect can be seenindependent of which type of setup that is used. The most important factor to how goodthe estimation will be is the amount of observations.

  • 30.
    Bergsjö, Joline
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Photogrammetric point cloud generation and surface interpolation for change detection2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years the science revolving image matching algorithms has gotten an upswing mostly due to its benefits in computer vision. This has led to new opportunities for photogrammetric methods to compete with LiDAR data when it comes to 3D-point clouds and generating surface models. In Sweden a project to create a high resolution national height model started in 2009 and today almost the entirety of Sweden has been scanned with LiDAR sensors. The objective for this project is to achieve a height model with high spatial resolution and high accuracy in height. As for today no update of this model is planned in the project so it’s up to each municipality or company who needs a recent height model to update themselves. This thesis aims to investigate the benefits and shortcomings of using photogrammetric measures for generating and updating surface models. Two image matching software are used, ERDAS photogrammetry and Spacemetric Keystone, to generate a 3D point cloud of a rural area in Botkyrka municipality. The point clouds are interpolated into surface models using different interpolation percentiles and different resolutions.

    The photogrammetric point clouds are evaluated on how well they fit a reference point cloud, the surfaces are evaluated on how they are affected by the different interpolation percentiles and image resolutions. An analysis to see if the accuracy improves when the point cloud is interpolated into a surface. The result shows that photogrammetric point clouds follows the profile of the ground well but contains a lot of noise in the forest covered areas. A lower image resolution improves the accuracy for the forest feature in the surfaces. The results also show that noise-reduction is essential to generate a surface with decent accuracy. Furthermore, the results identify problem areas in dry deciduous forest where the photogrammetric method fails to capture the forest.

  • 31.
    Bärlund, Johnny
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Numerical Investigation on Spherical Harmonic Synthesis and Analysis2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis work the accuracy of the spherical harmonic synthesis and analysis are investigated, by simulated numerical studies.The main idea is to investigate the loss of accuracy, in the geopotential coeffcients, by the following testing method. We start with a synthesis calculation, using the coefficients(EGM2008), to calculate geoid heights on a regular grid. Those geoid heights are then used in an analysis calculation to obtain a new set of coeffcients, which are in turn used to derive a new set of geoid heights. The difference between those two sets of geoid heights will be analyzed to assess the accuracy of the synthesis and analysis calculations.The tests will be conducted with both point-values and area-means in the blocks in the grid. The area-means are constructed in some different ways and will also be compared to the mean value from 10000 point values as separate tests. Numerical results from this investigation show there are signifi…cant systematic errors in the geoid heights computed by spherical harmonic synthesis and analysis, sometimes reaching as high as several meters. Those big errors are most common at the polar regions and at the mid-latitude regions.

  • 32.
    Bånkestad, Qarin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Faktisk hantering för att kunna lagra, återfå och visualisera tredimensionell information2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today the municipality of Eskilstuna stores two-dimensional data on a SQL-server with anArcSDE application running on it, but they also want to store three-dimensional data. There isno standard yet for how to store three-dimensional data, but techniques to collect andvisualize three-dimensional geographical data are rapidly developing.In this thesis, simple ways to handle three-dimensional data have been investigated. The ideais that three dimensional data should be stored in the existing ArcSDE-database. It must bepossible to check out, refine and deliver the data back to the database again. Five softwareswere chosen for the tests. The requirement for the software is that it should be possible forrefined models to be reimported into the database, and that in the process, the models canretain shape and other information. It is important to study how the existing attributes of themodel can be maintained throughout the conversions. One of the tasks in this thesis was alsoto investigate which software is the best to use to refine the models.In the tests, three different models have been used. Two of them were created in softwareswhich were already in use within the organisation - AutoCad and ArcScene. The third modelwas obtained from Topeye, a company which delivers models created from laser scanneddata. The three models have then been imported and exported between the database and thedifferent softwares. The results have been evaluated to find the best method for themunicipality of Eskilstuna, to handle three-dimensional data.The results indicate that the best way for Eskilstuna to handle three-dimensional models is anenvironment from ESRI, ArcScene. From ArcScene, models in various formats can beopened. For example, models created from laser data which are delivered in some CADformatcan easily be imported to the database. Without much trouble a model can be retrieved,used in any project and then put back in the database.

  • 33.
    Danila, Uliana
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Corrective Surfacefor GPS-levelling in Moldova2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main objective of this thesis is the construction of a corrective surface in theMoldova area for further conversion of the geodetic heights into normal heights. For thispurpose a detailed analysis of the optimal combination of heterogeneous height data ispresented, with particular emphasis on (i) modeling systematic errors and datuminconsistencies, (ii) separation of random errors and estimation of variance componentsfor each height type, and (iii) practical considerations for modernizing vertical controlsystems. Although the theoretical relationship between geodetic, normal heights andheight anomalies is simple in nature, its practical implementation has proven to be quitechallenging due to numerous factors that cause discrepancies among the combined heightdata. In addition, variance component estimation is applied to the common adjustment ofthe heterogeneous heights. This leads to the connection between the proper modelling ofsystematic errors and datum inconsistencies with the estimated variance components.Ultimately, one of the main motivations for this work is the need to introduce moderntools and techniques, such as GPS/levelling, in establishing a vertical control. Therefore,part of this thesis is aimed at bringing to the forefront some of the key issues that affectthe achievable accuracy level of GPS/levelling. Overall, the analysis of the optimalcombination of the heterogeneous height data conducted herein provides valuable insightto be used for a variety of height related applications.

  • 34.
    Danila, Uliana
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    A gravimetric quasigeoid model over Moldova2013Conference paper (Refereed)
  • 35.
    Daras, IIias
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Determination of a gravimetric geoid model of Greece using the method of KTH2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main purpose of this study is to compute a gravimetric geoid model of Greeceusing the least squares modification method developed at KTH. In regional gravimetricgeoid determination, the modified Stokes’s formula that combines local terrestrial datawith a global geopotential model is often used nowadays.In this study, the optimum modification of Stokes’s formula, introduced by ProfessorSjöberg, is employed so that the expected mean square error (MSE) of all possiblesolutions of the general geoid model is minimized. According to this stochasticmethod, the Stokes’s formula is being used with the original surface gravity anomalywhich combined with a GGM yields an approximate geoid height. The corrected geoidheight is then obtained by adding the topographic, downward continuation,atmospheric and ellipsoidal corrections to the approximate geoid height.The dataset used for the computations, consisted of terrestrial gravimetricmeasurements, a DEM model and GPS/Levelling data for the Greek region. Threeglobal geopotential models (EGM96, EIGEN-GRACE02S, EIGEN-GL04C) weretested for choosing the best GGM to be combined into the final solution. Regarding theevaluation and refinement of the terrestrial gravity measurements, the cross-validationtechnique has been used for detection of outliers.The new Greek gravimetric geoid model was evaluated with 18 GPS/Levelling pointsof the Greek geodetic network. The absolute agreement between the gravimetric andthe GPS/Levelling geoid height was estimated at 27 cm while the relative agreement at0.9 ppm. In a case of study the absolute accuracy of the model was estimated at 14 cm.The geoid model computed in this study was also compared with some previous Greekgeoid models, yielding better external accuracy than them.

  • 36.
    Dastgir, Naeim
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Processing SAR data using RangeDoppler and Chirp Scaling Algorithms2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Applications of self-illuminating remote sensing systems, and among those, Radar Imagery is growingrapidly. Unique properties of Synthetic Aperture Radar (SAR) system makes it one of the most popularand applicable methods of self illuminating remote sensing techniques for ground deformationmonitoring, seismic studies, and many photogrammetry applications.There are several methods and algorithms for processing SAR data, each are convenient for differentpurposes. Two more common and reliable algorithms are developed in this thesis: a Range DopplerAlgorithm and a Chirp Scaling Algorithm.Available software packages and toolboxes for processing SAR data such as DORIS, ROI-PAC, RAT andPULSAR have their advantage and disadvantages. Most of these packages run on Linux platform, aredifficult to use, and require quite a few pre-processing data preparations. Besides there is no general SARprocessing application that can handle all data types or suitable for all purposes. There are also softwarepackages (such as ROI-PAC) with restrictions for people from certain countries.The objective of this thesis is to process SAR data using two more common algorithms, run a comparisonbetween results of these two algorithms and to process InSAR pair images to form an Interferogram andto create a DEM. A Matlab based program is developed for this purpose with graphical user interface anda few visualization enhancement features, which facilitates processing data and producing desired output.Then, I investigate the effect of different frequency domains in the resulting image.The program I created in my thesis, has several advantages: it is open-source and very easy to modify.The program is coded in MATLAB, therefore it does not need a vast programming knowledge to be ableto customize it. You can run it on any platform that can run MATLAB 7+.At the end of this thesis, I conclude that A Range Doppler Algorithm with secondary range compressionperformed in 2D-frequency domain has a result as good as a Chirp Scaling Algorithm and has lesscomputational complexity and consumes less time. No general SAR processing algorithm could beintroduced. Most of the times algorithms need to be adjusted for particular datasets, or particularapplications. Besides, the most complicated algorithm is not always the best algorithm. For example, for apoint target detection purpose, two filtering steps in range and azimuth direction provides accurateenough result.

  • 37.
    De Lama Blasco, Violeta
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Precision Analysis of Photogrammetric Data Collection Using UAV2017Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
  • 38.
    Edres, Walyeldeen Hassan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Crustal motion at the permanent GPS station SVEA, Antractica2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the last two decades, the Global Positioning System (GPS) has played a special

    role in Antarctica in the study of crustal motion. The permanent GPS station SVEA

    was installed in Antarctica by the division of geodesy at KTH. In November 14, 2004

    the station became operational and provides continuous GPS data.

    The objective of this study is to estimate the crustal motion at SVEA. The GPS data of

    the first five days of January, years 2005, 2006, 2007 and 2008 of station SVEA and six

    IGS reference stations have been processed using the Bernese GPS Software 0.5.

    Two methods (regression analysis and the Bernese software) were used to estimate

    the velocity at SVEA. In addition, horizontal velocities have been calculated from the

    plate motion calculator. A student’s t‐test has been used to judge whether the

    estimated motions are significant or not at risk level 5%.

    The estimated velocity components (in mm/year) are 8.0±1.9 North, 1.0 ± 0.5 East

    and 0.1 ± 0.9 Up in linear regression analysis and 8.4 ±1.9 North, 1.1 ± 0.5 East and

    0.2 ± 0.9 Up in the Bernese GPS Software. From the statistical test, the estimated

    velocity in the North component is significant in the Bernese GPS Software at risk

    level 5%. For the rest of the components, the estimated velocities are not significant

    for any method. The estimated horizontal velocities are mostly consistent with plate

    motion models. In order to estimate reliable and accurate crustal motion in the Up

    component, the time span should be longer than four years.

  • 39.
    Ekblad, Jacob
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Lips, Jacob
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Development of a Workflow for Automatic Classification and Digitization of Road Objects Gathered with Mobile Mapping2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mobile Mapping Systems gathers a lot of spatial data that can be used for inventory and analyses regarding road safety. The main purpose of this thesis is to propose a workflow for automatic classification and digitisation of objects in a point cloud gathered by a Mobile Mapping System.

     

    The current method used for processing point clouds is performed manually which is cost-inefficient and time consuming due to the vast amount of data the point cloud contains.

     

    Before defining the workflow, different software were reviewed for finding which ones to use for the classification. The software review showed that a combination of using Terrasolid and FME is suitable for performing the steps suggested in the classification and digitisation method.

     

    The proposed workflow for performing automatic classification and digitisation is based on six different steps: Identify characteristics of the objects of interest, Filter the point cloud, Noise reduction, Identify objects, Digitise and Control. This method has been carried out on two examples, road signs and painted road lines. Attributes that have been used for classifying the objects involves intensity, colour value and spatial relations.

    The results showed that for digitising road signs, the method found 15 out of 16 signs (94%). For digitising the painted road lines, the results produced by the automatic function had an average misalignment of 3.8 centimetres in comparison to the initial point cloud.

    The thesis demonstrates that the carried out functions are less time demanding for the user, compared to the manual method carried out today.

     

  • 40.
    Elhadi, Hussain Mohammed Ahmed
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    GIS, A tool for pavement management2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A pavement management system (PMS) should tackle all aspects of the pavement management

    process from planning and programming through project development and implementation

    (Shahin 2005). Geographic information systems (GIS) can be used to expand and enhance each

    of these PMS components. A GIS can be designed as a platform on which the PMS is built and

    operated. Such a system is designated a PMS/GIS. Few years back, the Directorate of Municipal

    Affairs (DMA) - Abu Dhabi Municipality -Roads Section took their first serious steps towards

    developing a Pavement Management System (PMS). A number of projects were initiated,

    covering Abu Dhabi Island and the Mainland, to assist in migrating from the existing

    Management Information System (MIS) to the anticipated newly developed PMS.

    A major component in most of the projects as well as this project “Maintenance,

    Rehabilitation and Additional Works for Roads and Bridges in Abu Dhabi Island” is to

    evaluate the condition of existing roads’ pavement by carrying out certain tests, which will

    indicate and suggest the further course of action for determining the strategies for the

    improvement of the roads pavement quality. In this project two types of tests were carried out,

    the Roughness Testing for the determination of the International Roughness Index (IRI) and the

    Non-destructive deflection testing particularly Falling Weight Deflection method (FWD) in

    order to determine the riding quality and to assess the structural integrity of the existing roads

    pavement respectively.

    The principal objective of this thesis is to reveal the role of the GIS technology in the

    enhancement of PMS components such as the output results from the two performed tests, and

    make it more interpretable through dynamic color coding and more sophisticated visualization

    techniques than the conventional tabular data format. Another objective was to show the

    importance of using GIS as a platform for PMSs, though it is still a few steps ahead to achieve

    this goal and requires team work involving other specializations, but ultimately it would be done

    within the course of the running projects.

    The output result from the roughness survey was GPS test locations, the processed IRI values for

    left and right wheel paths and the video streaming data. IRI values were used as an attribute data

    for the constructed, segmented lane lines in ArcGIS 9.2. Triggered roughness values were

    identified to classify IRI values into five classes reflecting the status of the pavement surface.

    The lane lines were symbolized and color-coded using these five classes. A standalone

    application known as “ROMDAS Data view” was developed based on a database comprising

    road location references (Change points), video data and the IRI values. An ArcGIS Extension,

    known as VideoDRS, was also used to enabling Indexing and playback of the video in reference

    to the GPS locations. Attribute data integration between IRI & FWD data was performed for

    each test location every 100m along the survey route.

    As a result, roughness data can be viewed through many techniques, VideoDRS and the

    ROMDAS Data view. GIS-based maps were produced for the whole Main Roads network for

    Abu Dhabi Island in reference to the condition data surveyed i.e. IRI Network & FWD Overlay

    Network.

  • 41.
    Elhassan, Elbashir Mohamed Elbashir
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The Effect of GPS Signal Quality on the Ambiguity Resolution Using the KTH method2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the last decade the integer phase ambiguity resolution has become one of

    the most important elements in the GPS field because of its impact on the

    accuracy. Several scientific researches have been carried out for resolving the

    integer ambiguity. One example of such kind of researches is the Quick GPS

    ambiguity resolution for a short baseline (KTH method). The study focus on

    investigation of the impact of the selected elements: the GPS signal, the

    observations elevation angles and the GPS satellites azimuth on the KTH

    method performance for resolving the integer phase ambiguity.

    The investigation has covered carrier phase measurements for three baselines

    with length less than one km for each and “GeoGenius” software package as

    the quality control for the fixed ambiguities of the KTH method results. The

    KTH method achieved more than 84 percent of success in the level of signal

    strength 8; about 90 percent for elevation angel between (55 􀝐􀝋 65)° and

    approximately 94 percent for GPS satellite azimuth in range of (130 􀝐􀝋 150)°.

    The overall results showed a clear correlation of about 0.9 for most of the cases

    between KTH method and the selected components. In such a case it leads to

    a high performance of the method under healthy reliable observations

    conditions, and the method has the capability to yield outcomes expected to be

    within a specific accuracy by knowing the level of group elements (signal

    strength, elevation angle and satellite azimuth) that have been used.

  • 42.
    Ergun, Firat
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Schwartz, Trevor
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    NCC GNSS RTK Network Accuracy Analysis2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this report is to provide a detailed assessment and investigation into the performance of the Real-Time Kinematic (RTK) network Nordic Construction Company (NCC) established, as part of its aim to better leverage technology within its business, to ensure the high quality and efficiency its clients have come to expect of NCC. Within the course of this investigation, extended RTK and raw data survey sessions were undertaken at each of four baselines significant to NCC (5, 15, 25, and 35 kilometers) from three of NCC’s five RTK base stations. Subsequent analysis resulted in hard documentation of the network performances and of the fidelity of the implementation itself. The research also resulted in deliverables consisting of statistics, computations, as well as utilities that will aid in decision making and allow users to better integrate and utilize the RTK network confidently within projects.

    It was found that NCC’s RTK performed essentially as expected in each circumstance and well within theory and empirical experience in terms of expected accuracies and best practices. This was concluded by comparison to accessible works by the U.S. Army Corps of Engineers and the NAVSTAR (GPS) development team. Of which are aggregated within document EM-110-1-1003 (NAVSTAR Global Positioning System Surveying) published by the U.S. Army Corps of Engineers. It is important to outline that this manual’s extensive use as a primary work throughout this report is due to authors’ trust in the publishing sources as well as the documents robust combination and illustration of theoretical and empirical content. The manual states that performance in the range of 1-3 centimeters in the horizontal and 3-10 centimeters in the vertical should be expected under the circumstances tested herein and to a majority were achieved.

    Some unique observations and patterns were identified as a result of discussion with NCC and analysis of the data. Patterns in the data pointed to a number of things in regards to the time and elevation mask influence. During the morning sessions the fifteen and thirty  five kilometer baselines exhibited better performance, while conversely the five and twenty five kilometer baselines performed best in the afternoon. In regards to elevation mask, little influence was found at the five kilometer baseline length, whoever the 10° displayed the best performance at the remaining baseline lengths.

  • 43.
    Eshagh, Mehdi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University West, Division of Surveying Engineering.
    Alizadeh Khameneh, Mohammad Amin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The effect of constraints on bi-objective optimisation of geodetic networks2015In: Acta Geodaetica et Geophysica, ISSN 2213-5820, Vol. 50, no 4, p. 449-459Article in journal (Refereed)
    Abstract [en]

    One of the problems in the single-objective optimisation models (SOOMs) foroptimising geodetic networks is the contradiction of the controlling constraints, which maylead to their violation or infeasibility in the optimisation process. One way to solve thisproblem is to use a bi-objective optimisation model (BOOM) instead of SOOMs. In thispaper, we will use the BOOM of precision and reliability and investigate the influence ofthe controlling constraints in a two-dimensional simulated network. Our studies show thatthe unconstrained BOOM is a good model, which almost fulfils our precision and reliabilitydemands of the network. This model is also economical as more observables are removedfrom the plan whilst adding the controlling constraints leads to including more observables,which have no significant role.

  • 44.
    Eshagh, Mehdi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University West, Sweden.
    Alizadeh Khameneh, Mohammad Amin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Two-epoch optimal design of displacement monitoring networks2015In: Boletim de Ciências Geodésicas, ISSN 1413-4853, E-ISSN 1982-2170, Vol. 21, no 3, p. 484-497Article in journal (Refereed)
    Abstract [en]

    In the traditional method of optimal design of displacement monitoring networks a higher precision,  times better than the desired accuracy of displacements, is considered for the net points in such a way that the accuracy of the detected displacements meets the desired one. However, in this paper, we develop an alternative method by considering the total number of observations in two epochs without such a simple assumption and we call it two-epoch optimisation. This method is developed based on the Gauss-Helmert adjustment model and the variances of the observations are estimated instead of the weights to optimise the observation plan. This method can deliver the same results as the traditional one, but with less required observations in each epoch.

  • 45.
    Eshagh, Mehdi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Univ West, Sweden.
    Zoghi, Sedigheh
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Local error calibration of EGM08 geoid using GNSS/levelling data2016In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 130, p. 209-217Article in journal (Refereed)
    Abstract [en]

    The geoid error, computed from EGM08, is unrealistically large due to the continuation of the spherical harmonic coefficient errors down to the surface of the reference ellipsoid. In this study, we try to calibrate such an error by the differences between the EGM08 and GNSS/levelling geoids over Fennoscandia. We use the variance component estimation procedure through combined adjustments of the geoid and GNSS/levelling heights using corrector surfaces of 4-, 5- and 7-parameter. We also develop a simple iterative method to calibrate the geoid error from the a posteriori variance factor and the errors of GNSS/levelling geoid. Our numerical investigations show that performing the separate adjustment and variance component estimation for each country with a two component stochastic model is more successful than performing it in the whole area with a five-component model. The number of GNSS/levelling data over Sweden and Norway are much larger than those in Denmark and Finland. This causes that the corrector surfaces are fitted better in these countries and consequently the estimated errors for the geoid become larger than what they should be in the others. Based on a 7-parameter corrector surface model, the average error of the EGM08 geoid becomes 12,17, 51 and 34 mm, in Sweden, Denmark, Norway and Finland, respectively. If the two-component stochastic model is used in a combined adjustment over Fennoscandia this average error will be 48 mm.

  • 46.
    Gustafsson, Hanna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Zuna, Lea
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Unmanned Aerial Vehicles for Geographic Data Capture: A Review2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In GIS-projects the data capture is one of the most time consuming processes. Both how to collect the data and the quality of the collected data is of high importance. Common methods for data capture are GPS, LiDAR, Total Station and Aerial Photogrammetry. Unmanned Aerial Vehicles, UAVs, have become more common in recent years and the number of applications continues to increase. As the technique develops there are more ways that UAV technique can be used for collection of geographic data. One of these techniques is the UAV photogrammetry that entails using an UAV equipped with a camera combined with photogrammetric software in order to create three dimensional models and orthophotos of the ground surface.

    This thesis contains a comparison between different geographic data capture methods such as terrestrial and aerial methods as well as UAV photogrammetry. The aim is to investigate how UAVs are used to collect geographic data today as well how the techniques involving UAVs can replace or be used as a complement to traditional methods.

    This study is based on a literature study and interviews. The literature study aims to give a deeper insight in where and how UAVs are used today for geographic data capturing with focus on three main areas: environmental monitoring, urban environment and infrastructure, and natural resources. Regarding the interviews companies and other participants using UAVs for geographic data collection in Sweden have been interviewed to get an accurate overview of the current status regarding the use of UAVs in Sweden. Advantages, disadvantages, limitations, economical aspects, accuracy and possible future use or development are considered as well as different areas of applications.

    The study is done in collaboration with the geographic IT company Digpro Solutions AB. The goal is to be able to present suggestions of how UAV data can be applied in Digpros applications.

    Information from the literature study and the interviews show that using a UAV makes it possible to cover a large range between terrestrial and aerial methods, and that it can replace or complement other methods for surveying and data collection. The use gives the possibility to get close to the object without being settle to the ground, as well as work environment profits since dangerous, difficult areas can be accessed from distance. The data can be collected faster, quicker, cheaper and more frequent. Time savings occurs in the measurement stage but compared to terrestrial methods more time is required for the post-processing of the data. The use in Sweden is limited due to difficulties linked to Swedish legislation regarding camera surveillance, as well as long waiting times for the permissions that is required to fly. However, a change in the camera surveillance law is expected which means that UAVs will be excluded from the law. That may result in great benefits for everyone within the industry as well as a continued development of the technique and the use of UAVs.

  • 47.
    Haque, Md Ubydul
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Mapping malaria vector habitatsin the dry season in Bangladeshusing Spot imagery2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Malaria is a major disease burden in the southeast part (Rangamati, Khagracharia andBandarban) of Bangladesh. This study uses satellite based data obtained from SPOT-5 forinvestigating association between land cover patterns and malaria incidences in an area of thatpart of Bangladesh. Climatic conditions were also examined to determine its influence onmosquito breeding and malaria incidences. Unsupervised classification was performed usingground-truth data to classify the land cover patterns of the area; and NDVI of the area wascomputed. Overall accuracies of 89.9%, 87.9% and 89.5% were achieved in Kuhalong,Shuloka and Bandarban respectively. These data sets were used to predict risk for malariautilizing statistical tools of the SPSS software. Factor analysis was carried out to investigaterelationship between land cover patterns and malaria cases in the different subunits (calledunions) of the study area. Malaria cases were not evenly distributed among the unions. InKuhalong union, there were more malaria cases compared to the other unions, Shuloka andBandarban. Kuhalong is covered with more water bodies than that in the other two unions.The results of the analysis illustrate malaria cases are correlated with land cover like water,light forest, and agricultural land; and are also associated with average humidity and averageNDVI.

  • 48.
    Horemuz, Milan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Andersson, Johan Vium
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Geodesy (closed 20110301).
    Polynomial interpolation of GPS satellite coordinates2006In: GPS Solutions, ISSN 1080-5370, E-ISSN 1521-1886, Vol. 10, no 1, p. 67-72Article in journal (Refereed)
    Abstract [en]

    This article describes an algorithm for polynomial interpolation of GPS satellite coordinates and its implementation in MATLAB. The algorithm is intended for realtime processing software and computes the position and velocity of GPS satellites from both broadcast and precise ephemerides. Tests with different orders of polynomials, and with different time spans used for polynomial fitting, show suitable settings with respect to the required interpolation precision.

  • 49.
    Horemuz, Milan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jansson, Patric
    Optimal placering av en totalstation2016In: SINUSArticle in journal (Other (popular science, discussion, etc.))
  • 50.
    Horemuz, Milan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jansson, Patric
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimum Establishment of Total Station2016In: Journal of Surveying Engineering, ISSN 0733-9453, E-ISSN 1943-5428, Vol. 143, no 2Article in journal (Refereed)
    Abstract [en]

    At least two control points (CPs) must be available to determine the position and orientation of a total station (TS). This paper analyzes the optimum horizontal location of the TS with respect to the CPs and answers the question: What is the best location of the TS with respect to the CPs if the goal is to determine the coordinates of the TS and detail points (DPs) as precisely as possible? The optimality is based on the uncertainty of the horizontal coordinates of the TS and of the points measured from it, as well as on the uncertainty of the TS orientation. The investigation of this optimality problem was performed both analytically and by the trial-and-error method. It was found that the optimum location of TS is in the center of gravity of all CPs. For a given configuration of the control and DPs, the location of the TS does not influence significantly the positional uncertainty of the surveyed DPs.

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