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  • 151.
    Jacob, Alexander
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Urban land cover mapping with TerraSAR-X using an edge-aware region-growing and merging algorithm2014In: 2014 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), IEEE , 2014, p. 4836-4839Conference paper (Refereed)
    Abstract [en]

    TerraSAR X data has been analyzed for its suitability of urban land cover mapping using our recently developed object based image analysis tool KTH-SEG, which is based on an edge aware region growing and merging algorithm and a support vector machine classifier. Classification results over the Shanghai International Airport area using 8 classes, Water, Grass, Roads, Buildings, Crops, Forest, Bare Crops and Green Houses have proven with an overall accuracy just shy of 84% that this is very well the case. It has further been investigated which segment sizes and image configuration yield the best results.

  • 152.
    Jansson, Patric
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Persson, Clas-Göran
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Om osäkerheten i arealbestämningar2013Report (Other academic)
    Abstract [en]

    This report gives a thorough description of the determination of two-dimensional areas and the estimation of area uncertainty. Considering the formulas for area determination, the basis is regular shapes, e.g. triangles, squares, rectangles, rhombs and regular (closed) polygons. The given formulas are valid as such; however, they also tell us how they can be simplified. The report presents strict as well as approximate formulas for area uncertainty estimates.          

    The approach is mainly from a statistical point of view. However, there are some geometric factors/ variations which have an influence on the size of the area. They are dealt with by mathematical means.

    In addition, less mathematical, more argument-based (philosophical) descriptions of other “areal defects”, having an influence on the area uncertainty, are presented. Examples of these defects are given to illustrate their impact on area uncertainty estimation.

  • 153.
    Jansson, Patric
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Persson, Clas-Göran
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    The effect of correlation on uncertainty estimates – with GPS examples2013In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 3, no 2, p. 111-120Article in journal (Refereed)
    Abstract [en]

    This article deals with the effect of correlation on the estimates of measurement uncertainty, with some focus on Global Positioning Satellite (GPS) time series analysis. Analytical derivations and Monte Carlo simulations form the theoretical basis, which shows that uncompensated correlation produces unrealistic uncertainty estimates. Tools for handling correlation in connection with estimation of uncertainty, construction of confidence intervals, hypothesis testing, design of measurement strategies, and development of tolerances are outlined and demonstrated. The GPS observation time series used in the article has a short to medium range correlation, and can therefore be handled with the presented tools - based on a simple Location-model and stationary stochastic processes.

  • 154.
    Jansson, Patric
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Persson, Clas-Göran
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Uncertainty in area determination2014Report (Other academic)
    Abstract [en]

    This report gives a thorough description of the determination of two-dimensional areas and the estimation of area uncertainty. Considering the formulas for area determination, the basis is regular shapes, e.g. triangles, squares, rectangles, rhombi and regular (closed) polygons. The given formulas are valid as such; however, they also indicate how they can be simplified. The report presents strict as well as approximate formulas for area uncertainty estimates.          

    The approach is mainly from a statistical point of view. However, there are some geometric factors/ variations which have an influence on the size of the area. They are dealt with by mathematical means.

    In addition, less mathematical, more argument-based (philosophical) descriptions of other “areal defects”, having an influence on the area uncertainty, are presented. Examples of these defects are given to illustrate their impact on uncertainty estimation.

    The report is mainly an English translation of an earlier Swedish report [1]. Therefore, some minor parts refer to Swedish conditions – e.g. regarding coordinate systems, map projections etc.

  • 155.
    Jia, Tao
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Geospatial Knowledge Discovery using Volunteered Geographic Information: a Complex System Perspective2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The continuous progression of urbanization has resulted in an increasing number of people living in cities or towns. In parallel, advancements in technologies, such as the Internet, telecommunications, and transportation, have allowed for better connectivity among people. This has engendered drastic changes in urban systems during the recent decades. From a social geographic perspective, the changes in urban systems are primarily characterized by intensive contacts among people and their interactions with the surrounding urban environment, which further leads to subsequent challenging problems such as traffic jams, environmental pollution, urban sprawl, etc. These problems have been reported to be heterogeneous and non-deterministic. Hence, to cope with them, massive amounts of geographic data are required to create new knowledge on urban systems.

    Due to the thriving of Volunteer Geographic Information (VGI) in recent years, this thesis presents knowledge on urban systems based on extensive VGI datasets from three sources: highway dataset from the OpenStreetMap (OSM) project, photo location dataset from the Flickr website, and GPS tracking datasets from volunteers, taxicabs, and air flights. The knowledge primarily relates to two issues of urban systems: the urban space and the corresponding human dynamics. In accordance, on one hand, urban space acts as a carrier for associated geographic activities and knowledge of it benefits our understanding of current social and economic problems in urban systems. On the other hand, human dynamics reflect human behavior in urban space, which leads to complex mobility or activity patterns. Its investigation allows a derivation of the underlying driving force that is very instructive to urban planning, traffic management, and infectious disease control. Therefore, to fully understand the two issues, this thesis conducts a thorough investigation from multiple aspects.

    The first issue is investigated from four aspects. First, at the city level, the controversial topic of city size regularity is investigated in terms of natural cities, and the conclusion is that Zipf’s law holds stably for all US cities. Second, at the sub-city level, the size distribution of spatial units within different cities in terms of the clusters formed by street nodes, photo locations, and taxi static points are explored, and the result shows a remarkable scaling property of these spatial units. Third, enlightened by the scaling property of the urban space at the city or sub-city level, this thesis devises a novel tool that can demarcate the cities into three categories: compact cities, normal cities, and sprawling cities. The tool is then applied to cities in both the US and three European countries. In the last, another representation of urban space is taken into account, namely the transportation network. The findings report that the US airport network displays the properties of scale-free, small-world, and disassortative mixing and that the individual natural airports show heterogeneous patterns that are probably subject to geographic constraints and socioeconomic factors.

    The second issue is examined from four perspectives. First, at the city level, the movement flow contributed by agents using two types of behavior is investigated through an agent-based simulation, and the result conjectures that the human mobility behavior is mainly shaped by the underlying street network. Second, at the country level, this thesis reports that the human travel length by air can be approximated well by an exponential distribution, and subsequent simulations indicate that human mobility behavior is largely constrained by the underlying airport network. Third, at the regional level, the length that humans travel by car is demonstrated to agree well with a power law with exponential cutoff distribution, and subsequent simulation further reproduces this levy flight characteristic. Based on the simulation, human mobility behavior is again revealed to be primarily shaped by the underlying hierarchical spatial structure. Finally, taxicab static points are adopted to explore human activity patterns, which can be characterized as the regularities in space and time, the heterogeneity and predictability in space.

    From a complex system perspective, this thesis presents the knowledge discovered in urban systems using massive volumes of geographic data. Together with new knowledge from empirical findings, the development of methods, and the design of theoretic models, this thesis also shares the research community with geographic data generated from extensive VGI datasets and the corresponding source codes. Moreover, this study is aligned with a paradigm shift in that it analyzes large-size datasets using high processing power as opposed to analyzing small-size datasets with low processing power.

  • 156.
    Jia, Tao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Jiang, B.
    Building and analyzing the US airport network based on en-route location information2012In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 391, no 15, p. 4031-4042Article in journal (Refereed)
    Abstract [en]

    From a complex network perspective, this study sets out two aims around the US airport network (USAN) which is built from en-route location information of domestic flights in the US. First, we analyze the structural properties of the USAN with respect to its binary and weighted graphs, and second we explore the airport patterns, which have wide-ranging implications. Results from the two graphs indicate the following. (1) The USAN exhibits scale-free, small-world and disassortative mixing properties, which are consistent with the mainstream perspectives. Besides, we find (2) a remarkable power relationship between the structural measurements in the binary graph and the traffic measurements in the weighted counterpart, namely degree versus capacity and attraction versus volume. On the other hand, investigation of the airport patterns suggests (3) that all the airports can be classified into four categories based on multiple network metrics, which shows a complete typology of the airports. And it further indicates (4) that there is a subtle relationship between the airport traffic and the geographical constraints as well as the regional socioeconomic indicators.

  • 157.
    Jia, Tao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Jiang, Bin
    University of Gävle.
    Carling, Kenneth
    Dalarna University.
    Bolin, Magnus
    Dalarna University.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    An empirical study on human mobility and its agent-based modeling2012In: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, Vol. 2012, no 11, p. P11024-Article in journal (Refereed)
    Abstract [en]

    This paper aims to analyze the GPS traces of 258 volunteers for a better understanding of both the human mobility patterns and the mechanism. We report the regular and scaling properties of human mobility from several aspects, and importantly we identify its levy flight characteristic which is consistent with the previous studies. We further assume two factors that may govern the levy flight property: (1) the scaling and hierarchical properties of the purpose clusters which serve as the underlying spatial structure, and (2) the individual preferential behavior. To verify the assumptions, we implement an agent-based model with the two factors, and the simulated results indeed capture the same levy flight pattern as the observed one. In order to enable the model to reproduce more mobility patterns, we add the model a third factor, the jumping factor which means the probability that one person may cancel the regular mobility schedule and explore a random place. With this factor, our model could cover a relatively wide range of human mobility patterns with scaling exponent values from 1.55 to 2.05.

  • 158.
    Jia, Yanjing
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Object-based Land Cover Classification with Orthophoto and LIDAR Data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Image classification based on remotely sensed data is the primary domain of automatic mapping research. With the increasing of urban development, keeping geographic database updating is imminently needed. Automatic mapping of land cover types in urban area is one of the most challenging problems in remote sensing. Traditional database updating is time consuming and costly. It has usually been performed by manual observation and visual interpretation, In order to improve the efficiency as well as the accuracy, new technique in the data collection and extraction becomes increasingly necessary. This paper studied an object-based decision tree classification based on orthophoto and lidar data, both alone and integrated. Four land cover types i.e. Forest, Water, Openland as well as Building were successfully extracted. Promising results were obtained with the 89.2% accuracy of orthophoto based classification and 88.6% accuracy of lidar data based classification. Both lidar data and orthophoto showed enough capacity to classify general land cover types alone. Meanwhile, the combination of orthophoto and lidar data demonstrated a prominent classification results with 95.2% accuracy. The results of integrated data revealed a very high agreement. Comparing the process of using orthophoto or lidar data alone, it reduced the complexity of land cover type discrimination. In addition, another classification algorithm, support vector machines (SVM) classification was preformed. Comparing to the decision tree classification, it obtained the same accuracy level as decision tree classification in orthophoto dataset (89.2%) and integration dataset (97.3%). However, the SVM results of lidar dataset was not satisfactory. Its overall accuracy only reached 77.1%. In brief, object-based land cover classification demonstrated its effectiveness in land cover map generation. It could exploit spectral and spatial features from input data efficiently and classifying image with high accuracy. 

  • 159.
    Jiang, Bin
    et al.
    Geomatics, University of Gävle.
    Liu, Xintao
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    AxialGen: A research prototype for automatically generating the axial map2009Conference paper (Refereed)
    Abstract [en]

    AxialGen is a research prototype for automatically generating the axial map, which consists of the least number of the longest visibility lines (or axial lines) for representing individual linearly stretched parts of open space of an urban environment. Open space is the space between closed spaces such as buildings and street blocks. This paper aims to provide an accessible guide to software AxialGen, and the underlying concepts and ideas. We concentrate on the explanation and illustration of the key concept of bucket: its definition, formation and how it is used in generating the axial map. 

  • 160.
    Jing, Sun
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Semi-automated rapid damage assessment usinghigh-resolution satellite imagery: a case study of the 2008 Wenchuanearthquake, China2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 161.
    Jonasson, Sara
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Jämförelse av objekt-orienterad ECHO med Pixelbaserad MLC för klassificering av fjärranalysdata2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 162. Jun, Chen
    et al.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Li, Songnian
    China: Open access to Earth land-cover map2014In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 514, no 7523, p. 434-434Article in journal (Refereed)
  • 163. Kawakami, Naomi
    et al.
    Winkleby, Marilyn
    Skog, Lars
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Szulkin, Robert
    Sundquist, Kristina
    Differences in neighborhood accessibility to health-related resources: A nationwide comparison between deprived and affluent neighborhoods in Sweden2011In: Health and Place, ISSN 1353-8292, E-ISSN 1873-2054, Vol. 17, no 1, p. 132-139Article in journal (Refereed)
    Abstract [en]

    This nationwide Swedish study used geocoded data from all businesses in Sweden to examine the distribution of 12 main categories of goods, services, and resources in 6986 neighborhoods, categorized as low, moderate, and high neighborhood deprivation. The main findings were that high- and moderate-deprivation neighborhoods had a significantly higher prevalence of all types of goods, services, and resources than low-deprivation neighborhoods. These findings do not support previous research that hypothesizes that poorer health among people in deprived neighborhoods is explained by a lack of health-promoting resources, although a higher presence of health-damaging resources may play a role. (C) 2010 Elsevier Ltd. All rights reserved.

  • 164. Kiamehr, R.
    et al.
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Salkhordeh, S.
    Combination of satellite altimetry data and EGM2008 model for evaluation of the height datum in Iran2011In: Ecology, Environment and Conservation, ISSN 0971-765X, Vol. 17, no 4, p. 653-659Article in journal (Refereed)
    Abstract [en]

    The repetitive periodic coverage from Topex/Poseidon altimetry satellite during 1992-2003 from the Oman Sea and Persian Gulf were used to prepare time series covering the study area. The linear portion of series were analyzed to calculate mean sea level as its temporal changes using the least-squares method. Due to the significance of sea level topography in oceanographic studies a new model proposed using the combined altimetry satellite data and the EGM2008 global geoid model in order to determine and equalize the current height datum for Iran. The maximum and minimum of sea surface topography vary within the range of -0.7 to 1.1m in the study area. Adjustment of the current precise network for Iran established based on the Bandar Abbas tide gauge station, which its corresponding SST estimated up to -0.5 m. Effect of such large systematic error in national height system cannot be ignored in geodynamical and engineering researches.

  • 165.
    Kiamehr, Ramin
    et al.
    Department of Geodesy and Geomatics, Zanjan University, Iran).
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Estimating variance components of ellipsoidal, orthometric and geoidalheights through the GPS/levelling Network in Iran2008In: Journal of the Earth and Space Physics, ISSN 0378-1046, Vol. 34, no 3, p. 1-13Article in journal (Refereed)
    Abstract [en]

    The Best Quadratic Unbiased Estimation (BQUE) of variance components in the Gauss-Helmert model is used to combine adjustment of GPS/levelling and geoid to determinethe individual variance components for each of the three height types. Through theresearch, different reasons for achievement of the negative variance components werediscussed and a new modified version of the Best Quadratic Unbiased Non-negativeEstimator (MBQUNE) was successfully developed and applied. This estimation could beuseful for estimating the absolute accuracy level which can be achieved using theGPS/levelling method. A general MATLAB function is presented for numericalestimation of variance components by using the different parametric models. Themodified BQUNE and developed software was successfully applied for estimating thevariance components through the sample GPS/levelling network in Iran. In the followingresearch, we used the 75 outlier free and well distributed GPS/levelling data. Threecorrective surface models based on the 4, 5 and 7 parameter models were used throughthe combined adjustment of the GPS/levelling and geoidal heights. Using the 7-parametermodel, the standard deviation indexes of the geoidal, geodetic and orthometric heights inIran were estimated to be about 27, 39 and 35 cm, respectively.

  • 166.
    Kolehmainen, Karoliina
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    MULTITEMPORAL SPOT IMAGES FOR URBAN LAND-COVER CHANGE DETECTION OVER STOCKHOLM BETWEEN 1986 AND 20042008In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2008Conference paper (Other academic)
    Abstract [en]

     The overall objective of this research is to detect new urban areas over Stockholm Region between 1986 and 2004 using multitemporal remote sensing. Two SPOT images acquired on 13th of June 1986 and 29th of July 2004 were used for changed detection. Three change detection methods were tested for this purpose: image differencing, principal component analysis and change vector analysis using normalised difference vegetation index and brightness index. The results showed that image differencing using the red bands and second principle components performed better in detecting new urban features than change vector analysis (the overall accuracies: 89%, 87% and 83% respectively & kappa: 0.77, 0.74 and 0.67). Even though overall accuracies are all above 80%, the kappa coefficients were much lower indicating substantial amount of omission and commission errors presented in the change maps.

  • 167. Kuang, W.
    et al.
    Liu, J.
    Shao, Q.
    He, J.
    Sun, C.
    Tian, H.
    Ban, Yifahg
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Dynamic urban growth model at regional scale and its application2011In: Acta Geographica Sinica, ISSN 0375-5444, Vol. 66, no 2, p. 178-188Article in journal (Refereed)
    Abstract [en]

    Dynamic urban expansion simulation at regional scale is one of the important research methodologies in Land Use/Cover Change (LUCC) and global environmental change influenced by urbanization. However, previous studies indicate that the single urban expansion simulation for future scenarios at local scale cannot meet the requirements for characterizing and interpreting the interactive mechanisms of regional urbanization and global environmental change. This study constructed a regional Dynamic Urban Expansion Model (Reg-DUEM) suitable for different scenarios by integrating the Artificial Neural Network (ANN) and Cellular Automaton (CA) model. Firstly we analyzed the temporal and spatial characteristics of urban expansion and acquired a prior knowledge rules using land use/cover change datasets of Beijing-Tianjin-Tangshan metropolitan area. The future urban expansion under different scenarios is then simulated based on a baseline model, economic models, policy models and the structural adjustment model. The results indicate that Reg-DUEM has good reliability for a non-linear expansion simulation at regional scale influenced by macro-policies. The simulating results show that future urban expansion patterns from different scenarios of the metropolitan area have the tremendous spatio-temporal differences. Future urban expansion will shift quickly from Beijing metropolis to the periphery of Tianjin and Tangshan city along coastal belt.

  • 168.
    LAU, SIN WAI
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Comparison and Fusion of space borne L-, C- and X- Band SAR Images for Damage Identification in the 2008 Sichuan Earthquake2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Remote sensing has been widely used in disaster management. However, application of optical imageries in damage detection is not always feasible for immediate damage assessment. In the case of the Sichuan earthquake in 2008, the damaged areas were covered by cloud and fog for most of the time. The all weather SAR imageries could instead provide information of the damaged area. Therefore, more efforts are needed to explore the usability of SAR data. In regards to this purpose, this research focuses on studying the ability of using various SAR data in damage identification through image classification, and furthermore the effectiveness of fusion of various sensors in classification is evaluated.

     

    Three different types of SAR imagery were acquired over the heavily damaged zone Qushan town in the Sichuan earthquake. The 3 types of SAR data are ALOS PALSAR L-band, RADARSAT-1 C-band and the TerraSAR-X X- band imageries.

     

    Maximum likelihood classification method is applied on the imageries.  Four classes: Water, collapsed area, built-up area and landslide area are defined in the study area. The ability of each band in identifying these four classes is studied and the overall classification accuracy is analysed. Furthermore, fusion of these 3 types of imageries is performed and the effectiveness and accuracy of image fusion classification are evaluated.

     

    The results show that classification accuracy from individual SAR imagery is not ideal. The overall accuracy which PALSAR gives is 30.383%, RADARSAT-1 is 31.268% while TerraSAR-X only achieves 37.168%. Accuracy statistics demonstrate that TerraSAR-X performs the best in classifying these four classes.

     

    SAR image fusion shows a better classification result. Double image fusion of PALSAR and RADARSAT-1, PALSAR and TerraSAR-X, and RADARSAT-1 and TerraSAR-X give an overall classification accuracy of 41.88%, 42.478% and 37.758% respectively. The result from triple image fusion even reaches 52.507%. They are all higher than the result given by the individual images.

     

    The study illustrates that the VHR TerraSAR X band SAR data has a higher ability in classification of damages, and fusion of different band can improve the classification accuracy. 

  • 169. Lewerin, Susanna Sternberg
    et al.
    Skog, Lars
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Frossling, Jenny
    Wahlstrom, Helene
    Geographical distribution of salmonella infected pig, cattle and sheep herds in Sweden 1993-20102011In: Acta Veterinaria Scandinavica, ISSN 1751-0147, E-ISSN 1751-0147, Vol. 53, p. 51-Article in journal (Refereed)
    Abstract [en]

    Background: The Swedish salmonella control programme covers the entire production chain, from feed to food. All salmonella serotypes are notifiable. On average, less than 20 cases of salmonella in food-producing animals are reported every year. In some situations, the cases would be expected to cluster geographically. The aim of this study was to illustrate the geographic distribution of the salmonella cases detected in pigs, cattle and sheep. Methods: Data on all herds with pigs, cattle and sheep found to be infected with salmonella during the time period from 1993 to 2010 were obtained from the Swedish Board of Agriculture. Using the ArcGIS software, various maps were produced of infected herds, stratified on animal species as well as salmonella serotype. Based on ocular inspection of all maps, some were collapsed and some used separately. Data were also examined for temporal trends. Results: No geographical clustering was observed for ovine or porcine cases. Cattle herds infected with Salmonella Dublin were mainly located in the southeast region and cattle herds infected with Salmonella Typhimurium in the most southern part of the country. Some seasonal variation was seen in cattle, but available data was not sufficient for further analyses. Conclusions: Analyses of data on salmonella infected herds revealed some spatial and temporal patterns for salmonella in cattle. However, despite using 18 years' of data, the number of infected herds was too low for any useful statistical analyses.

  • 170.
    Li, Nuosuola
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Large-Scale Realistic Macro-Simulation of Vehicle Movement on Road Networks2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 171.
    Li, Yuheng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Zhang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Spatial-temporal arable and builtland use change in Beijing-Tianjin-Hebei Metropolitan Region: 1990-20052011Conference paper (Refereed)
    Abstract [en]

    The paper investigates land use change at the county level in Beijing-Tianjin-Hebei Metropolitan Region. Unlike previous studies which merely divided the region according to the administrations, the paper identifies three land use patterns in terms of urban-rural resource flows: urban, peri-urban and periphery areas. Research findings show that the change of arable land and built land in the urban areas is faster than that in the peri-urban and periphery areas. Land use change rates in the period of 2000-2005 increased comparing with that in the period of 1990-2000. Regression analysis also shows the changes of driving factors to the land use change in the three patterns in the two research periods. The paper concludes through emphasizing the role of peri-urban areas as the urban-rural interface to coordinate land use in the urban areas and periphery areas in this region.

  • 172.
    Lin, Jingyi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Distance Dependence in the Spatial Structure of China’s Aviation System: A complex network perspective2011Conference paper (Other academic)
  • 173.
    Lin, Jingyi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Network analysis of China's aviation system, statistical and spatial structure2012In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 22, p. 109-117Article in journal (Refereed)
    Abstract [en]

    Aviation systems are less geographically constrained compared to ground transportation because their routes are not so affected by geographical conditions. For this reason, aviation systems are endowed to some extent with a distinctive network topology and spatial pattern. In this article, the statistical features of China’s aviation system (CAS) are investigated through a complex network approach by examining weekly flight patterns. The correlation study proves the existence of a spatial hierarchical structure within China’s aviation network, which implies a more complex spatial mechanism. Subsequently the spatial structure of CAS is explored based on the flight distances between airport cities. In light of three measurements of node strength, population and GDP, It has been decided that the spatial effect of China’s aviation system should be analyzed separately in term of different distance scales. Only for medium- and long-distance travel, the flight patterns conform to a gravitation law; therefore, the distance dependence function can be generalized as a scaling relationship. In summary, from a complex network angle, this paper provides preliminary but enlightening insights to understanding the unique spatial mechanism of aviation systems.

  • 174.
    Lin, Jingyi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Complex Network Topology of Transportation Systems2013In: Transport reviews, ISSN 0144-1647, E-ISSN 1464-5327, Vol. 33, no 6, p. 658-685Article in journal (Refereed)
    Abstract [en]

    As a strategic factor for a country to survive in the global competition, transportation systems have attracted extensive attention from different disciplines for a long time. Since the introduction of complex network theory in the last decade, however, studies on transport systems have witnessed dramatic progress. Most roads, streets, and rails are organized as a network pattern, while link flows, travel time, or geographical distance are regarded as weights. In this article, the authors will present the current state of topological research on transportation systems under a complex network framework, as well as the efforts and challenges that have been made in the last decade. First, different kinds of transportation systems should be generalized as networks in different ways, which will be explained in the first part of this paper. We follow this by summarizing network measures that describe topological characteristics of transportation networks. Then we discuss the empirical observations from the last decade on real transportation systems at a variety of spatial scales. This paper concludes with some important challenges and open research frontiers in this field.

  • 175.
    Lin, Xing
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Modern GIR Systems: Framework, Retrieval Model and Indexing Techniques2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Geographic information is one of the most important and the most common types of information in human society. It is estimated that more than 70% of all information in the world has some kind of geographic features. In the era of information explosion, information retrieval (IR) tools, such as search engines, are the main tools people used to quickly find the information they need nowadays. Because of the importance of geographic information, recent efforts have been made either by expanding the traditional IR to support a spatial query, or building a GIR in a brand new architecture from the ground such as the SPIRIT project. To some degree, these existing GIR systems could solve users’ information search need with a spatial filter, especially when the users are looking for information on something within a relatively large extent.Despite its advantage on processing geographical information and queries over conventional IR systems, modern GIR systems are also facing challenges including a proper representation and extraction of geographical information within documents, a better information retrieval model for both thematic and geographical information, a fast indexing mechanism for rapid search within documents by thematic and geographical hints, and even a new architecture of system.The objective of this licentiate research is to provide solutions to some of these problems in order to build a better modern GIR system in the future. The following aspects have been investigated in the thesis: a generic conceptual framework and related key technologies for a modern GIR system, a new information retrieval model and algorithm for measuring the relevance scores between documents and queries in GIR, and finally a new better indexing technique to geographically and thematically index the documents for a faster query processing within modern GIR.Concerning the proposed conceptual framework for modern GIR, it includes three modules: (1) the user interface module, (2) the information extractor, storage and indexer module and (3) the query processing and information retrieval module. Two knowledge bases, Gazetteer and Thesaurus, play an important role in the proposed framework. A digital map based user interface is proposed for the input of user information search needs and representation of retrieval results. Key techniques required for the implementation of a modern GIR using the proposed framework are a proper representation of document and query information, a better geographical information extractor, an innovative information retrieval model and relevance ranking algorithm, and a combined indexing mechanism for both geographical and thematic information.The new information retrieval model is established based on a Spatial Bayesian Network consisting of place names appeared in a single document and the spatial relationships between them. The new model assesses the geographical relevance between GIR document and query by the geographical importance and adjacency of the document geo-footprint versus the geographical scope of the user’s query.Regarding the indexing mechanism for modern GIR systems, a Keyword-Spatial Hybrid Index (KSHI) is proposed for the single and overall geo-footprint model, in which there is only one single geo-footprint for each document to retrieve from. A Keyword-Spatial Dual Index (KSDI) is proved to be more appropriate for a GIR system which allows for multiple geo-footprints within a single document.In addition to theoretical analysis, necessary experiments have also been carried out to evaluate the efficiency of proposed new information retrieval model and indices. Both the theoretical analysis and results of experiments show the potentials of proposed solution and techniques.

  • 176.
    Lin, Xing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Yu, Bo
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    On Indexing Mechanism in Geographical Information Retrieval System2007In: 10th AGILE International Conference on Geographic Information Science 2007, 2007Conference paper (Refereed)
  • 177. Liu, J.
    et al.
    Bi, H.
    Zhu, P.
    Sun, Jing
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Zhu, J.
    Chen, T.
    Estimating stand volume of Xylosma racemosum forest based on texture parameters and derivative texture indices of ALOS imagery2014In: Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery, ISSN 1000-1298, Vol. 45, no 7, p. 245-254Article in journal (Refereed)
    Abstract [en]

    The Xylosma racemosum forest located in Huairou District of Beijing was chosen as research objects, texture parameters as well as derivative texture indices of different window sizes from ALOS fusion imagery with resolution of 2.5 m were measured. Stepwise multiple regression models were developed to describe the relationship between textures (including texture parameters and derivative texture indices) and field measurements of stand volume. The main objective was to compare estimation accuracy between model established by texture parameters and that by derivative texture indices, select the most effective Xylosma racemosum stand volume estimate model and select the most effective window size. Results indicate that the value of adjusted R2 of fitting models established by derivative texture indices were better than those of texture parameters at the same window size, the value of adjusted R2 of stand volume model could be improved significantly by combination of texture parameters and derivative texture indices at the same window size, the optimal estimation model of Xylosma racemosum stand volume was obtained when all of the texture parameters and derivative texture indices of all window sizes were introduced into stepwise multiple regression, 11×11 was the optimal window size with the largest adjusted R2 for fitting Xylosma racemosum stand volume by texture parameters and derivative texture indices generated at one single window size.

  • 178. Liu, Jiyuan
    et al.
    Zhang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Hu, Yunfeng
    Regional differences of China's urban expansion from late 20th to early 21st century based on remote sensing information2012In: Chinese Geographical Science, ISSN 1002-0063, Vol. 22, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    This study investigated the regional differences of China's urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China's land cover/land use database) datasets which were mainly produced from remote sensing imagery data. A newly defined urbanization level index (UI), based on urban land area, is proposed to describe Chinese urban expansion process at 1 kilometer, provincial, regional, and national scales, together with the absolute urban expansion index (UE(a)) and the relative urbanization expansion index (UE(r)). The results indicate that the percentages of total land area occupied by urban in the late 1980s, 1995, 2000, 2005, and 2008 were approximately 0.25%, 0.32%, 0.33%, 0.43% and 0.52% of China's total land area, respectively. Between the late 1980s and 2008, the total urban expansion in the mainland of China was 2.645 x 10(4) km(2), resulting in an annual urban expansion area of about 1322.7 km(2)/yr, with the UE(r) of 111.9%. This study also finds that there has been an obvious spatial gradient of urbanization ratio running from the east coast to the west inland, and the urbanization gaps among different regions have persisted over the past two decades. The study also reveals obvious temporal variations of the urbanization rates. There was very little urban growth during the period of 1995-2000 due to the governmental policy factors.

  • 179. Liu, W.
    et al.
    Yamazaki, F.
    Vu, Tuong Thuy
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Automated vehicle extraction and speed determination from quickbird satellite images2011In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 4, no 1, p. 75-82Article in journal (Refereed)
    Abstract [en]

    A new method has been developed to automatically extract moving vehicles and subsequently determine their speeds from a pair of QuickBird (QB) panchromatic (PAN) and multispectral (MS) images. Since the PAN and MS sensors of QB have a slight time lag (approximately 0.2 s), the speed of a moving vehicle can be determined from the difference in the positions of the vehicle observed in the PAN and MS images due to the time lag. An object-based approach can be used to extract a vehicle from the PAN image, which has a resolution of 0.6 m. However, it is difficult to accurately extract the position of a vehicle from an MS image because its resolution is 2.4 m. Thus, an area correlation method is proposed to determine the location of a vehicle from an MS image at a sub-pixel level. The speed of the moving vehicle can then be calculated by using the vehicle extraction results. This approach was tested on several parts of a QB image covering central Tokyo, Japan, and the accuracy of the results is demonstrated in this study.

  • 180.
    Liu, Xintao
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    The Principle of Scaling of Geographic Space and its Application in Urban Studies2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Geographic space is the large-scale and continuous space that encircles the earth and in which human activities occur. The study of geographic space has drawn attention in many different fields and has been applied in a variety of studies, including those on cognition, urban planning and navigation systems. A scaling property indicates that small objects are far more numerous than large ones, i.e., the size of objects is extremely diverse. The concept of scaling resembles a fractal in geometric terms and a power law distribution from the perspective of statistical physics, but it is different from both in terms of application. Combining the concepts of geographic space and scaling, this thesis proposes the concept of the scaling of geographic space, which refers to the phenomenon that small geographic objects or representations are far more numerous than large ones. From the perspectives of statistics and mathematics, the scaling of geographic space can be characterized by the fact that the sizes of geographic objects follow heavy-tailed distributions, i.e., the special non-linear relationships between variables and their probability.

    In this thesis, the heavy-tailed distributions refer to the power law, lognormal, exponential, power law with an exponential cutoff and stretched exponential. The first three are the basic distributions, and the last two are their degenerate versions. If the measurements of the geographic objects follow a heavy-tailed distribution, then their mean value can divide them into two groups: large ones (a low percentage) whose values lie above the mean value and small ones (a high percentage) whose values lie below. This regularity is termed as the head/tail division rule. That is, a two-tier hierarchical structure can be obtained naturally. The scaling property of geographic space and the head/tail division rule are verified at city and country levels from the perspectives of axial lines and blocks, respectively.

    In the study of geographic space, the most important concept is geographic representation, which represents or partitions a large-scale geographic space into numerous small pieces, e.g., vector and raster data in conventional spatial analysis. In a different context, each geographic representation possesses different geographic implications and a rich partial knowledge of space. The emergence of geographic information science (GIScience) and volunteered geographic information (VGI) greatly enable the generation of new types of geographic representations. In addition to the old axial lines, this thesis generated several types of representations of geographic space: (a) blocks that were decomposed from road segments, each of which forms a minimum cycle such as city and field blocks (b) natural streets that were generated from street center lines using the Gestalt principle of good continuity; (c) new axial lines that were defined as the least number of individual straight line segments mutually intersected along natural streets; (d) the fewest-turn map direction (route) that possesses the hierarchical structure and indicates the scaling of geographic space; (e) spatio-temporal clusters of the stop points in the trajectories of large-scale floating car data.

    Based on the generated geographic representations, this thesis further applies the scaling property and the head/tail division rule to these representations for urban studies. First, all of the above geographic representations demonstrate the scaling property, which indicates the scaling of geographic space. Furthermore, the head/tail division rule performs well in obtaining the hierarchical structures of geographic objects. In a sense, the scaling property reveals the hierarchical structures of geographic objects. According to the above analysis and findings, several urban studies are performed as follows: (1) generate new axial lines based on natural streets for a better understanding of urban morphologies; (2) compute the fewest-turn and shortest map direction; (3) identify urban sprawl patches based on the statistics of blocks and natural cities; (4) categorize spatio-temporal clusters of long stop points into hotspots and traffic jams; and (5) perform an across-country comparison of hierarchical spatial structures.

    The overall contribution of this thesis is first to propose the principle of scaling of geographic space as well as the head/tail division rule, which provide a new and quantitative perspective to efficiently reduce the high degree of complexity and effectively solve the issues in urban studies. Several successful applications prove that the scaling of geographic space and the head/tail division rule are inspiring and can in fact be applied as a universal law, in particular, to urban studies and other fields. The data sets that were generated via an intensive geo-computation process are as large as hundreds of gigabytes and will be of great value to further data mining studies.

  • 181.
    Liu, Xintao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Jiang, Bin
    Geomatics, University of Gävle.
    A novel approach to the identification of urban sprawl patches based on the scaling of geographic space2011In: International Journal of Geomatics and Geosciences, ISSN 0976-4380, Vol. 2, no 2, p. 415-429Article in journal (Refereed)
    Abstract [en]

    This paper introduces a novel approach to identifying urban sprawl patches based on the statistics of blocks and natural cities under the principle of scaling of geographic space. Blocks are the minimum cycles decomposed from a road network and the important geographic elements in the process of urbanization. Scaling of geographic space refers to the phenomenon that small geographic objects are far more numerous than large ones. In this study, the measurements of block area, morphology and structure are found to demonstrate scaling property and follow heavy tailed distributions. Because of this, the mean values of these measurements can clearly divide all blocks into a two-level hierarchical structure, of which each hierarchy represents different geographical implications. For instance, small blocks imply the urban area while large ones imply rural area. Based on these findings, an improved method is proposed to aggregate the small blocks into natural cities in Texas. We further identify the abnormal blocks inside the natural city of Dallas, Texas as sprawling blocks, which constitute what we call urban sprawl patches. Multiple levels of urban sprawl are classified by performing the above process iteratively. This approach provides a quantitative and natural way to assess urban sprawl in the context of the urban environment. 

  • 182.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Visualisation and Generalisation of 3D City Models2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    3D city models have been widely used in various applications such as urban planning, traffic control, disaster management etc. Efficient visualisation of 3D city models in different levels of detail (LODs) is one of the pivotal technologies to support these applications. In this thesis, a framework is proposed to visualise the 3D city models online. Then, generalisation methods are studied and tailored to create 3D city scenes in different scales dynamically. Multiple representation structures are designed to preserve the generalisation results on different level. Finally, the quality of the generalised 3D city models is evaluated by measuring the visual similarity with the original models.

     

    In the proposed online visualisation framework, City Geography Makeup Language (CityGML) is used to represent city models, then 3D scenes in Extensible 3D (X3D) are generated from the CityGML data and dynamically updated to the user side for visualisation in the Web-based Graphics Library (WebGL) supported browsers with X3D Document Object Model (X3DOM) technique. The proposed framework can be implemented at the mainstream browsers without specific plugins, but it can only support online 3D city model visualisation in small area. For visualisation of large data volumes, generalisation methods and multiple representation structures are required.

     

    To reduce the 3D data volume, various generalisation methods are investigated to increase the visualisation efficiency. On the city block level, the aggregation and typification methods are improved to simplify the 3D city models. On the street level, buildings are selected according to their visual importance and the results are stored in the indexes for dynamic visualisation. On the building level, a new LOD, shell model, is introduced. It is the exterior shell of LOD3 model, in which the objects such as windows, doors and smaller facilities are projected onto walls.  On the facade level, especially for textured 3D buildings, image processing and analysis methods are employed to compress the texture.

     

    After the generalisation processes on different levels, multiple representation data structures are required to store the generalised models for dynamic visualisation. On the city block level the CityTree, a novel structure to represent group of buildings, is tested for building aggregation. According to the results, the generalised 3D city model creation time is reduced by more than 50% by using the CityTree. Meanwhile, a Minimum Spanning Tree (MST) is employed to detect the linear building group structures in the city models and they are typified with different strategies. On the building level and the street level, the visible building index is created along the road to support building selection. On facade level the TextureTree, a structure to represent building facade texture, is created based on the texture segmentation.

     

    Different generalisation strategies lead to different outcomes. It is critical to evaluate the quality of the generalised models. Visually salient features of the textured building models such as size, colour, height, etc. are employed to calculate the visual difference between the original and the generalised models. Visual similarity is the criterion in the street view level building selection. In this thesis, the visual similarity is evaluated locally and globally. On the local level, the projection area and the colour difference between the original and the generalised models are considered. On the global level, the visual features of the 3D city models are represented by Attributed Relation Graphs (ARG) and their similarity distances are calculated with the Nested Earth Mover’s Distance (NEMD) algorithm.

     

    The overall contribution of this thesis is that 3D city models are generalised in different scales (block, street, building and facade) and the results are stored in multiple representation structures for efficient dynamic visualisation, especially for online visualisation.

  • 183.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A Dynamic Typification Method of 3D City Models using Minimum Spanning Tree2010In: Proc. 6th international conference on Geographic Information Science, 2010Conference paper (Refereed)
    Abstract [en]

    A novel method based on MST for 3D City model typification is proposed. The 3D building models in higher LODs are converted into LOD1 with simplified ground plan and height. Minimum spanning tree (MST) of the ground plan centroid is generated and divided into sub-MSTs by road network. The building lists in each sub-MST with linear structure are selected, based on which typification model is created. According to the visualization evaluation and experiments, our method can reduce the building numbers while preserve the visual similarity well for selected city area.

  • 184.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A multiple representation data structure of 3D building textures2011Conference paper (Other academic)
    Abstract [en]

    Texture is an important element for visualization of 3D city models and often takes a big proportion of the total data volume. In order to simplify 3D city model textures for dynamic visualization in different scales, a multiple representation data structure, TextureTree is proposed to store building textures in different LoDs. First, the texture image is iteratively segmented by horizontal or vertical dividing zone (edge or background from edge detection) until each sections are basically in the same color. Then textures in all sections are represented by their main color and the TextureTree is created based on the color difference between the adjacent sections. With the TextureTree, the simplified texture in different LoDs can be dynamically generated. The experiment results show that the data volume of building textures can be reduced by TextureTree while the required visual similarity is preserved.

  • 185.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Generalisation of textured 3D city models using image compression and multiple representation data structure2013In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 79, p. 68-79Article in journal (Refereed)
    Abstract [en]

    Texture is an essential part of 3D building models and it often takes up a big proportion of the data volume, thus makes dynamic visualization difficult. To compress the texture of 3D building models for the dynamic visualization in different scales, a multi-resolution texture generalization method is proposed, which contains two steps: texture image compression and texture coloring. In the first step, the texture images are compressed in both horizontal and vertical directions using wavelet transform. In the second step, TextureTreeis created to store the building color texture for the dynamic visualization from different distances. To generate TextureTree, texture images are iteratively segmented by horizontal and vertical dividing zone, e.g. edge or background from edge detection, until each section is basically in the same color. Thentexture in each section is represented by their main color and the TextureTree iscreated based on the color difference between the adjacent sections. In dynamic visualization, the suitable compressed texture images or the TextureTree nodes are selected to generate the 3D scenes based on the angle and the distance between user viewpoint and the building surface. The experimental results indicate that the wavelet based image compression and proposed TextureTree can effectively represent the visual features of the textured buildings with much less data.

  • 186.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Online Visualisation of a 3D City Model Using CityGML and X3DOM2011In: Cartographica, ISSN 0317-7173, E-ISSN 1911-9925, Vol. 46, no 2, p. 109-114Article in journal (Refereed)
    Abstract [en]

    This article proposes a novel framework for online visualization of 3D city models. CityGML is used to represent the city models, based on which 3D scenes in X3D are generated, then dynamically updated to the user side with AJAX and visualized in WebGL-supported browsers with X3DOM. The experimental results show that the proposed framework can easily be implemented using widely supported major browsers and can efficiently support online visualization of 3D city models in small areas. For the visualization of large volumes of data, generalization methods and multiple-representation data structure should be studied in future research.

  • 187.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Harrie, Lars
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    A Framework of Online 3D City Visualization using CityGML and X3D2009In: The 6th International Symposium on Digital Earth, 2009Conference paper (Refereed)
    Abstract [en]

    In this paper, a novel framework based on CityGML and X3D is proposed to support visualization of 3D City Model through Internet. In the proposed framework, the CityGML files are first parsed to acquire the city model information. Citygml4j, an open source java API, is used for this parsing. Then, the X3D representation is generated based on the city model by the proposed algorithm which can dynamically create different 3D city models according to corresponding Levels of Detail (LOD). Finally, the 3D city scene in X3D format is displayed through Internet with java applet or other X3D viewers. The Java Applets are created using the Xj3D toolkit. The preliminary experiment shows that the framework can correctly and efficiently exhibit the3D city model via Internet.

  • 188.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    A Multiple Representation Data Structure for Dynamic Visualisation of Generalised 3D City Models2011In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 66, no 2, p. 198-208Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel multiple representation data structure for dynamic visualisation of 3D city models, called CityTree, is proposed. To create a CityTree, the ground plans of the buildings are generated and simplified. Then, the buildings are divided into clusters by the road network and one CityTree is created for each cluster. The leaf nodes of the CityTree represent the original 3D objects of each building, and the intermediate nodes represent groups of close buildings. By utilizing CityTree, it is possible to have dynamic zoomfunctionality in real time. The CityTree methodology is implemented in aframework where the original city model is stored in CityGML and the CityTree is stored as X3D scenes. A case study confirms the applicability of the CityTree for dynamic visualisation of 3D city models.

  • 189.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Detection and typification of linear structures for dynamic visualization of 3D city models2012In: Computers, Environment and Urban Systems, ISSN 0198-9715, E-ISSN 1873-7587, Vol. 36, no 3, p. 233-244Article in journal (Refereed)
    Abstract [en]

    Cluttering is a fundamental problem in 3D city model visualization. In this paper, a novel method for removing cluttering by typification of linear building groups is proposed. This method works. in static as well as dynamic visualization of 3D city models. The method starts by converting building models in higher Levels of Details (LoDs) into LoD1 with ground plan and height. Then the Minimum Spanning Tree (MST) is generated according to the distance between the building ground plans. Based on the MST, linear building groups are detected for typification. The typification level of a building group is determined by its distance to the viewpoint as well as its viewing angle. Next, the selected buildings are removed and the remaining ones are adjusted in each group separately. To preserve the building features and their spatial distribution, Attributed Relational Graph (ARC) and Nested Earth Mover's Distance (NEMD) are used to evaluate the difference between the original building objects and the generalized ones. The experimental results indicate that our method can reduce the number of buildings while preserving the visual similarity of the urban areas.

  • 190.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Fan, Hongchao
    Department of Cartography, Technical University of Munich.
    Real time visualisation of 3D city models in street view based on visual salienceIn: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824Article in journal (Refereed)
    Abstract [en]

    Street level visualization is an important application of the 3D city models. Challenges in the street level visualization are the cluttering of the detailed buildings and the performance. In this paper, a novel method for street level visualization based on visual salience evaluation is proposed. The basic idea of the method is to preserve these salient buildings in a view and remove the non-salient ones. The method is composed by pre-process and real-timevisualization. The pre-process starts by converting 3D building models in higher Levels of Detail (LoDs) into LoD1 with simplified ground plan. Then a number of index view points are created along the streets; these indexes refer both to the positions and the direction of the sights. A visual salience value is computed for each visible simplified building in respective index. The salience of the visible building is calculated based on the visual difference of the original and generalized models. We propose and evaluate three methods for visual salience: local difference, global difference and minimum projection area. The real-time visualization process starts by mapping the observer to its closest indexes. Then the street view is generated based on the building information stored in theindexes. A user study shows that the local visual salience gives better result than the global and area, and the proposed method can reduce the number of loaded building by 90% while still preserve the visual similarity with the original models.

  • 191.
    Mazuelas Benito, Pablo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Fernández Torralbo, Ana
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Landsat and MODIS Images for Burned Areas Mapping in Galicia, Spain2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The extent, frequency and intensity of forest fires in Mediterranean regions have become an important problem in recent decades. Nowadays, remote sensing is an essential tool for the planning and management of the land at different scales. In the field of forest fires remote sensing images have been used in many different types of studies and currently applied to detect burned areas by means of images, providing quickly, easily and affordable the limits of burned areas immediately during or after the fire season. The importance of these products lies in the possibility to obtain perimeter, area and damage level caused by wildfires.

    The objective of this study was the evaluation of multi-scale remotely sensed images and various mapping methods for the identification and estimation of burned areas. The area of the study was situated in Galicia, a region of Spain punished year after year by important wildfires. By employing 7 images before, during and after the occurrence of forest fires, and working with different methods it was possible the collection of several products and results.

    The satellite imagery used was Landsat TM5 and MODIS, and the methods carried out were mainly spectral indices such as Normalized Burnt Ratio (NBR), Short Wave InfraRed Index (SWIR), Burnt Area Index (BAI), Burnt Area Index for MODIS (BAIM) and supervised classifications. Based on a wide literature review there were selected as suitable techniques for assess, localize and quantify burned areas. The work was separated in two sections, being differenced monotemporal and multitemporal analyses, depending on the images involved in each part.

    The results showed that which indices can distinguish burned areas with the high precision. There were found common problems of all indices as the classification of burned areas in shaded regions as unburned areas. Landsat images proved to be the most accurate images to perform studies with burned areas due to its high spatial resolution comparing with MODIS images.

    As a final products were obtained with precision the total burned area, the perimeter, the localization and the burn severity of the regions affected by wildfires. The data obtained could be used to create a database of burned areas, or based in the repetitive patterns, as useful information in order to prevent future forest fires.

  • 192. Mill, Tarvo
    et al.
    Ellmann, Artu
    Aavik, Andrus
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Sillamaee, Sven
    Determining Ranges and Spatial Distribution of Road Frost Heave by Terrestrial Laser Scanning2014In: Baltic Journal of Road and Bridge Engineering, ISSN 1822-427X, E-ISSN 1822-4288, Vol. 9, no 3, p. 225-234Article in journal (Refereed)
    Abstract [en]

    The technology of terrestrial laser scanning has evolved rapidly in recent years and it has been used in various applications, including monitoring vertical and horizontal displacements of constructions but significantly less in road frost heave assessment. Frost heave is categorised as one of the main causes of pavement surface damage in seasonal frost regions. Frost heave occurs in wintertime and in early spring at the freezing process of the ground supported structures such as roads. The major change in the structure is the increase of soil volume due to freezing of its water content. This contribution assesses vertical displacements caused by frost heave on a road using novel terrestrial laser scanning technology. The study emphasises on benefits using the technology in determining accurate magnitudes and spatial distribution of frost heave of roads. The results of case study revealed uneven spatial distribution of frost heave, which may also be an evidence of relatively poor road design quality. Therefore it is also advisable using terrestrial laser scanning in applications such as quality assessment of existing roads and in the pre-reconstruction design stage for detecting any frost heave sensitive areas in existing embankments.

  • 193.
    Mokhtary, Mandana
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Sensor Observation Service for Environmental Monitoring Data2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish Environmental Protection Agency (Naturvårdsverket) is the public agency in Sweden with responsibility to overview the conditions of the environment and the policies related to the environmental monitoring data. Nowadays, observation data are stored in several different data models in this organization, leading to difficulties in finding, understanding and consequently using data in terms of analysis and management of environmental issues. One common model that uniformly structures observation data could largely make it easier for decision makers to find the required information. The aim of this study is to build an interoperable data model for environmental monitoring observation in Naturvårdsverket based on OGC-SWE standard formats. The proposed solution relies on Sensor Web architecture, which is the set of data model definitions andweb service specifications. Also, this methodology is based on open source components; therefore it is cost-effective for the users. The Service Oriented Architecture (SOA) is used to create a uniform model by using communication protocols such as Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP). The primary findings of the thesis is that when the observation is encoded into the standard format from the beginning, then it is easier to parse these documents and find the required information for the end users without knowing how these information are gathered and stored. The client scan send a request to the Sensor Observation Service (SOS) and receive the observation that is structured based on Observation and Measurements (O&M).

  • 194.
    Mörtberg, Ulla
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Zetterberg, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Franklin, Joel
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Jonsson, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Deal, Brian
    University of Illinois at Urbana-Champaign.
    Urban ecosystems and sustainable urban development-analysing and assessing interacting systems in the Stockholm region2013In: Urban Ecosystems, ISSN 1083-8155, E-ISSN 1573-1642, Vol. 16, no 4, p. 763-782Article in journal (Refereed)
    Abstract [en]

    In order to build competence for sustainability analysis and assessment of urban systems, it is seen as essential to build on models representing urban form, landuse and transportation, urban metabolism, as well as ecological processes. This type of analysis of interacting sub-systems requires an advanced model integration platform, yet open for learning and for further development. Moreover, since the aim is to increase urban experience with ecosystem management in the wide sense, the platform needs to be open and easily available, with high visualisation capacity. For this purpose, the LEAM model was applied to the Stockholm Region and two potential future scenarios were developed, resulting from alternative policies. The scenarios differed widely and the dense urban development of Scenario Compact could be visualised, destroying much of the Greenstructure of Stockholm, while Scenario Urban Nature steered the development more to outer suburbs and some sprawl. For demonstration of the need for further development of biodiversity assessment models, a network model tied to a prioritised ecological profile was applied and altered by the scenarios. It could be shown that the Greenstructure did not support this profile very well. Thus, there is a need for dynamic models for negotiations, finding alternative solutions and interacting with other models. The LEAM Stockholm case study is planned to be further developed, to interact with more advanced transport and land use models, as well as analysing energy systems and urban water issues. This will enable integrated sustainability analysis and assessment of complex urban systems, for integration in the planning process in Stockholm as well as for comparative sustainability studies between different cities, with the goal to build more sustainable urban systems and to increase urban experiences in ecosystem management.

  • 195.
    Ngo, Duc Khanh
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Relief Planning Management Systems - Investigation of the Geospatial Components2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 196.
    Niu, Xin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Multitemporal Spaceborne Polarimetric SAR Data for Urban Land Cover Mapping2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Urban land cover mapping represents one of the most important remote sensing applications in the context of rapid global urbanization. In recent years, high resolution spaceborne Polarimetric Synthetic Aperture Radar (PolSAR) has been increasingly used for urban land cover/land-use mapping, since more information could be obtained in multiple polarizations and the collection of such data is less influenced by solar illumination and weather conditions. 

    The overall objective of this research is to develop effective methods to extract accurate and detailed urban land cover information from spaceborne PolSAR data. Six RADARSAT-2 fine-beam polarimetric SAR and three RADARSAT-2 ultra-fine beam SAR images were used. These data were acquired from June to September 2008 over the north urban-rural fringe of the Greater Toronto Area, Canada. The major landuse/land-cover classes in this area include high-density residential areas, low-density residential areas, industrial and commercial areas, construction sites, roads, streets, parks, golf courses, forests, pasture, water and two types of agricultural crops.

    In this research, various polarimetric SAR parameters were evaluated for urban land cover mapping. They include the parameters from Pauli, Freeman and Cloude-Pottier decompositions, coherency matrix, intensities of each polarization and their logarithms.  Both object-based and pixel-based classification approaches were investigated. Through an object-based Support Vector Machine (SVM) and a rule-based approach, efficiencies of various PolSAR features and the multitemporal data combinations were evaluated. For the pixel-based approach, a contextual Stochastic Expectation-Maximization (SEM) algorithm was proposed. With an adaptive Markov Random Field (MRF) and a modified Multiscale Pappas Adaptive Clustering (MPAC), contextual information was explored to improve the mapping results. To take full advantages of alternative PolSAR distribution models, a rule-based model selection approach was put forward in comparison with a dictionary-based approach.  Moreover, the capability of multitemporal fine-beam PolSAR data was compared with multitemporal ultra-fine beam C-HH SAR data. Texture analysis and a rule-based approach which explores the object features and the spatial relationships were applied for further improvement.

    Using the proposed approaches, detailed urban land-cover classes and finer urban structures could be mapped with high accuracy in contrast to most of the previous studies which have only focused on the extraction of urban extent or the mapping of very few urban classes. It is also one of the first comparisons of various PolSAR parameters for detailed urban mapping using an object-based approach. Unlike other multitemporal studies, the significance of complementary information from both ascending and descending SAR data and the temporal relationships in the data were the focus in the multitemporal analysis. Further, the proposed novel contextual analyses could effectively improve the pixel-based classification accuracy and present homogenous results with preserved shape details avoiding over-averaging. The proposed contextual SEM algorithm, which is one of the first to combine the adaptive MRF and the modified MPAC, was able to mitigate the degenerative problem in the traditional EM algorithms with fast convergence speed when dealing with many classes. This contextual SEM outperformed the contextual SVM in certain situations with regard to both accuracy and computation time. By using such a contextual algorithm, the common PolSAR data distribution models namely Wishart, G0p, Kp and KummerU were compared for detailed urban mapping in terms of both mapping accuracy and time efficiency. In the comparisons, G0p, Kp and KummerU demonstrated better performances with higher overall accuracies than Wishart. Nevertheless, the advantages of Wishart and the other models could also be effectively integrated by the proposed rule-based adaptive model selection, while limited improvement could be observed by the dictionary-based selection, which has been applied in previous studies. The use of polarimetric SAR data for identifying various urban classes was then compared with the ultra-fine-beam C-HH SAR data. The grey level co-occurrence matrix textures generated from the ultra-fine-beam C-HH SAR data were found to be more efficient than the corresponding PolSAR textures for identifying urban areas from rural areas. An object-based and pixel-based fusion approach that uses ultra-fine-beam C-HH SAR texture data with PolSAR data was developed. In contrast to many other fusion approaches that have explored pixel-based classification results to improve object-based classifications, the proposed rule-based fusion approach using the object features and contextual information was able to extract several low backscatter classes such as roads, streets and parks with reasonable accuracy.

  • 197.
    Niu, Xin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Multitemporal Spaceborne Polarimetric SAR Data for Urban Land Cover Mapping2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Urban represents one of the most dynamic areas in the global change context. To support rational policies for sustainable urban development, remote sensing technologies such as Synthetic Aperture Radar (SAR) enjoy increasing popularity for collecting up-to-date and reliable information such as urban land cover/land-use. With the launch of advanced spaceborne SAR sensors such as RADARSAT-2, multitemporal fully polarimetric SAR data in high-resolution become increasingly available. Therefore, development of new methodologies to analyze such data for detailed and accurate urban mapping is in demand.

     

    This research investigated multitemporal fine resolution spaceborne polarimetric SAR (PolSAR) data for detailed urban land cover mapping. To this end, the north and northwest parts of the Greater Toronto Area (GTA), Ontario, Canada were selected as the study area. Six-date C-band RADARSAT-2 fine-beam full polarimetric SAR data were acquired during June to September in 2008. Detailed urban land covers and various natural classes were focused in this study.

     

    Both object-based and pixel-based classification schemes were investigated for detailed urban land cover mapping. For the object-based approaches, Support Vector Machine (SVM) and rule-based classification method were combined to evaluate the classification capacities of various polarimetric features. Classification efficiencies of various multitemporal data combination forms were assessed. For the pixel-based approach, a temporal-spatial Stochastic Expectation-Maximization (SEM) algorithm was proposed. With an adaptive Markov Random Field (MRF) analysis and multitemporal mixture models, contextual information was explored in the classification process. Moreover, the fitness of alternative data distribution assumptions of multi-look PolSAR data were compared for detailed urban mapping by this algorithm.

     

    Both the object-based and pixel-based classifications could produce the finer urban structures with high accuracy. The superiority of SVM was demonstrated by comparison with the Nearest Neighbor (NN) classifier in object-based cases. Efficient polarimetric parameters such as Pauli parameters and processing approaches such as logarithmically scaling of the data were found to be useful to improve the classification results. Combination of both the ascending and descending data with appropriate temporal span are suitable for urban land cover mapping. The SEM algorithm could preserve the detailed urban features with high classification accuracy while simultaneously overcoming the speckles. Additionally the fitness of the G0p and Kp distribution assumptions were demonstrated better than the Wishart one.

  • 198.
    Niu, Xin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A Novel Contextual Classification Algorithm for Multitemporal Polarimetric SAR Data2014In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 11, no 3, p. 681-685Article in journal (Refereed)
    Abstract [en]

    This letter presents a pixel-based contextual classification algorithm by integrating a multiscale modified Pappas adaptive clustering (mMPAC) and an adaptive Markov random field (AMRF) into the stochastic expectation-maximization process for urban land cover mapping using multitemporal polarimetric synthetic aperture radar (PolSAR) data. This algorithm can effectively explore spatiotemporal contextual information to improve classification accuracy. Using the mMPAC, the problem caused by the class feature variation could be mitigated. Using the AMRF, shape details could be preserved from overaveraging that often occurs in many nonadaptive contextual approaches. Six-date RADARSAT-2 PolSAR data over the Greater Toronto Area were used for evaluation. The results show that this algorithm outperformed the support vector machine in producing homogeneous and detailed land cover classification in a complex urban environment with high accuracy.

  • 199.
    Niu, Xin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A semisupervised contextual classification algorithm for multitemporal polarimetric SAR data2012In: Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International, IEEE , 2012, p. 1777-1780Conference paper (Refereed)
    Abstract [en]

    This paper presents a contextual classification algorithm which employs the multiscale modified Pappas adaptive clustering (MPAC) approach and the Semisupervised Expectation-Maximization (SEM) procedure for urban land cover mapping using multitemporal polarimetric SAR (PolSAR) data. The proposed pixel-based algorithm explores spatio-temporal contextual information and thus could effectively improve the classification accuracy while simultaneously avoids the pepper-salt results which often occurs on the SAR images. Moreover, owing to the multiscale analysis, MPAC could adaptively preserve the detailed features comparing with other non-adaptive contextual methods. The proposed algorithm is computationally efficient and requires less parameter to be estimated. Properties of the proposed algorithm including the MRF impact, multiscale efficiency, computational performance and the initialization influence were investigated. Six-date RADARSAT-2 polarimetric SAR data over the Greater Toronto Area were used for validation. The results show that this algorithm could generate homogenous and detailed mapping results with fair accuracy for complex urban land cover classification.

  • 200.
    Niu, Xin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    An Adaptive Contextual SEM Algorithm for Urban Land Cover Mapping Using Multitemporal High-Resolution Polarimetric SAR Data2012In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 5, no 4, p. 1129-1139Article in journal (Refereed)
    Abstract [en]

    This paper presents a semi-supervised Stochastic Expectation-Maximization (SEM) algorithm for detailed urban land cover mapping using multitemporal high-resolution polarimetric SAR (PolSAR) data. By applying an adaptive Markov Random Field (MRF) with the spatially variant Finite Mixture Model (SVFMM), spatial-temporal contextual information could be effectively explored to improve the mapping accuracy with homogenous results and preserved shape details. Further, a learning control scheme was proposed to ensure a robust semi-supervised mapping process thus avoiding the undesired class merges. Four-date RADARSAT-2 polarimetric SAR data over the Greater Toronto Area were used to evaluate the proposed method. Common PolSAR distribution models such as Wishart, G0p, Kp and KummerU were compared through this contextual SEM algorithm for detailed urban land cover mapping. Comparisons with Support Vector Machine (SVM) were also conducted to assess the potential of our parametric approach. The results show that the Kp, G0p and KummerU models could generate better urban land cover mapping results than the Wishart model and SVM.

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