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  • 101.
    Furberg, Dorothy
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Satellie Monitoring of Urban Growth and Indicator-based Assessment of Environmental Impact2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    One of the major consequences of urbanization is the transformation of land surfaces from rural/natural environments to built-up land that supports diverse forms of human activity. These transformations impact the local geology, climate, hydrology, flora and fauna and human-life supporting ecosystem services in the region. Mapping and analysis of land use/land cover change in urban regions and tracking their environmental impact is therefore of vital importance for evaluating policy options for future growth and promoting sustainable urban development.

    The overall objective of this research is to investigate the extent of urban growth and/or sprawl and its potential environmental impact in the regions surrounding a few selected major cities in North America, Europe and Asia using landscape metrics and other environmental indicators to assess the landscape changes. The urban regions examined are the Greater Toronto Area (GTA) in Canada, Stockholm region and County in Sweden and Shanghai in China. The analyses are based on classificatons of optical satellite imagery (Landsat TM/ETM+ or SPOT 1/5) between 1985 and 2010. Maximum likelihood classification (MLC) under urban/rural masks, objectbased image analysis (OBIA) with rule-based classification and support vector machines (SVM) classification methods were used with grey level cooccurrence matrix (GLCM) texture features as input to help obtain higher accuracies. Based on the classification results, landscape metrics, selected environmental indicators and indices, and ecosystem service valuation were calculated and used to estimate environmental impact of urban growth.

    The results show that urban areas in the GTA grew by nearly 40% between 1985 and 2005. Results from the landscape metrics and urban compactness indicators show that low-density built-up areas increased significantly in the GTA between 1985 and 2005, mainly at the expense of agricultural areas. The majority of environmentally significant areas were increasingly surrounded by urban areas between 1985 and 2005, furthering their isolation from other natural areas. Urban areas in the Stockholm region increased by 10% between 1986 and 2006. The landscape metrics indicated that natural areas became more isolated or shrank whereas new small urban patches came into being. The most noticeable changes in terms of environmental impact and urban expansion were in the east and north of the study area. Large forested areas in the northeast dropped the most in terms of environmental impact ranking, while the most improved analysis units were close to the central Stockholm area. The study comparing Shanghai and Stockholm County revealed that urban areas increased ten times as much in Shanghai as they did in Stockholm, at 120% and 12% respectively. The landscape metrics results show that fragmentation in both study regions occurred mainly due to the growth of high density built-up areas in previously more natural environments, while the expansion of low density built-up areas was for the most part in conjunction with pre-existing patches. The growth in urban areas resulted in ecosystem service value losses of approximately 445 million USD in Shanghai, mostly due to the decrease in natural coastal wetlands, while in Stockholm the value of ecosystem services changed very little.

    This study demonstrates the utility of urban and environmental indicators derived from remote sensing data via GIS techniques in assessing both the spatio-temporal dynamics of urban growth and its environmental impact in different metropolitan regions. High accuracy classifications of optical medium resolution remote sensing data are achieved thanks in part to the incorporation of texture features for both object- and pixel-based classification methods, and to the use of urban/rural masks with the latter. The landscape metrics calculated based on the classifications are useful in quantifying urban growth trends and potential environmental impact as well as facilitating their comparison. The environmental indicator results highlight the challenges in terms of sustainable urban growth unique to each landscape, both spatially and temporally. The next phase of this PhD research will involve finding valid methods of comparing and contrasting urban growth patterns and estimated environmental impact in different regions of the world and further exploration of how to link urbanizing landscapes to changes in ecosystem services via environmental indicators.

  • 102.
    Furberg, Dorothy
    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.
    Satellite Monitoring of Urban Land Cover Change in Stockholm Between 1986 and 2006 and Indicator-Based Environmental Assessment2013In: Earth Observation of Global Changes (EOGC), Springer Berlin/Heidelberg, 2013, p. 205-222Chapter in book (Refereed)
    Abstract [en]

    Over the past few decades, there has been substantial urban growth in Stockholm, Sweden, now the largest city in Scandinavia. This research investigates and evaluates the evolution of land cover/use change in Stockholm between 1986 and 2006 with a particular focus on what impact urban growth has had on the environment using indicators derived from remote sensing and environmental data. Four scenes of SPOT imagery over the Stockholm County area were acquired for this study including two on 13 June 1986, one on 5 August 2006 and one on 4 June 2008. These images are classified into seven land cover categories using an object-based and rule-based approach with spectral data and texture measures as inputs. The classification is then used to generate spatial metrics and environmental indicators for evaluation of fragmentation and land cover/land use change. Based on the environmental indicators, an environmental impact index is constructed for both 1986 and 2006 and then compared. The environmental impact index is based on the proportion and condition of green areas important for ecosystem services, proximity of these areas to intense urban land use, proportion of urban areas in their immediate vicinity, and how impacted they are by noise. The analysis units are then ranked according to their indicator values and an average of the indicator rankings gives an overall index score. Results include a ranking of the landscape in terms of environmental impact in 1986 and 2006, as well as an analysis of which units have improved the least or the most and why. The highest ranked units are located most often to the north and east of the central Stockholm area, while the lowest tend to be located closer to the center itself. Yet units near the center also tended to improve the most in ranking over the two decades, which would suggest a convergence towards modest urban expansion and limited environmental impact.

  • 103.
    Furberg, Dorothy
    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.
    Satellite Monitoring of Urban Sprawl and Assessment of its Potential Environmental Impact in the Greater Toronto Area Between 1985 and 20052012In: Environmental Management, ISSN 0364-152X, E-ISSN 1432-1009, Vol. 50, no 6, p. 1068-1088Article in journal (Refereed)
    Abstract [en]

    This research investigates urban sprawl in the Greater Toronto Area (GTA) between 1985 and 2005 and the nature of the resulting landscape fragmentation, particularly with regard to the Oak Ridges Moraine (ORM), an ecologically important area for the region. Six scenes of Landsat TM imagery were acquired in summer of 1985, 1995, and 2005. These images and their texture measures were classified into eight land cover classes with very satisfactory final overall accuracies (93-95 %). Analysis of the classifications indicated that urban areas grew by 20 % between 1985 and 1995 and by 15 % between 1995 and 2005. Landscape fragmentation due to spatio-temporal land cover changes was evaluated using urban compactness indicators and landscape metrics, and results from the latter were used to draw conclusions about probable environmental impact. The indicator results showed that urban proportions increased in nearly all areas outside of the metropolitan center, including on portions of the ORM. The landscape metrics reveal that low density urban areas increased significantly in the GTA between 1985 and 2005, mainly at the expense of agricultural land. The metric results indicate increased vulnerability and exposure to adverse effects for natural and semi-natural land cover through greater contrast and lowered connectivity. The degree of urban perimeter increased around most environmentally significant areas in the region. Changes like these negatively impact species and the regional water supply in the GTA. Further investigation into specific environmental impacts of urban expansion in the region and which areas on the ORM are most at risk is recommended.

  • 104.
    Gao, Liang
    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.
    Multitemporal RADARSAT-2 Polarimetric SAR Data for Urban Land-Cover Mapping2010In: Proceedings of SPIE - The International Society for Optical Engineering, Bellingham: SPIE-INT SOC OPTICAL ENGINEERING , 2010, Vol. 7841Conference paper (Refereed)
    Abstract [en]

    The objective of this research is to evaluate the performance of multitemporal RADARSAT-2 polarimetric SAR data for urban land use/land-cover classification. Three dates of RADARSAT-2 polarimetric SAR data were acquired during the summer of 2008 over the rural-urban fringe of the Greater Toronto Area. The major land-cover types are residential areas, industry areas, bare land, golf courses, forest, and agricultural crops. The methodology used in this study follow the manner that first extracting the features and then carrying out the supervised classification taking the different feature combinations as an input. Support vectors machine is selected to be the classifier. SAR features including amplitude, intensity, long-term coherence, Freeman-Durden decomposition are extracted and compared by evaluating the classification abilities. Long-term coherence plays an important role in building discrimination in this study. The best classification results achieved by using the three dates HH, VH, HV amplitude layers and the coherence map. The overall accuracy is 82.3%. The results indicate that RADARSAT-2 polarimetric data has a potential to urban land-cover classification with the proper feature combinations.

  • 105.
    Gidofalvi, Gyözö
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    A Mobile Consumer Analysis Platform2010In: Proceedings of the Workshop on Innovation in Movement Behaviour Analysis: 7th International Conference on Methods and Techniques in Behavioral Research, August 24 - 27, 2010, Eindhoven, Netherlands, 2010, p. 2-Conference paper (Other academic)
    Abstract [en]

    Advances in mobile communication, computing and positioning technologies allow the real–time acquisition of continuously evolving locations of moving objects, e.g., users carrying location-aware mobile devices. This short paper proposes the geo-contextual analysis and data mining of these location traces to deliver deep insight into consumer behavior and enable a number of promising Business Intelligence services.

  • 106.
    Gidofalvi, Gyözö
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Scalable Selective Traffic Congestion Notification2015Conference paper (Refereed)
    Abstract [en]

    Congestion is a major problem in most metropolitan areas. Systems that can in a timely manner inform drivers about relevant, current or predicted traffic congestion are paramount for effective traffic management. Without loss of generality, this paper proposes such a system that by adopting a grid-based discretization of space, can flexibly scale the computation cost and the geographic level of detail of traffic information that it provides. From the continuous stream of grid-based position and speed reports from vehicles, the system incrementally derives 1) statistics for detecting directional traffic congestions and 2) model parameters for a time-inhomogeneous, Markov jump process that is used to predict the likelihood that a given vehicle will encounter a detected directional congestion within the notification horizon. A simple but efficient SQL-based prototype implementation of the system that can naturally be ported to Big Data processing frameworks is also explained in detail. Empirical evaluations on millions of object trajectories show that 1) the proposed movement model captures the topology of the underlying road network space and the directional aspects of movement on it, 2) the congestion notification accuracy of the system is superior to a linear movement model based system, and 3) the prototype implementation of the system (i) scales linearly with its input load, notification horizon and spatio-temporal resolution and (ii) can in real-time process 1.14 million object trajectories.

  • 107.
    Gidofalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ehsan, Saqib
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Developing a Benchmark for Using Trajectories of Moving Objects in Traffic Prediction and Management2010Conference paper (Other academic)
  • 108.
    Gidofalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ehsan, Saqib
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    From Trajectories of Moving Objects to Route-Based Traffic Prediction and Management2010In: Proceedings of the Workshop on Movement Pattern Analysis 2010, Zurich, Switzerland, September 14, 2010. / [ed] Björn Gottfried and Patrick Laube and Alexander Klippel andNico Van de Weghe and Roland Billen, CEUR , 2010, p. 132-135Conference paper (Refereed)
  • 109.
    Gidofalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ehsan, Saqib
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Using Trajectories of Moving Objects in Traffic Prediction and Management2010Conference paper (Refereed)
  • 110.
    Gidofalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Kaul, Manohar
    Aarhus University, Department of Computer Science.
    Borgelt, Christian
    European Centre for Soft Computing, Intelligent Data Analysis and Graphical Models Research Unit.
    Pedersen, Torben Bach
    Aalborg University, Department of Computer Science.
    Frequent route based continuous moving object location- and density prediction on road networks2011In: GIS '11 Proceedings of the 19th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems / [ed] Isabel F. Cruz and Divyakant Agrawal and Christian S. Jensen and Eyal Ofek and Egemen Tanin, ACM Press, 2011, p. 381-384Conference paper (Refereed)
    Abstract [en]

    Emerging trends in urban mobility have accelerated the need for effective traffic prediction and management systems. The present paper proposes a novel approach to using continuously streaming moving object trajectories for traffic prediction and management. The approach continuously performs three functions for streams of moving object positions in road networks: 1) management of current evolving trajectories, 2) incremental mining of closed frequent routes, and 3) prediction of near-future locations and densities based on 1) and 2). The approach is empirically evaluated on a large real-world data set of moving object trajectories, originating from a fleet of taxis, illustrating that detailed closed frequent routes can be efficiently discovered and used for prediction.

  • 111.
    Gidofalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Moran, Carlos
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Estimating Traffic Performance in Road Networks from Anonymized GPS Vehicle Probes2010In: Proceedings of the Workshop on Movement Research: Are you in the flow?: The 13th AGILE International Conference on Geographic Information Science, 10-14 May 2010, Guimarães, Portugal, 2010, p. 2-Conference paper (Other academic)
  • 112.
    Gidófalvi, Gyözö
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Fang, Dong
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    When And Where Next: Individual Mobility Prediction2012Conference paper (Refereed)
    Abstract [en]

    The ability to predict when an individual mobile user will leave his current location and where we will move next enables a myriad of qualitatively different Location-Based Services (LBSes) and applications. To this extent, the present paper proposes a statistical method that explicitly performs these related temporal and spatial prediction tasks in three continuous, sequential phases. In the First phase, the method continuously extracts grid-based staytime statistics from the GPS coordinate stream of the location-aware mobile device of the user. In the second phase, from the grid-based staytime statistics, the method periodically extracts and manages regions that the user frequently visits. Finally, in the third phase, from the stream of region-visits, the method continuously estimates parameters for an inhomogeneous continuous-time Markov model and in a continuous fashion predicts when the user will leave his current region and where he will move next. Empirical evaluations, using a number of long, real world trajectories from the Geo-Life data set, show that the proposed method outperforms a state-of-the-art, rule-based trajectory predictor both in terms of temporal and spatial prediction accuracy.

  • 113.
    Gustafsson, Klas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Berg, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Den praktiska användningen av realtidsuppdaterad fri station2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag kan det vara svårt att genomföra geodetiska mätningar med en fri station som sedan ska kunna refereras till ett känt geodetiskt referenssystem. Det pågår en ständig utveckling att ta fram nya metoder som kan lösa de problem som påverkar denna process.

    En möjlig framtida lösning kan vara realtidsuppdaterad fri station, förkortat Rufris. Rufris är en relativt ny metod för mätning som kräver tillgång till satellitsignaler men dock ingen tillgång till kända markerade punkter. Detta kan vara användbart i områden där stompunkter saknas eller där sådana antingen är gamla, icke tillförlitliga eller svårtillgängliga.

    Syftet med denna studie är att testa Rufris praktiska användbarhet och utvärdera dess prestanda i olika typer av miljöer för att ge underlag för framtida bruk av metoden. Testen genomfördes på tre olika platser på Kungliga Tekniska Högskolans(KTH) Campus i Stockholm under april 2014.

    Resultatet från studien visar att mätningarna från de flesta Rufris-etableringar avviker signifikant mot mätningar genomförda med statiska GNSS mätningar. Dock är standardosäkerheterna i stationsetableringarna och de statiska mätningarna på millimeternivåer i de flesta fall.

    Felkällor finns det flera av och dessa påverkar resultatet. Dock innebär dessa inte bara något negativt då det finns anledning att tro att felkällor av denna typ, mycket väl kan inträffa när mätningar görs med Rufris även i kommersiellt bruk.

    Studien ledde oss till slutsatserna att Rufris är en väldigt lätthanterlig metod. Det krävs bara en person för att genomföra mätningarna. En handdator och GNSS mottagare går utmärkt att bära på själv. Dock är noggrannheten i mätningarna på platser där Rufris inte etablerats med en punkt längre ifrån de övriga etableringspunkterna, inte lika hög som när en sådan punkt används. Detta stämmer överens med de teorier som finns angående mätningar med Rufris.

  • 114.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Kontinuerlig urbanisering påverkar ekosystemtjänster i Kina2012In: Kart & Bildteknik, ISSN 1651-8705, no 3, p. 26-28Article in journal (Other academic)
  • 115.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Remote Sensing of Urbanization and Environmental Impacts2013Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The unprecedented growth of urban areas all over the globe is nowadays maybe most apparent in China having undergone rapid urbanization since the late 1970s. The need for new residential, commercial and industrial areas leads to new urban regions challenging sustainable development and the maintenance and creation of a high living standard as well as the preservation of ecological functionality. Therefore, timely and reliable information on land-cover changes and their consequent environmental impacts are needed to support sustainable urban development.The objective of this research is the analysis of land-cover changes, especially the development of urban areas in terms of speed, magnitude and resulting implications for the natural and rural environment using satellite imagery and the quantification of environmental impacts with the concepts of ecosystem services and landscape metrics. The study areas are the cities of Shanghai and Stockholm and the three highly-urbanized Chinese regions Jing-Jin-Ji, the Yangtze River Delta and the Pearl River Delta. The analyses are based on classification of optical satellite imagery (Landsat TM/ETM+ and HJ-1A/B) over the past two decades. The images were first co-registered and mosaicked, whereupon GLCM texture features were generated and tasseled cap transformations performed to improve class separabilities. The mosaics were classified with a pixel-based SVM and a random forest decision tree ensemble classifier. Based on the classification results, two urbanization indices were derived that indicate both the absolute amount of urban land and the speed of urban development. The spatial composition and configuration of the landscape was analysed by landscape metrics. Environmental impacts were quantified by attributing ecosystem service values to the classifications and the observation of value changes over time.

    ivThe results from the comparative study between Shanghai and Stockholm show a decrease in all natural land-cover classes and agricultural areas, whereas urban areas increased by approximately 120% in Shanghai, nearly ten times as much as in Stockholm where no significant land-cover changes other than a 12% urban expansion could be observed. From the landscape metrics analysis results, it appears that fragmentation in both study regions occurred mainly due to the growth of high density built-up areas in previously more natural environments, while the expansion of low density built-up areas was for the most part in conjunction with pre-existing patches. Urban growth resulted in ecosystem service value losses of ca. 445 million US dollars in Shanghai, mostly due to a decrease in natural coastal wetlands. In Stockholm, a 4 million US dollar increase in ecosystem service values could be observed that can be explained by the maintenance and development of urban green spaces. Total urban growth in Shanghai was 1,768 km2 compared to 100 km2 in Stockholm. Regarding the comparative study of urbanization in the three Chinese regions, a total increase in urban land of about 28,000 km2 could be detected with a simultaneous decrease in ecosystem service values corresponding to ca. 18.5 billion Chinese Yuan Renminbi. The speed and relative urban growth in Jing-Jin-Ji was highest, followed by the Yangtze River Delta and the Pearl River Delta. The increase in urban land occurred predominately at the expense of cropland. Wetlands decreased due to land reclamation in all study areas. An increase in landscape complexity in terms of land-cover composition and configuration could be detected. Urban growth in Jing-Jin-Ji contributed most to the decrease in ecosystem service values, closely followed by the Yangtze River Delta and the Pearl River Delta.

  • 116.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Soil moisture modelling using TWI and satellite imagery in the Stockholm region2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Soil moisture is an important element in hydrological land-surface processes as well as land atmosphere interactions and has proven useful in numerous agronomical, climatological and meteorological studies. Since hydrological soil moisture estimates are usually point-based measurements at a specific site and time, spatial and temporal dynamics of soil moisture are difficult to capture. Soil moisture retrieval techniques in remote sensing present possibilities to overcome the abovementioned limitations by continuously providing distributed soil moisture data atdifferent scales and varying temporal resolutions. The main purpose of this study is to derive soil moisture estimates for the Stockholm region by means of two different approaches from a hydrological and a remote sensing point of view and the comparison of both methods.

    Soil moisture is both modelled with the Topographic Wetness Index (TWI) based on digital elevation data and with the Temperature‐Vegetation Dryness Index (TVDI) as a representation of land surface temperature and Normalized Difference Vegetation Index (NDVI) ratio. Correlations of both index distributions are investigated. Possible index dependencies onvegetation cover and underlying soil types are explored. Field measurements of soil moistureare related to the derived indices.

    The results indicate that according to a very low Pearson correlation coefficient of 0.023, nolinear dependency between the two indices existed. Index classification in low, medium and high value categories did not result in higher correlations. Neither index distribution is found to berelated to soil types and only the TVDI correlates alongside changes in vegetation cover distribution. In situ measured values correlate better with TVDIs, although neither index is considered to give superior results in the area due to low correlation coefficients. The decision which index to apply is dependent on available data, intent of usage and scale. The TWI surface is considered to be a more suitable soil moisture representation for analyses on smaller scaleswhereas the TVDI should prove more valuable on a larger, regional scale. The lack of correlation between the indices is attributed to the fact that they differ greatly in their underlying theories.

    However, the synthesis of hydrologic modelling and remote sensing is a promising field of research. The establishment of combined effective models for soil moisture determination over large areas requires more extensive in situ measurements and methods to fully assess the models’ capabilities, limitations and value for hydrological predictions.

  • 117.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Utbud och efterfrågan på ekosystemtjänster i kinesiska megastäder2014In: Kart & Bildteknik, ISSN 1651-792X, Vol. 4, p. 18-21Article in journal (Other (popular science, discussion, etc.))
  • 118.
    Haas, Jan
    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.
    Bidecadal urban land cover and ecosystem service changes in three highly urbanized regions2013Conference paper (Refereed)
    Abstract [en]

    In the past 20 years, China has experienced rapid urbanization as a consequence of economic reforms and population growth.  Urbanization is still proceeding at staggering speed. Therefore, the development of effective analytical methods to monitor the unprecedented growth of Chinese cities and the resulting environmental impacts are crucial for urban planning and sustainable development. The overall objective of this research is to investigate urban land cover change between 1990 and 2010 and the resulting effects upon ecosystem services by analysis of multitemporal Landsat 5 and HJ1-A/B images in three highly urbanized regions.

  • 119.
    Haas, Jan
    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.
    Remote sensing of bidecadal urbanization and its impact on ecosystem service in the yangtze river delta2013In: Proceedings of Dragon 2 Final Results & Dragon 3 Kick-Off Symposium: 25-29 June 2012, Beijing, P.R. China, ESA Communications , 2013, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The degree of urbanization and resulting effects on Ecosystem Services is investigated in the Yangtze River Delta in China within a 20 year time frame from 1990 to 2010. A Random forest classifier is used to classify the Landsat mosaic from 1990 and the HJ-1A/B mosaic dating from 2010. Urban Land Index (UI) and Urban Expansion Index (UX) are used to represent the intensity and rapidity of urbanization. Post-Classification Change Detection is then performed and Ecosystem Service value losses for the land-cover classes water, wetland, forest and cropland that transitioned to urban areas are calculated according to a valuation scheme adapted to the Chinese market. The results showed that Yangtze River Delta experienced significant urbanization during 1990 to 2010. Urban areas increased alongside a major decrease in cropland resulting in a substantial loss of 4.2 billion CNY in Ecosystem Services.

  • 120.
    Haas, Jan
    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.
    Remote Sensing of Bidecadal Urbanization and its Impacts on Ecosytstem Service in the Yangtze River Delta2013In: Proceedings of Dragon 2 Final Results & Dragon 3 Kick-Off Symposium, 2013Conference paper (Other academic)
    Abstract [en]

    The degree of urbanization and resulting effects on Ecosystem Services is investigated in the Yangtze River Delta in China within a 20 year time frame from 1990 to 2010. A Random forest classifier is used to classify the Landsat mosaic from 1990 and the HJ-1A/B mosaic dating from 2010. Urban Land Index (UI) and Urban Expansion Index (UX) are used to represent the intensity and rapidity of urbanization. Post-Classification Change Detection is then performed and Ecosystem Service value losses for the land-cover classes water, wetland, forest and cropland that transitioned to urban areas are calculated according to a valuation scheme adapted to the Chinese market. The results showed that Yangtze River Delta experienced significant urbanization during 1990 to 2010. Urban areas increased alongside a major decrease in cropland resulting in a substantial loss of 4.2 billion CNY in Ecosystem Services.

  • 121.
    Haas, Jan
    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.
    Satellite Monitoring of Urban Land Cover Changes and Assessing its Impact on Ecosystem Services in the Yangtze River Delta Between 1990 And 20102012Conference paper (Other academic)
  • 122.
    Haas, Jan
    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 growth and environmental impacts in Jing-Jin-Ji, the Yangtze, River Delta and the Pearl River Delta2014In: International Journal of Applied Earth Observation and Geoinformation, ISSN 0303-2434, Vol. 30, no 1, p. 42-55Article in journal (Refereed)
    Abstract [en]

    This study investigates land cover changes, magnitude and speed of urbanization and evaluates possible impacts on the environment by the concepts of landscape metrics and ecosystem services in China's three largest and most important urban agglomerations: Jing-Jin-Ji, the Yangtze River Delta and the Pearl River Delta. Based on the classifications of six Landsat TM and HJ-1A/B remotely sensed space-borne optical satellite image mosaics with a superior random forest decision tree ensemble classifier, a total increase in urban land of about 28,000 km(2) could be detected alongside a simultaneous decrease in natural land cover classes and cropland. Two urbanization indices describing both speed and magnitude of urbanization were derived and ecosystem services were calculated with a valuation scheme adapted to the Chinese market based on the classification results from 1990 and 2010 for the predominant land cover classes affected by urbanization: forest, cropland, wetlands, water and aquaculture. The speed and relative urban growth in Jing-Jin-Ji was highest, followed by the Yangtze River Delta and Pearl River Delta, resulting in a continuously fragmented landscape and substantial decreases in ecosystem service values of approximately 18.5 billion CNY with coastal wetlands and agriculture being the largest contributors. The results indicate both similarities and differences in urban-regional development trends implicating adverse effects on the natural and rural landscape, not only in the rural-urban fringe, but also in the cities' important hinterlands as a result of rapid urbanization in China.

  • 123.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Furberg, Dorothy
    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.
    Satellite monitoring of urbanization and environmental impacts: A comparison of Stockholm and Shanghai2015In: International Journal of Applied Earth Observation and Geoinformation, ISSN 0303-2434, Vol. 38, p. 138-149Article in journal (Refereed)
    Abstract [en]

    This study investigates urbanization and its potential environmental consequences in Shanghai andStockholm metropolitan areas over two decades. Changes in land use/land cover are estimated fromsupport vector machine classifications of Landsat mosaics with grey-level co-occurrence matrix fea-tures. Landscape metrics are used to investigate changes in landscape composition and configurationand to draw preliminary conclusions about environmental impacts. Speed and magnitude of urbaniza-tion is calculated by urbanization indices and the resulting impacts on the environment are quantified byecosystem services. Growth of urban areas and urban green spaces occurred at the expense of croplandin both regions. Alongside a decrease in natural land cover, urban areas increased by approximately 120%in Shanghai, nearly ten times as much as in Stockholm, where the most significant land cover changewas a 12% urban expansion that mostly replaced agricultural areas. From the landscape metrics results,it appears that fragmentation in both study regions occurred mainly due to the growth of high densitybuilt-up areas in previously more natural/agricultural environments, while the expansion of low densitybuilt-up areas was for the most part in conjunction with pre-existing patches. Urban growth resulted inecosystem service value losses of approximately 445 million US dollars in Shanghai, mostly due to thedecrease in natural coastal wetlands while in Stockholm the value of ecosystem services changed very lit-tle. Total urban growth in Shanghai was 1768 km2and 100 km2in Stockholm. The developed methodologyis considered a straight-forward low-cost globally applicable approach to quantitatively and qualitativelyevaluate urban growth patterns that could help to address spatial, economic and ecological questions inurban and regional planning.

  • 124.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Jacob, Alexander
    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 ecosystems mapping from spaceborne high-resolution optical data2014In: Proc. ‘Dragon 3 Mid-Term Results Symposium’, Chengdu, P.R. China 26–29 May 2014 (ESA SP-724, November 2014), 2014Conference paper (Refereed)
    Abstract [en]

    The potential of high-resolution optical satellite images for mapping of ecologically important urban space is investigated in this study. Both a GeoEye-1 and a Landsat 8 scene over central Shanghai were first segmented by two different algorithms and then classified into seven urban classes by SVM. Shadows in the pan-sharpened GeoEye-1 image were masked out and replaced by the corresponding pan-sharpened classified Landsat 8 image. Largest confusions occurred between sealed and permeable but non-vegetated surfaces, and between low-rise residential and high-rise commercial buildings. Based on the classification result, ecosystem service balances, supply and demand was modelled for each particular land cover class. Classification accuracies of 88% and 91% could be reached, indicating the suitability of the underlying data and method for this application domain. The KTH-SEG segmentation algorithm slightly outperformed the one implemented in eCognition. The highest supply of ecosystem services was found in water bodies whereas high-rise built-up areas revealed largest demands.

  • 125.
    Hansson, Anton
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Solar Cycles and the Accuracy and Precision of GNSS Measurements2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, GNSS (Global Navigation Satellite Systems) is a widely spread technology and are used in many different ways. GNSS is the collective name for American GPS, Russian Glonass and European Galileo and some other smaller navigation systems. When surveying with GNSS technology, there are many things that can affect the accuracy of the measurements. In this thesis the focus is on how these measurements are being effected by disturbances in the ionosphere. The conditions in the ionosphere are largely affected by the amount of solar activities. A guideline for the amount of solar activity is to monitoring the sunspot numbers and the solar cycle. With more radiation occurring at radio frequencies as well as in the UV-region with more sunspots. The resulting free electrons influence the GNSS signals as they propagate through the ionosphere and the ionized gases cause the phase of the GNSS signal to shift and slows down the speed of the signal.

     

    By processing data from three SWEPOS stations forming one shorter and one longer baseline, the estimated errors for the measurements are being calculated for different conditions in the ionosphere. The focus in this thesis is at the accuracy and precision of those measurements. To capture different ionospheric conditions, a few days from different parts of the solar cycle are chosen as representation for these different conditions. For each day different times of day and different length of measuring sessions are being calculated. All the calculations of the baselines are carried out in Trimble Business Center, and the results are presented in charts for each day and some key measurements are presented for the whole studied period.

     

    The result gives no clear correlation between the number of sunspots and the accuracy and precision of the GNSS measurements, and it is not possible from the result to see that a particular time of the day is better suited for executing GNSS surveying.

     

    From the studied material and the result of this thesis it is hard to see any dependency between the solar activity and the accuracy on GNSS measurements. It is not possible from the result see any connection between the length of the measuring time and the outcome of the measurement, as it is often no clear pattern stating that a longer measuring time would give better measurement.

     

    The results differ in many ways from other reports on this subject and the result are so totally different that something seems to not be right in this report. If a correlation analysis had been performed instead of just an ocular examination, it had probably given a more satisfying result of the studied material.

     

    The result of this thesis is in many ways on collision course with other similar report on this subject and therefore the results in this report can be neglected and rejected in favor of the result of this other more scientific reports.

  • 126.
    Hilding, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ilehag, Rebecca
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Visualization and Analysis of Historical OHCA Occurrences and Other Risk Factors for Improved Placement of AEDs2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When an out of hospital cardiac arrest (OHCA) occurs, time is of the utmost importance. For every minute that the arrest goes untreated, the chance of survival decreases rapidly. The most common treatment, that is also the most known, is Cardiopulmonary Resuscitation (CPR). Thanks to new technology, the defibrillator is no longer a tool only available to hospital personnel but to anyone who knows where they are located.

    The objective of this thesis is partly to visualize OHCA occurrences as well as visualize the differences in OHCA occurrences between locations and years. The thesis will analyze where the optimal locations of AEDs are based on a number of variables such as location and year, which is referred to as risk analysis. The analysis was performed by using daytime and nighttime population data from Statistics Sweden (SCB) in combination with heart disease statistics from the national patient register of Socialstyrelsen as well as socio-economic data from SCB. Along with that data, AED locations at the end of 2013 and OHCA data from 2006 up until 2013 was used in visualizations and risk analysis. In order to determine the final optimal placement through the risk analysis, a Geographical Information System (GIS) tool named Multi-Criteria Evaluation (MCE) was used. This tool enabled the weighting of the different parameters against each other, which was integral for the final result.

    In order to visualize differences, e.g. between two years, a raster was created which consisted of a density difference between the two years. This analysis method shows the spots where there is a majority of either case, e.g. if one area had a larger number of OHCA cases one year compared to previous year. Simple plots were included to show an overview of the problem e.g. where OHCA occurred between the years 2006 and 2013.

    The results implied that the recommended locations of AEDs while using daytime population data were located in commercial areas. Recommended AEDs from using the nighttime population data was located differently but was located as well as clusters in residential areas.

    A large source of error in the analysis was the prior heart disease data. The chosen method, an assignment of a percentage chance of heart disease per age group, is a rough and inexact approximation of the actual heart disease statistics. Had there been data about exactly where patients with prior heart disease live and work, the results would most likely be even better.

  • 127.
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Car collision warning system based on RTK GPS.2008In: FIG Working Week 2008 - Integrating Generations and FIG/UN-HABITAT Seminar – Improving Slum Conditions through Innovative Financing / [ed] Stig Enemark, 2008Conference paper (Refereed)
    Abstract [en]

    Many serious traffic accidents happen when a car drives over to the opposite lane. Aneffective way to prevent such accidents is to mount a barrier between opposite drivingdirections in form of cable fence. This is a quite expensive solution, which is not applicableon all roads. Therefore it is desirable to find alternative methods.One possible alternative is to use GPS, namely a RTK method (Real Time Kinematics), whichis capable to deliver sufficiently accurate position to compute if the car drives in correct laneand if the distance to the road edge is safe. The basic concept of the warning system is toplace the actual position of the car into a precise road model and to compute if the car isoutside or on its way out of the correct lane. If so, the system will warn the driver.This paper describes a prototype of such a warning system. The system was tested on 10 kmlong road section. The car performed 38 intentional manoeuvres that should trigger alarm.The evaluation of the tests was done visually, using video sequence synchronised with thegraphical output from the warning system. 32 manoeuvres were correctly alarmed by thesystem. The system issued 32 false alarms during 40 minutes driving. However, most of themhad only short duration, less than 0.2 s.

  • 128.
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Citynavigering - metoder och infrastruktur2010Conference paper (Other (popular science, discussion, etc.))
  • 129.
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Realtidsuppdaterad fristation: Kontrollerbarhetsanalys2011Report (Other academic)
  • 130.
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Realtidsuppdaterad fristation: Korrelationsanalys2011Report (Other academic)
  • 131.
    Horemuz, Milan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Anderson, Johan
    WSP.
    Analysis of the precision in free station establishment by RTK GPS2011In: Survey Review, ISSN 1752-2706, Vol. 43, no 323, p. 679-686Article in journal (Refereed)
    Abstract [en]

    The coordinates and orientation of a total station can be determined by using common points, i.e. pointssurveyed both by total station and RTK (Real Time Kinematics) GPS. In this paper we use a trial anderror method to analyse how the number and distribution of common points affects the precision of thetotal station establishment. It was found that a reasonable number of common points is 10 – 30, and thatthese should be distributed around the total station on a half circle. The radius of the half circle doesnot significantly affect precision of horizontal and vertical positions; it affects only orientationprecision. Therefore we suggest locating most of the common points close to the total station and a fewof them at longer distance.

  • 132.
    Horn, Matti
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    En analys av webbtjänster för bearbetning av GNSS-data2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 133.
    Hu, Hongtao
    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 RADARSAT-2 ultra-fine beam SAR data for urban land cover classification2012In: Canadian journal of remote sensing, ISSN 0703-8992, E-ISSN 1712-7971, Vol. 38, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    High-resolution optical satellite images have been widely used to update land cover information and monitor changes in urban areas. Several spaceborne synthetic aperture radar (SAR) systems are now providing SAR imagery with a spatial resolution comparable to high-resolution optical systems. Although SAR data is more reliably available than optical data, it takes more effort to employ high-resolution SAR imagery for urban applications owing to the difficulty in interpreting the complex content in SAR imagery over urban areas. The objective of this research was to develop effective object-based and rule-based methods for classification of high-resolution SAR imagery over urban areas. Multitemporal RADARSAT-2 ultra-fine beam C-HH SAR images with a pixel spacing of 1.56 m were acquired over the north part of the Greater Toronto Area during June to September in 2008. The SAR images were preprocessed and then segmented by means of a multiresolution segmentation algorithm. A range of spectral, geometrical, and textural features were selected and calculated for image objects. The image objects were classified based on these features using support vector machines (SVM). Compared with the nearest neighbor classifier, the object-based SVM produced much higher urban land cover classification accuracy (Kappa 0.43 vs. 0.63). The SVM classification result was then improved by developing specific rules to resolve the confusion among some classes. The final result indicated that the proposed methods could achieve a satisfactory overall accuracy (81.8%) for urban land cover classification using very high-resolution RADARSAT-2 SAR imagery.

  • 134.
    Hu, Hongtao
    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.
    Unsupervised Change Detection in Multitemporal SAR Images Over Large Urban Areas2014In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 7, no 8, p. 3248-3261Article in journal (Refereed)
    Abstract [en]

    Unsupervised change detection in multitemporal single-polarization synthetic aperture radar (SAR) images often involves thresholding of the image change indicator. If one class, which is usually the unchanged class, comprises a disproportionately large part of the scene, the image change indicator may have a unimodal histogram. Image thresholding of such a change indicator is a challenging task. In this paper, we present an automatic and effective approach to the thresholding of the log-ratio change indicator whose histogram may have one mode or more than one mode. A bimodality test is performed to determine whether the histogram of the log-ratio image is unimodal or not. If it has more than one mode, the generalized Kittler and Illingworth thresholding (GKIT) algorithm based on the generalized Gaussian model (GG-GKIT) is used to detect the optimal threshold values. If it is unimodal, the log-ratio image is divided into small regions and a multiscale region selection process is carried out to select regions which are a balanced mixture of unchanged and changed classes. The selected regions are combined to generate a new histogram. The optimal threshold value obtained from the new histogram is then used to separate unchanged pixels from changed pixels in the log-ratio image. Experimental results obtained on multitemporal SAR images of Toronto and Beijing demonstrate the effectiveness of the proposed approach.

  • 135.
    Hu, Hongtao
    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 and change detection with RADARSAT SAR data using neural network and rule-based classifiers2008In: XXI Congress of International Society for Photogrammetry and Remote Sensing (ISPRA). july, 2008. Beijing, China, 2008, p. 1549-1553Conference paper (Refereed)
  • 136.
    Hu, Hongtao
    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.
    Urban Land-use Mapping and Change Detection with RADARSAT Fine-Beam SAR Data Using Neural Network and Rule-based Classifiers2008In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Beijing 2008, 2008, p. 1549-1554Conference paper (Other academic)
    Abstract [en]

    This paper presents a new approach to extract urban landuse/land-cover information from high-resolution radar satellite data. Five-date RADARSAT fine-beam SAR images over the rural-urban fringe of the Greater Toronto Area were acquired during May to August in 2002. One scene of Landsat TM imagery was acquired in 1988 for change detection. The major landuse/land-cover classes were high-density built-up areas, low-density built-up areas, roads, forests, parks, golf courses, water and four types of agricultural crops (soybeans, corn, winter wheat/rye and pasture). The proposed approach to classify SAR images consisted of three steps: 1) image segmentation, 2) feature selection and object-based neural network classification, 3) rule set development to improve classification accuracy. Post-classification change detections were then performed using the final classification result of RADARSAT SAR images and the classification result of Landsat TM imagery. The results showed that the proposed approach achieved very good classification accuracy (overall: 87.9%; kappa: 0.867). The change detection procedure was able to identify the areas of significant changes, for example, new built-up areas, even though the overall accuracy of the change detection was not high.

  • 137.
    Hu, Hongtao
    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-landuse/land-cover mapping with high-resolution SAR imagery by integrating support vector machines into object-based analysis2008In: SPIE Europe Remote Sensing Conference, 2008, 2008, Vol. 7110Conference paper (Refereed)
    Abstract [en]

    Thispaper investigates the capability of high-resolution SAR data for urbanlanduse/land-cover mapping by integrating support vector machines (SVMs) into object-basedanalysis. Five-date RADARSAT fine-beam C-HH SAR images with a pixelspacing of 6.25 meter were acquired over the rural-urban fringeof the Great Toronto Area (GTA) during May to Augustin 2002. First, the SAR images were segmented using multi-resolutionsegmentation algorithm and two segmentation levels were created. Next, arange of spectral, shape and texture features were selected andcalculated for all image objects on both levels. The objectson the lower level then inherited features of their superobjects. In this way, the objects on the lower levelreceived detailed descriptions about their neighbours and contexts. Finally, SVMclassifiers were used to classify the image objects on thelower level based on the selected features. For training theSVM, sample image objects on the lower level were used.One-against-one approach was chosen to apply SVM to multiclass classificationof SAR images in this research. The results show thatthe proposed method can achieve a high accuracy for theclassification of high-resolution SAR images over urban areas.

  • 138.
    Hu, Yunfeng
    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.
    ALOS PolSAR Interferometry for Analysis of Wenchuan Earthquake in China2009In: Second International Conference on Earth Observation for Global Changes, SPIE - International Society for Optical Engineering, 2009Conference paper (Refereed)
  • 139.
    Hu, Yunfeng
    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.
    Zhang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Liu, Jiyuan
    The Trajectory of Urbanization Process in the Yangtze River Delta During 1990 to 20052009In: 2009 JOINT URBAN REMOTE SENSING EVENT, NEW YORK: IEEE , 2009, p. 407-414Conference paper (Refereed)
    Abstract [en]

    Rapid economic development, combined with tremendous population growth and migration from rural areas, has resulted in a dramatic urbanization in the Yangtze River Delta over the last three decades. In order to develop a more quantitative understanding of urbanization trajectory in the Yangtze Delta from the late 1980s to 2005, the time-series national land cover/land-use database (NLCD), interpreted from remote sensing imagery (including Landsat TM, ETM+ and CBERS), was examined from the aspects of spatial pattern and temporal process. The results showed that the urban land in the Yangtze River Delta has increased from 2.29x10(3) km(2) in the late 1980s to 4.19x10(3) km(2) in 2005. The percentages of total land area in the Yangtze Delta occupied by urban environments in the late 1980s, 1995, 2000 and 2005 were 2.09%, 3.03%, 3.28%, and 3.82% respectively. During the late 1980s - 2005, the total urban expansion in this region was 1.92x10(3) km(2), resulting in an annual urban expansion area (UXa) of about 118.72 km(2) per year, with an urban erpansion intensity (UXt)of 83.03%. There were significant spatial trends and differences in urbanization level and urban expansion. Most urban land and urban expansion have occurred along the Huning Railway (Shanghai-Nanjing) and the Hanzhou Bay. This study also revealed substantial temporal differences in the rate at which urban areas have expanded. There was a great deal of urban growth in the late 1980s - 1995, and also in 2000 - 2005. The 1995 - 2000 period saw a slow expansion speed due to government initiatives designed to hall the loss of agricultural land. In this study, both patterns and dynamics of urban distribution and urban expansion were examined on temporal and spatial scales, and integrated to produce a comprehensive evaluation of recent urbanization trajectory in the Yangtze River Delta.

  • 140.
    Hu, Yunfeng
    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.
    Zhang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Zhang, Xueyan
    Liu, Jiyuan
    Zhuang, Dafang
    Spatial-Temporal Pattern of GIMMS NDVI and Its Dynamics in Mongolian Plateau2008In: International Workshop on Earth Observation and Remote Sensing Applications, EORSA2008, NEW YORK: IEEE , 2008, p. 119-124Conference paper (Refereed)
    Abstract [en]

    The physical geography of Mongolian Plateau plays an important role in the East Asian climate ecology system. In this research, GIMMS NDVI, the third generation of NDVI dataset, was processed using the MVC method first, then the spatial-temporal patterns of GIMMS NDVI in Mongolian Plateau during 1982-2003 was investigated, and the transect from Tariat to Xilin Gol was also selected to analyze the NDVI dynamic processes in detail. The results demonstrated that: 1) The general spatial distribution pattern of NDVI showed a clear spatial differentiation. The high value pixels were mainly distributed in the east and north of Mongolian Plateau with forest and meadow steppe land cover, while the low value pixels were mainly distributed in the west and centre part of Mongolian Plateau with desert and Gobi land cover. However, the annual NDVI variability was relative small either in the high-covered regions (i.e. forest, forest steppe, and meadow steppe) or in low-covered regions (i.e. steppe desert, desert and Gobi), while the region with typical steppe normally had higher annual NDVI variability; 2) During 1982-2003, the dynamic evolution process of NDVI in Mongolian Plateau also showed an evident spatial differentiation. About 12.4% of total area featured a significant increase, 4.8% of total area featured an increase but without significance, and 9.3% of total area featured decrease without significance. The other part, about 73.5% of total area, had no obvious change. The NDVI increased significantly in the South-East, South and of Mongolian Plateau, while it decreased in the North-East and North of Mongolian Plateau. Further, the NDVI-increased regions were those typical steppe and farming-pastoral regions before, while the NDVI-decreased regions were those well-covered forest, forest steppe and meadow steppe regions before.

  • 141. Huang, Wei
    et al.
    Li, Songnian
    Liu, Xintao
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Predicting human mobility with activity changes2015In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 29, no 9, p. 1569-1587Article in journal (Refereed)
    Abstract [en]

    Human mobility patterns can provide valuable information in understanding the impact of human behavioral regularities in urban systems, usually with a specific focus on traffic prediction, public health or urban planning. While existing studies on human movement have placed huge emphasis on spatial location to predict where people go next, the time dimension component is usually being treated with oversimplification or even being neglected. Time dimension is crucial to understanding and detecting human activity changes, which play a negative role in prediction and thus may affect the predictive accuracy. This study aims to predict human movement from a spatio-temporal perspective by taking into account the impact of activity changes. We analyze and define changes of human activity and propose an algorithm to detect such changes, based on which a Markov chain model is used to predict human movement. The Microsoft GeoLife dataset is used to test our methodology, and the data of two selected users is used to evaluate the performance of the prediction. We compare the predictive accuracy (R-2) derived from the data with and without implementing the activity change detection. The results show that the R-2 is improved from 0.295 to 0.762 for the user with obvious activity changes and from 0.965 to 0.971 for the user without obvious activity changes. The method proposed by this study improves the accuracy in analyzing and predicting human movement and lays the foundation for related urban studies.

  • 142.
    Hulumtaye Kefyalew Yederulh, Hulumtaye
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Investigation of the use of Laser Scanning for Deformation Monitoring2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The ability of fast and accurate acquiring of large 3D spatial data is the main benefit for consideration of a terrestrial laser scanner in deformation monitoring. The objective of this paper is to discuss this technique with support of practical experiments performed inside a laboratory. It also includes measuring changes from millimetre to sub millimetre level and a comparison of measurements from a terrestrial laser scanner with measurements of other instruments. Various areas of applications are reviewed. The report discusses a surface modeling method to estimate deformation parameters of objects, such as planar, spherical and cylindrical surface representations. Illustrative numerical examples are performed by simulating randomly generated sample point coordinates for estimation of changes of modeled planar and cylindrical surfaces. The practical experiments were performed using a scan of a carton box, a ball and a rounded paper holder, which correspond to the planar, spherical and cylindrical surfaces, respectively. Independent measurements were performed using a total station and a measuring tape to make a comparison with the scanner measurements. A statistical test was performed independently for the changes obtained from each type of modeled surface in order to check whether the movement is real or due to measurement noises.  A significant change of the normal of a plane was detected between epochs, and similar results were obtained from both scanner and total station measurements. The normal of the plane was rotated by  between scan epochs. A translation of 3.2 and 3.7 millimetres were detected between scan epochs for the center of the sphere and axis of the cylinder, respectively. Only the scanner data was used in this case. From the scanner measurement changes in radii of the sphere and the cylinder were obtained as 1.6 and 3.1 millimetres, respectively between scan epochs. The measurement of the scanner was verified by performing independent measurements using measuring tape. And hence the change in radii of the sphere and the cylinder were obtained as 2.5 and 4 millimetres, respectively. 

  • 143.
    Hägglund Eriksson, Malin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Accuracy and Precision Analysis of Total Station Measurements2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main objective of this bachelor thesis was to gain awareness of accuracy and precision in total station measurements. Experiments were designed, executed and analyzed.

     

    The approach to the subject was to examine measurements made with various prism set-ups. Prisms are supposed to be directed to the total station with the front face in the line of sight. In the experiment the prisms were directed in various angles in order to measure in non-perfect measuring arrangement and the behavior of the precision and accuracy were noted.

     

    The mean values and standard uncertainties were calculated from the material as well as RMS Error in the cases where reference values could be used as true values. The reference values for comparison were available due to the possibility to use a test field – a network of concrete pillars with well-defined coordinates.

     

    To see whether the precision (the standard uncertainty) changed between a measurement sample made with correctly positioned prisms and a measurement sample towards the angled prisms, a statistical test method was used. (The test method is recommended in the international standard ISO 17123-1; Optics and optical instruments, Field procedures for testing geodetic and surveying instruments, Part 1: Theory).

     

    The results from the experiments showed that there were larger standard uncertainties in the slope distance measurements towards extreme angled prisms than to correctly directed prisms. Surprisingly it was also larger standard uncertainty in vertical angle measurements toward correctly directed prisms than slightly angled prisms. The mean values of the horizontal angle measurement drifted sideways in the measurements made towards one extreme angle to the opposite extreme so that a total shift of around one centimeter was detected at short distances as well as up to 100 m distance.

     

     When aiming in between the separate prisms of 360-degree targets the standard uncertainty were larger in horizontal angle measurements at a few occasions where it seemed like the autolock function had chosen two different prisms to lock on to, at separate occasions. The standard uncertainties were also larger in all vertical angle measurements when aiming in between the prisms.

     

    The results showed clearly that even when the standard uncertainties of the measurements were of equal size, the mean values – when measuring in the different test positions – could vary substantially.

     

  • 144.
    Inerbayeva (Shoganbekova), Daniya
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Determination of a gravimetric geoid model of Kazakhstan using the KTH-method2010Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    This study work deals with the determination of the gravimetric geoid model for Kazakhstan by using the KTH-method.

    A number of data sets were collected for this work, such as the gravity anomalies, high-resolution Digital Elevation Model (DEM), Global Geopotential Models (GGMs) and GPS/Levelling data. These data has been optimally combined through the KTH approach, developed at the Royal Institute of Technology (KTH) in Stockholm. According to this stochastic method, Stokes’ formula is being used with the original surface gravity anomaly, which combine with a GGM yields approximate geoid heights. The corrected geoid heights are then obtained by adding the topographic, downward continuation, atmospheric and ellipsoidal corrections to the approximate geoid heights.

    To compute the geoid model for Kazakhstan as accurately as possible with available data set different numerical tests have been performed:

    • Choice of the best fit geopotential model in the computation area
    • Investigations for the best choice of the initial condition for determination of the least-squares parameters
    • Selection of the best parametric model for reducing the effect of the systematic error and data inconsistencies between computed geoid heights and GPS/Levelling heights.

     Finally, 5'x5' Kazakh gravimetric geoid (KazGM2010) has been modelled. 

  • 145.
    Isaksson, Camilla
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    HTML5-based Travel HabitApplication: Investigation of VectorWeb Mapping Possibilities2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The subject of the report is to review and evaluate the potential for vector graphics in web maps. It ishoped that a web mapping only should display vector graphics. Compared to the traditional webmapping approach, that has raster tiles pre-rendered on the server side for each zoom level. Thedrawback with raster data is that it lacks in information content compared to vector data, which interms can contribute to a richer user interface. However, vector graphics, in comparison to raster datahave a complex data structure and are inefficient to handle such as raster data traditionally is managed.Thanks to new rendering techniques for vector graphics, such as by VML, SVG, but mainly throughthe canvas element, web maps can be improved since vector graphics can be drawn directly in theclient through the browser without the need to generate data on the server side and sent it to the client.By selecting three vector-based mobile mapping libraries that use HTML5, in particular the canvaselement, each library is examined and evaluated based on their ability to use vector graphics, bothperformance-wise, by randomly generating vector data on a map comprising of the world, but alsoaccording to a number of usability criteria. Thereafter, a mobile travel habit implementation isdeveloped based on one of the libraries that meets the criteria the best. The travel habit application isdesigned to register the user’s geographical movements and subsequently display the user’s completedtrip in terms of vector data on a map. The application is developed with the ASP.NET technique thatconsists of HTML, JavaScript and C# languages. Results show that each library is superior / comparesfavourably to the others for at least one of the assessment criteria. Based on the performance test forthe rendering of vector data, the Tile5 library performed best with a rendering time corresponding toapproximately half the time it took for the second best library Leaflet. However, since Tile5 indicatesdeficiencies in the documentation, Leaflet fits the overall established assessment criteria best and isselected for the implemented of the mobile application for travel habits. For future development, Tile5has the potential to become a useful and effective tool for vector web mapping and to compete withthe traditional mapping platforms that renders raster data.

  • 146.
    Ivarsson, Caroline
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Combining Street View and Aerial Images to Create Photo-Realistic 3D City Models2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis evaluates two different approaches of using panoramic street view images for creating more photo-realistic 3D city models comparing to 3D city models based on only aerial images. The thesis work has been carried out at Blom Sweden AB with the use of their software and data.

    The main purpose of this thesis work has been to investigate if street view images can aid in creating more photo-realistic 3D city models on street level through an automatic or semi-automatic approach. Two different approaches have been investigated in this thesis work: using the street view images for texturing already generated 3D building models and using the street view images directly for reconstructing 3D city models. Data was collected over the study area of KTH, Stockholm, Sweden and the models were created with the two software TerraPhoto, used for texturing, and Smart3DCapture, used for reconstruction. The created models were analyzed and compared with the models based on only aerial images and the two approaches were compared to each other.

    Through using also street view images when creating city models the models are shown to become more photo-realistic representations on street level compared to the models based on only aerial images. The two tested approaches create very different 3D city models in terms of what is visible in the final model, a textured buildings model or a fully reconstructed environment, and also contains different amount of involved manual work. The textured models contain only the buildings and tend to look very flat because the street images are being projected onto flat building walls whereas the reconstructed models reconstructs everything being visible in the images, trees, cars etc., and create a full scale 3D city model.

    There are however limitations associated with using street view images when modeling cities since they only contain information on the ground level and no information about roofs or higher parts of the city environment and the street view images therefore need to be used in combination with aerial images. Using the street view images for reconstructing city models showed some complications in terms of wavy facades, bumpy roads and objects such as trees being inaccurately modeled. The texturing approach creates less visually pleasing models since objects such as trees and lighting poles are being projected onto the facades. The models based on aerial images look more visually appealing compared to when also using the street view images but lack the resolution be considered as photo-realistic on street level. This thesis work has shown that there is potential in using street view images when creating photo-realistic 3D city models on street level even though it is not yet a semi-automatic or automatic approach.

  • 147.
    Jacob, Alexander
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Multitemporal Remote Sensing for Urban Mapping using KTH-SEG and KTH-Pavia Urban Extractor2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this licentiate thesis is to develop novel algorithms and improve existing methods for urban land cover mapping and urban extent extraction using multi-temporal remote sensing imagery. Past studies have demonstrated that synthetic aperture radar (SAR) have very good properties for the analysis of urban areas, the synergy of SAR and optical data is advantageous for various applications. The specific objectives of this research are:

    1. To develop a novel edge-aware region-growing and -merging algorithm, KTH-SEG, for effective segmentation of SAR and optical data for urban land cover mapping;

    2. To evaluate the synergistic effects of multi-temporal ENVISAT ASAR and HJ-1B multi-spectral data for urban land cover mapping;

    3. To improve the robustness of an existing method for urban extent extraction by adding effective pre- and post-processing.

    ENVISAT ASAR data and the Chinese HJ-1B multispectral , as well as TerraSAR-X data were used in this research. For objectives 1 and 2 two main study areas were chosen, Beijing and Shanghai, China. For both sites a number of multitemporal ENVISAT ASAR (30m C-band) scenes with varying image characteristics were selected during the vegetated season of 2009. For Shanghai TerraSAR-X strip-map images at 3m resolution X-band) were acquired for a similar period in 2010 to also evaluate high resolution X-band SAR for urban land cover mapping. Ten  major landcover classes were extracted including high density built-up, low density built-up, bare field, low vegetation, forest, golf course, grass, water, airport runway and major road.

    For Objective 3, eleven globally distributed study areas where chosen, Berlin, Beijing, Jakarta, Lagos, Lombardia (northern Italy), Mexico City, Mumbai, New York City, Rio de Janeiro, Stockholm and Sydney. For all cities ENVISAT ASAR imagery was acquired and for cities in or close to mountains even SRTM digital elevation data.

    The methodology of this thesis includes two major components, KTH-SEG and KTH-Pavia Urban Extractor. KTH-SEG is an edge aware region-growing and -merging algorithm that utilizes both the benefit of finding local high frequency changes as well as determining robustly homogeneous areas of a low frequency in local change. The post-segmentation classification is performed using support vector machines. KTH-SEG was evaluated using multitemporal, multi-angle, dual-polarization ASAR data and multispectral HJ-1B data as well as TerraSAR-X data. The KTH-Pavia urban extractor is a processing chain. It includes: Geometrical corrections, contrast enhancement, builtup area extraction using spatial stastistics and GLCM texture features, logical operator based fusion and DEM based mountain masking.

    For urban land cover classification using multitemporal ENVISAT ASAR data, the results showed that KTH-SEG achieved an overall accuracy of almost 80% (0.77 Kappa ) for the 10 urban land cover classes both Beijign and Shanghai, compared to eCognition results of 75% (0.71 Kappa) In particular the detection of small linear features with respect to the image resolution such as roads in 30m resolved data went well with 83% user accuracy from KTH-SEG versus 57% user accuracy using the segments derived from eCognition. The other urban classes which in particular in SAR imagery are characterized by a high degree of heterogeneity were classified superiorly by KTH-SEG. ECognition in general performed better on vegetation classes such as grass, low vegetation and forest which are usually more homogeneous.

    It is was also found that the combination of ASAR and HJ-1B optical data was beneficial, increasing the final classification accuracy by at least 10% compared to ASAR or HJ-1B data alone. The results also further confirmed that a higher diversity of SAR type images is more important for the urban classification outcome. However, this is not the case when classifying high resolution TerraSAR-X strip-map imagery. Here the different image characteristics of different look angles, and orbit orientation created more confusion mainly due to the different layover and foreshortening effects on larger buildings. The TerraSAR-X results showed also that accurate urban classification can be achieved using high resolution SAR data alone with almost 84% for  eight classes around the Shanghai international Airport (high and low density built-up were not separated as well as roads and runways).

    For urban extent extraction, the results demonstrated that built-up areas can be effectively extracted using a single ENVISAT ASAR image in 10 global cities reaching overall accuracies around 85%, compared to 75% of MODIS urban class and 73% GlobCover Urban class. Multitemporal ASAR can improve the urban extraction results by 5-10% in Beijing. Mountain masking applied in Mumbai and Rio de Janeiro increased the accuracy by 3-5%.The research performed in  this thesis has contributed to the remote sensing community by providing algorithms and methods for both extracting urban areas and identifying urban land cover in a more detailed fashion. 

  • 148.
    Jacob, Alexander
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Radar and Optical Data Fusion for Object Based Urban Land Cover Mapping2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The creation and classification of segments for object based urban land cover mapping is the key goal of this master thesis. An algorithm based on region growing and merging was developed, implemented and tested. The synergy effects of a fused data set of SAR and optical imagery were evaluated based on the classification results.

    The testing was mainly performed with data of the city of Beijing China. The dataset consists of SAR and optical data and the classified land cover/use maps were evaluated using standard methods for accuracy assessment like confusion matrices, kappa values and overall accuracy. The classification for the testing consists of 9 classes which are low density buildup, high density buildup, road, park, water, golf course, forest, agricultural crop and airport.

    The development was performed in JAVA and a suitable graphical interface for user friendly interaction was created parallel to the development of the algorithm. This was really useful during the period of extensive testing of the parameter which easily could be entered through the dialogs of the interface.

    The algorithm itself treats the pixels as a connected graph of pixels which can always merge with their direct neighbors, meaning sharing an edge with those. There are three criteria that can be used in the current state of the algorithm, a mean based spectral homogeneity measure, a variance based textural homogeneity measure and fragmentation test as a shape measure. The algorithm has 3 key parameters which are the minimum and maximum segments size as well as a homogeneity threshold measure which is based on a weighted combination of relative change due to merging two segments. The growing and merging is divided into two phases the first one is based on mutual best partner merging and the second one on the homogeneity threshold. In both phases it is possible to use all three criteria for merging in arbitrary weighting constellations. A third step is the check for the fulfillment of minimum size which can be performed prior to or after the other two steps.

    The segments can then in a supervised manner be labeled interactively using once again the graphical user interface for creating a training sample set. This training set can be used to derive a support vector machine which is based on a radial base function kernel. The optimal settings for the required parameters of this SVM training process can be found from a cross-validation grid search process which is implemented within the program as well. The SVM algorithm is based on the LibSVM java implementation. Once training is completed the SVM can be used to predict the whole dataset to get a classified land-cover map. It can be exported in form of a vector dataset.

    The results yield that the incorporation of texture features already in the segmentation is superior to spectral information alone especially when working with unfiltered SAR data. The incorporation of the suggested shape feature however doesn’t seem to be of advantage, especially when taking the much longer processing time into account, when incorporating this criterion.

    From the classification results it is also evident, that the fusion of SAR and optical data is beneficial for urban land cover mapping. Especially the distinction of urban areas and agricultural crops has been improved greatly but also the confusion between high and low density could be reduced due to the fusion.

  • 149.
    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.
    Fusion of Multitemporal Multi-Angle ENVISAT ASAR and HJ-1 Data for Object-based Urban Land Cover Classification2012In: FUSION OF MULTITEMPORAL ENVISAT ASAR AND HJ-1 DATA FOR OBJECT-BASED LAND COVER MAPPING, 2012, p. 52-57Conference paper (Other academic)
    Abstract [en]

    The key goal of this work is to analyze the synergistic effects of multitemporal data fusion for urban land cover mapping. In particular this analysis is carried out using multitemporal ENVISAT ASAR images and one Chinese HJ-1 optical image acquired over Beijing in 2009. The major land cover classes are high-density built-up areas, low-density built-up areas, roads, airports, forests, parks, golf courses, grass/pasture, crops, bare fields and water. The methodology used in this research including orthorectification, SAR speckle filtering, and object-based classification. The segmentation is based on the newly developed algorithm KTH-SEG that utilizes an edge-aware region growing and merging approach. Fusion of the various combinations of multitemporal multi-angle SAR data and HJ-1 data were compared with SAR and optical data alone. The preliminary results show that the fusion of ENVISAT ASAR and HJ-1 data performed much better than optical data alone or SAR data alone. The fusion of 4-date SAR data and optical data can achieve similar classification accuracy as the fusion of 8-date SAR data and optical data if multi-angle, dual look direction SAR data with suitable temporal compositions are selected. Compared to eCognition, the KTH-SEG performed better in extracting linear features such as roads and rivers.

  • 150.
    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.
    Segmentation of multi-temporal envisat asar and hj-1b optical data using an edge-aware region growing and merging algorithm2013In: European Space Agency, (Special Publication) ESA SP, Volume 704 SP, 2013, 2013Conference paper (Refereed)
    Abstract [en]

    The paper aims to develop image segmentation algorithms for classification of multi-sensor data in urban areas. For this purpose an algorithm called KTHSEG has been developed using an edge-aware region growing and merging algorithm. Four-date ENVISAT ASAR C-HH data and one-date HJ-1B covering the city of Shanghai acquired during the vegetation season of 2009 were selected this research. The results show that the segmentation algorithm is effective for urban land cover classification using SAR and optical data. The results also confirm that the fusion of SAR and optical data is beneficial for urban land cover mapping. Further, the study showed that the combination of one SAR and one optical scene is enough to achieve good results and the addition of multitemporal SAR data from the same beam mode does not improve classification accuracy.

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