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  • 51. Giovanidis, A.
    et al.
    Haustein, T.
    Jorswieck, Eduard
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Kim, D.
    Maximization of the single user rate in OFDMA assuming equal power on allocated subcarriers2007In: 2007 IEEE 65th Vehicular Technology Conference, IEEE , 2007, p. 2751-2755Conference paper (Refereed)
    Abstract [en]

    The problem of optimal power allocation for a single user in an OFDMA system is considered for uplink, under the assumption that the total power is divided equally to a selected subset of subcarriers. This scenario suggests reduced feedback information for power control from base station to the user since only the information over modulation on each subcarrier is necessary. Assuming knowledge of the instantaneous users' channel gains, the rate optimization problem reduces to a subcarrier allocation problem, discribed by a discrete function with the set of possible allocated subcarriers as domain and the set of achievable sum rates as range. A continuous equivalent of the function is used to derive properties that also hold in the discrete case. The function is in general not concave and concavity holds only for high CNR regions - over a specified bound. In all cases however it is proved that the maximum is unique and a simple and efficient algorithm is proposed for subcarrier allocation which always provides the optimal solution concerning the subcarriers to be loaded. The cost in achievable capacity from the use of equal-power compared to actual waterfilling is calculated, which is shown to be small while the gain in frequency resources and feedback reduction is important.

  • 52. Gutiérrez, I.
    et al.
    Bader, F.
    Pijoan, J.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Adaptive resource management for a MC-CDMA system with mixed QoS classes using a cross layer strategy2007In: 2007 IEEE 65th Vehicular Technology Conference, IEEE , 2007, p. 3036-3040Conference paper (Refereed)
    Abstract [en]

    Wireless communications are experiencing a great increasing demand, both user and bandwidth capacity. The efficiency in the resource management and usage will be a dramatically important issue since spectrum and power is a scarce resource, even more in the wireless environment. Under these circumstances, adaptive resource management will lead to high spectral efficiency rates and power saving algorithms. Previous works have focused on increasing the system capacity by means of complex power and rate adaptation techniques at the expense of unfair systems. The present proposal proposes a low complexity algorithm for adaptive resource allocation considering different quality of service classes in a Multicarrier-Code Division Multiple Access (MC-CDMA) system, which is considered according to several researches, as a promising air interface scheme for the Beyond 3G systems.

  • 53.
    Gylfason, Kristinn B.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sohlström, Hans
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Ottonello Briano, Floria
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    A Sensor Device and a Method of Detecting a Component in Gas2015Patent (Other (popular science, discussion, etc.))
  • 54. Haas, J.
    et al.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Sentinel-1A SAR and sentinel-2A MSI data fusion for urban ecosystem service mapping2017In: Remote Sensing Applications: Society and Environment, ISSN 2352-9385, Vol. 8, p. 41-53Article in journal (Refereed)
    Abstract [en]

    The two main objectives of this study are to evaluate the potential use and synergetic effects of ESA Sentinel-1A C-band SAR and Sentinel-2A MSI data for classification and mapping of ecologically important urban and peri-urban space and to introduce spatial characteristics into ecosystem service analyses based on remotely sensed data. Image resolutions between 5 m and 20 m provided by the Sentinel satellites introduce a new relevant spatial scale in-between high and medium resolution data at which not only urban areas but also their important hinterlands can be effectively and efficiently mapped. Sentinel-1/2 data fusion facilitates both the capture of ecologically relevant details while at the same time also enabling large-scale urban analyses that draw surrounding regions into consideration. The combined use of Sentinel-1A SAR in Interferometric Wide Swath mode and simulated Sentinel-2A MSI (APEX) data is being evaluated in a classification of the Zürich metropolitan area, Switzerland. The SAR image was terrain-corrected, speckle-filtered and co-registered to the simulated Sentinel-2 image. After radiometric and spatial resampling, the fused image stack was segmented and classified by SVM. After post-classification, landscape elements were investigated in terms of spatial characteristics and topological relations that are believed to influence ecosystem service supply and demand, i.e. area, contiguity, perimeter-to-area ratio and distance. Based on the classification results, ecosystem service supplies and demands accounting for spatial and topological patch characteristics were attributed to 14 land cover classes. The quantification of supply and demand values resulted in a positive ecosystem service budget for Zürich. The spatially adjusted service budgets and the original budgets are similar from a landscape perspective but deviate up to 50% on the patch level. The introduction of spatial and topological patch characteristics gives a more accurate impression of ecosystem service supply and demands and their distributions, thus enabling more detailed analyses in complex urban surroundings. The method and underlying data are considered suitable for urban land cover and ecosystem service mapping and the introduction of spatial aspects into relative ecosystem service valuation concepts is believed to add another important aspect in currently existing approaches.

  • 55.
    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)
  • 56.
    Haas, Jan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Remote Sensing of Urbanization and Environmental Impacts2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis aims to establish analytical frameworks to map urban growth patterns with spaceborne remote sensing data and to evaluate environmental impacts through Landscape Metrics and Ecosystem Services. Urbanization patterns at regional scale were evaluated in China's largest urban agglomerations and at metropolitan scale in Shanghai, Stockholm and Beijing using medium resolution optical satellite data. High-resolution data was used to investigate changes in Shanghai’s urban core. The images were co-registered and mosaicked. Tasseled Cap transformations and texture features were used to increase class separabilities prior to pixel-based Random Forest and SVM classifications. Urban land cover in Shanghai and Beijing were derived through object-based SVM classification in KTH-SEG. After post-classification refinements, urbanization indices, Ecosystem Services and Landscape Metrics were used to quantify and characterize environmental impact. Urban growth was observed in all studies. China's urban agglomerations showed most prominent urbanization trends. Stockholm’s urban extent increased only little with minor environmental implications. On a regional/metropolitan scale, urban expansion progressed predominately at the expense of agriculture. Investigating urbanization patterns at higher detail revealed trends that counteracted negative urbanization effects in Shanghai's core and Beijing's urban-rural fringe. Beijing's growth resulted in Ecosystem Services losses through landscape structural changes, i.e. service area decreases, edge contamination or fragmentation. Methodological frameworks to characterize urbanization trends at different scales based on remotely sensed data were developed. For detailed urban analyses high-resolution data are recommended whereas medium-resolution data at metropolitan/regional scales is suggested. The Ecosystem Service concept was extended with Landscape Metrics to create a more differentiated picture of urbanization effects.​

  • 57.
    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.

  • 58.
    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.))
  • 59.
    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.

  • 60.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Mapping and Moitoring Urban Ecosystem Services Using High-Resolution Satellite DataManuscript (preprint) (Other academic)
  • 61.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Mapping and Monitoring Urban Ecosystem Services Using Multitemporal High-Resolution Satellite Data2016In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 10, no 2, p. 669-680Article in journal (Refereed)
    Abstract [en]

    This study aims at providing a new method to efficiently analyse detailed urban ecological conditions at the example of Shanghai, one of the world’s most densely populated megacities. The main objective is to develop a method to effectively analyse high-resolution optical satellite data for mapping of ecologically important urban space and to evaluate ecological changes through the emerging ecosystem service supply and demand budget concept. Two IKONOS and GeoEye-1 scenes were used to determine land use/land cover change in Shanghai's urban core from 2000 to 2009. After pre-processing, the images were segmented and classified into seven distinct urban land use/land cover classes through SVM. The classes were then transformed into ecosystem service supply and demand budgets based on ecosystem functions. Decreases of continuous urban fabric and industrial areas in the favour of urban green sites and high-rise areas with commercial/residential function could be observed resulting in an increase of at least 20% in service supply budgets. Main contributors to the change are mainly the decrease of continuous urban fabric and industrial areas. The overall results and outcome of the study strengthen the suggested application of the proposed method for urban ecosystem service budget mapping with hitherto for that purpose unutilized high-resolution data. The insights and results from this study might further contribute to sustainable urban planning, prove common grounds for inter-urban comparisons or aid in enhancing ecological intra-urban functionality by analysing the distribution of urban eco-space and lead to improved accessibility and proximity to ecosystem services in urban areas

  • 62.
    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.

  • 63.
    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)
  • 64.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Spatio-temporal urban ecosystem service analysis with Sentinel-2A MSI dataManuscript (preprint) (Other academic)
    Abstract [en]

    Continuous urbanization changes the surface of our globe raising questions of sustainability, ecological functionality and living quality in metropolitan regions. Remote sensing enables us to obtain timely and reliable information on the state of urban areas and their changing patterns. The objectives of this study are to evaluate the contribution of Sentinal-2A data for urban ecosystem service mapping and to evaluate spatio-temporal characteristics of ecosystem service provisional patches through landscape metrics as an extension of the ecosystem service concept. Changes in service patterns over a 10-year time frame are mapped in the megacity of Beijing, China using Landsat TM data from 2005 and Sentinel-2A data from 2015. Landscape metrics are generated based on the classification results to evaluate the changes of urban ecosystem service provision bundles. The images are segmented using KTH-SEG, an edge-aware region growing and merging algorithm. The segments are then classified using a SVM classifier according to a classification strategy that is designed to distinguish between four natural and managed urban classes based on underlying ecosystem function and three artificial urban structures, i.e. buildings and roads that negatively influence ecosystem service provision to varying degrees and in different ways. These negative impacts are quantified through seven spatial attributes of green and blue patches and their configuration, namely area (CA), connectivity (COHESION), core area (TCA), diversity (SHDI), edge effects (CWED), percentage of land cover (PLAND) and a proximity measure. The 2015 classification accuracy of 90.2% was higher than the 2005 classification accuracy with 84.7%. Beijing’s urban development is characterized by a decrease in agricultural areas in the urban fringe in favour of new high and low density built-up areas, urban green space and golf courses. In total, high density and low-density urban areas have increased ca. 21%. Furthermore, the deconstruction of former high density low-rise suburban agglomerations into urban green space can be observed. The planar increase in urban areas is partly counteracted by the creation of managed urban green spaces. Ecosystem service bundles based on underlying land cover classes and similar spatial factors that influence service quality were derived for 2005 and 2015. Changes in landscape composition and configuration resulted in decreases of more than 30% in the bundles that represent food supply, noise reduction, waste treatment, global climate regulation. Temperature regulation/moderation of climate extremes, recreation/place values and social cohesion, aesthetic benefits/cognitive development and least affected by the observed land cover changes. The extension of the ecosystem service concept through spatio-temporal characteristics of ecosystem service provisional patches by landscape metrics is believed to give a more realistic appraisal of ecosystem services in urban areas.

  • 65.
    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.

  • 66.
    Haas, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Urban Land Cover and Ecosystem Service Changes based on Sentinel-2A MSI and Landsat TM Data2018In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 11, no 2, p. 485-497Article in journal (Refereed)
    Abstract [en]

    Sustainable development in metropolitan regions is challenging in the light of continuous urbanization. Remote sensing provides timely and reliable information on urban areas and their changing patterns. This study's objectives are to evaluate the contribution of Sentinel-2A (S-2A) data to urban ecosystem service mapping and to investigate spatial ecosystem service characteristics with landscape metrics through a novelmethod. Service pattern changes between 2005 and 2015 are mapped for Beijing, China. Landscape metrics are used to qualitatively evaluate urban ecosystem service provision bundle changes. S-2A and Landsat TM data are segmented and classified with SVM, distinguishing three artificial and four natural classes based on ecosystem function. Spatial characteristics influencing ecosystem services are quantified with seven landscape metrics. Beijing's urban development is characterized by reduction in agricultural areas in the urban fringe in favor of built-up areas, urban green space, and golf courses. A transformation of old suburban agglomerations into urban green space can be observed. The planar increase in urban areas is accompanied by the creation of managed urban green space. Service bundles based on land cover classes and spatial characteristics decreased more than 30% for bundles that represent food supply, noise reduction, waste treatment, and global climate regulation. Temperature regulation/moderation of climate extremes, recreation/place values/social cohesion, and aesthetic benefits/cognitive development are least affected. This new approach of extending the ecosystem service concept through integration of spatial characteristics of ecosystem service provisional patches through landscape metrics is believed to give a more realistic appraisal of ecosystem services in urban areas.

  • 67.
    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.

  • 68.
    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.

  • 69.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Medical Engineering.
    New approaches for surface water quality estimation in Lake Erken, Sweden, using remotely sensed hyperspectral data2011In: WSEAS Transactions on Environment and Development, ISSN 1790-5079, Vol. 7, no 10, p. 285-314Article in journal (Refereed)
    Abstract [en]

    This work demonstrates the efficiency of using linear statistical modelling for estimation ofconcentrations of various substances in lake water using remotely sensed multi- and hyperspectral imagestogether with extensive field measurements collected over Lake Erken in Sweden. A linear relationship wasassumed between image data and the corresponding field measurements, and the transformation coefficientswere estimated using the least squares method. The resulting coefficients were used to transform new imagedata into the corresponding substance concentrations. Estimation errors were computed and concentration mapswere generated for chlorophyll-a and phaeophytine-a, suspended particulate organic matter SPOM, suspendedparticulate inorganic matter SPIM, as well as total suspended particulate matter SPM (SPOM+SPIM). Goodcorrelation was obtained between estimated and measured values. Backward elimination was performed to findthe most useful spectral bands for the case study of this work. Descriptive spectral signatures, describing theimpact of underlying processes on the spectral characteristics of water, were generated, analysed and also usedto predict the corresponding water quality parameters in image data, with the same estimation accuracy as thelinear statistical model. Feature vector based analysis FVBA was also employed to generate transformationcoefficients that could be used to estimate water quality parameters from image data, also, with the sameaccuracy as the previous methods. Finally, the impact of performing atmospheric correction was investigated,in addition to applying linear statistical modelling for the purpose of combined atmospheric correction andground reflectance estimation.

  • 70.
    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.

  • 71.
    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.

  • 72.
    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)
  • 73.
    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.

  • 74.
    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.

  • 75.
    Hu, Hongtao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Li, P.
    Beijing University.
    A Quantitative Characterization of Spatial Structure Features of Typical Urban Land Cover Types Using Morphological Method2006In: IEEE International Geoscience and Remote Sensing Symposium, 2006, p. 3714-3716Conference paper (Other academic)
    Abstract [en]

    The analysis of spatial structure features in high resolution imagery is one of the most important research fields in remote sensing information processing. In this study, we attempt to quantitatively describe the differences of some spatial structure features of the selected urban land cover(use) types in 0.61-metre resolution Quickbird panchromatic imagery using morphological method. Gray-scale granulometry based on opening of each selected land use type with discs of increasing size provided a size distribution which indicates the prevailing sizes of the image structures and the corresponding volume measurement (sum of grey levels of all image pixels) losses at these sizes which are normalized. A series of directional openings with linear structuring elements were applied for each land use type and the predominant orientation of the land use type Was obtained by selecting the direction in which the volume measurement was maximal when opening was used. Also the strength of the predominant orientation information was obtained. Clear distinctions among different kinds of selected urban land use types were presented through the previously obtained prevailing sizes, normalized volume losses at these sizes, predominant orientation and its strength. It shows that these variables which reflect the size and orientation information could be integrated to characterize spatial structure features of urban land use types, which can be used in the extraction of some land use types from high resolution images.

  • 76.
    Hu, Hongtao
    et al.
    Peking University.
    Li, P.
    Beijing University.
    Segmentation of High-resolution Multi-spectral Image of Urban Areas Based on Extended Morphological Profiles2007In: 2006 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM, VOLS 1-8, IEEE , 2007, p. 3716-3719Conference paper (Refereed)
    Abstract [en]

    High-resolution multi-spectral remote sensing image of urban areas provides both structural and spectral information about urban scenes. In segmentation of such complex image scenes, very thin, enveloped or nested regions may have to be retained. Standard morphological segmentation approaches which are based on edge-detection do, not perform well for such scenes. In this study, segmentation of such images based on extended morphological profiles is proposed. First, fundamental morphological vector operations (erosion and dilation) are defined by extension, taking into account the spatial and spectral information in simultaneous fashion. Theoretical definitions of extended morphological operations are used in the formal definition of the concept of extended morphological profiles, which is constructed based on the repeated use of openings and closings by reconstruction with a structuring element (SE) of increasing size. Then, the morphological multi-scale characteristic of the image at each pixel is defined as the SE size with the greatest associated value in the corresponding derivative of the extended morphological profiles. The multi-scale segmentation derived from the morphological multi-scale characteristic could not be the final segmentation result because of over- or under- segmentation in local parts of the image. Therefore, appropriate post-processing is used to process the previous multi-scale segmentation to gain more accurate segmentation result. The proposed approach is applied to high-resolution multi-spectral QUICKBIRD imagery of urban areas. The experiment result demonstrates good performance of this approach.

  • 77.
    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)
  • 78.
    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.

  • 79.
    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.

  • 80.
    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.

  • 81.
    Jia, Yanjing
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Object-based Land Cover Classification with Orthophoto and LIDAR Data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

  • 82.
    Jing, Sun
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Semi-automated rapid damage assessment usinghigh-resolution satellite imagery: a case study of the 2008 Wenchuanearthquake, China2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 83.
    Karagöz, Hande
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Lightning Design.
    Urban Space Recreation for Pedestrians through Smart Lighting Control Systems2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Connected public lighting for more sustainable and liveable cities is highly demanding research in lighting design field through human centred design approach. While following this understanding, this thesis aims to answer the question “How a networked public lighting can be created in order to enhance the needs of the pedestrians in Fredhällspark?”. To investigate this study, a background research was studied in the relevant topics of urban lighting, followed by the study of human safety regarding to this topic and lastly the possible new lighting technologies. The main study is involved in a pedestrian path at Fredhällspark in Stockholm, Sweden, in two months duration in the spring time of 2018 by conducting user surveys and taking the lighting measurements. Based on the results the study showed, a lighting design proposal is developed with a site-specific approach in order to make it up-to date and sustainable for future urban environments while complying with the requirements of the users.

  • 84.
    Kolehmainen, Karoliina
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    MULTITEMPORAL SPOT IMAGES FOR URBAN LAND-COVER CHANGE DETECTION OVER STOCKHOLM BETWEEN 1986 AND 20042008In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2008Conference paper (Other academic)
    Abstract [en]

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

  • 85.
    Li, P.
    et al.
    Beijing University.
    Cheng, T.
    Beijing University.
    Hu, Hongtao
    Peking University.
    Xiao, X.
    Beijing University.
    High resolution multi-spectral image classification over urban areas by hierarchical image segmentation and composite kernel SVM2006In: The 2nd Workshop of the EARSel SIG on Land Use & Land Cover, 2006Conference paper (Other academic)
  • 86. Li, Peijun
    et al.
    Hu, Hongtao
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Guo, Jiancong
    Segmentation of high-resolution multispectral image based on extended morphological profiles2007In: IGARSS 2007: 2007 IEEE International Geoscience and Remote Sensing Symposium, IEEE , 2007, p. 1481-1484Conference paper (Refereed)
    Abstract [en]

    High-resolution multispectral remote sensing image provides both spectral and structural information about land cover/land use types. In segmentation of such complex image scenes with obvious texture, the efficient image segmentation is required. In this study, a method for high resolution image segmentation based on the extended morphological profiles is proposed. First, fundamental morphological vector operations (erosion and dilation) are defined by the extension, taking into account the spatial and spectral information in simultaneous fashion. Theoretical definitions of extended morphological operations are used in the formal definition of the concept of extended morphological profiles, which is constructed based on the repeated use of openings and closings by reconstruction with a structuring element (SE) of increasing size. Then, the morphological multiscale characteristic (MMC) of each pixel is gained through the derivative of the extended morphological profiles (DEMP). A modified method was proposed to obtain the right morphological characteristics of the pixel, which will be used for the final segmentation results. Finally, a simple region merging method based on the distance between two centroids of the neighboring regions was adopted to further improve the segmentation result. The proposed approach is applied to high-resolution QuickBird multispectral images from urban, agricultural and forest areas for evaluation and comparison with existing methods, in terms of qualitative visual inspection and quantitative criteria. The proposed method demonstrated better performance than the classical morphological segmentation approaches.

  • 87.
    LI, YUANXUN
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    SVM Object Based Classification Using Dense Satellite Imagery Time Series2018Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 88. Lundberg, C.
    et al.
    Reinhold, Roger
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Christensen, H. I.
    Evaluation of robot deployment in live missions with the military, police, and fire brigade2007In: Sensors, and Command, Control, Communications and Intelligence (C31) Technologies for Homeland Security and Homeland Defense VI, SPIE - International Society for Optical Engineering, 2007, p. 65380R-Conference paper (Refereed)
    Abstract [en]

    Robots have been successfully deployed within bomb squads all over the world for decades. Recent technical improvements are increasing the prospects to achieve the same benefits also for other high risk professions. As the number of applications increase issues of collaboration and coordination come into question. Can several groups deploy the same type of robot? Can they deploy the same methods? Can resources be shared? What characterizes the different applications? What are the similarities and differences between different groups? This paper reports on a study of four areas in which robots are already, or are about to be deployed: Military Operations in Urban Terrain (MOUT), Military and Police Explosive Ordnance Disposal (EOD), Military Chemical Biological Radiological Nuclear contamination control (CBRN), and Fire Fighting (FF). The aim of the study has been to achieve a general overview across the four areas to survey and compare their similarities and differences. It has also been investigated to what extent it is possible for the them to deploy the same type of robot. It was found that the groups share many requirements, but, that they also have a few individual hard constrains. A comparison across the groups showed the demands of man-portability, ability to access narrow premises, and ability to handle objects of different weight to be decisive; two or three different sizes of robots will be needed to satisfy the need of the four areas.

  • 89. Lundberg, C.
    et al.
    Reinhold, Roger
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Christensen, H. I.
    Results from a long term study of a portable field robot in urban terrain2007In: Unmanned Systems Technology IX, SPIE - International Society for Optical Engineering, 2007, p. 65610S-Conference paper (Refereed)
    Abstract [en]

    The military have a considerable amount of experience from using robots for mine clearing and bomb removal. As new technology emerges it is necessary to investigate the possibly to expand robot use. This study has investigated an Army company, specialized in urban operations, while fulfilling their tasks with the support of a PackBot Scout. The robot was integrated and deployed as an ordinary component of the company and included modifying and retraining a number of standard behaviors to include the robot. This paper reports on the following issues: evaluation of missions where the platform can be deployed, what technical improvements are the most desired, and what are the new risks introduced by use of robots? Information was gathered through observation, interviews, and a questionnaire. The results indicate the robot to be useful for reconnaissance and mapping. The users also anticipated that the robot could be used to decrease the risks of IEDs1 by either triggering or by neutralising them with a disruptor2. The robot was further considered to be useful for direct combat if armed, and for placing explosive loads against, for example, a door. Autonomous rendering of maps, acquiring images, two-way audio, and improved sensing such as IR were considered important improvements. The robot slowing down the pace of the unit was considered to be the main risk when used in urban operations.

  • 90. Luo, L.
    et al.
    Li, Z.
    Li, Shuo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Consistency testing of IP in mixed-signal SoC2007In: 2007 8th International Conference on Electronic Measurement and Instruments, ICEMI, IEEE , 2007, p. 265-268Conference paper (Refereed)
    Abstract [en]

    Based on the discussion, on the consistency description method used for SoC design, the testing method about the operation consistency of IP (Intellectual Property) blocks is addressed in this paper. The method proposed the guidance for designing the test vectors in mixed signal SoC design. With the method, logical description of operation consistency specification can be built in SoC design. This paper indicates that operation consistency design is a key point and will impact both architecture of hardware and software.

  • 91.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Generalisation of textured 3D city models using image compression and multiple representation data structure2013In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 79, p. 68-79Article in journal (Refereed)
    Abstract [en]

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

  • 92.
    Mazuelas Benito, Pablo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Fernández Torralbo, Ana
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Landsat and MODIS Images for Burned Areas Mapping in Galicia, Spain2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

  • 93.
    Mokhtary, Mandana
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Sensor Observation Service for Environmental Monitoring Data2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

  • 94.
    Mugiraneza, Theodomir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics. University of Rwanda, Rwanda.
    Haas, J.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Spatiotemporal analysis of urban land cover changes in Kigali, Rwanda using multitemporal landsat data and landscape metrics2017In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives, International Society for Photogrammetry and Remote Sensing , 2017, Vol. 42, no 3W2, p. 137-144Conference paper (Refereed)
    Abstract [en]

    Mapping urbanization and ensuing environmental impacts using satellite data combined with landscape metrics has become a hot research topic. The objectives of the study are to analyze the spatio-temporal evolution of urbanization patterns of Kigali, Rwanda over the last three decades (from 1984 to 2015) using multitemporal Landsat data and to assess the associated environmental impact using landscape metrics. Landsat images, Normalized Difference Vegetation Index (NDVI), Grey Level Co-occurrence Matrix (GLCM) variance texture and digital elevation model (DEM) data were classified using a support vector machine (SVM). Eight landscape indices were derived from classified images for urbanization environment impact assessment. Seven land cover classes were derived with an overall accuracy exceeding 88% with Kappa Coefficients around 0.8. As most prominent changes, cropland was reduced considerably in favour of built-up areas that increased from 2, 349 ha to 11, 579 ha between 1984 and 2015. During those 31 years, the increased number of patches in most land cover classes illustrated landscape fragmentation, especially for forest. The landscape configuration indices demonstrate that in general the land cover pattern remained stable for cropland but it was highly changed in built-up areas. Satellite-based analysis and quantification of urbanization and its effects using landscape metrics are found to be interesting for grassroots and provide a cost-effective method for urban information production. This information can be used for e.g. potential design and implementation of early warning systems that cater for urbanization effects.

  • 95.
    Mugiraneza, Theodomir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics. Centre for Geographic Information Systems and Remote Sensing, College of Science and Technology, University of Rwanda, KN 67 Street, Po Box 3900, Nyarugenge, Kigali, Rwanda.
    Nascetti, Andrea
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    WorldView-2 data for hierarchical object-based urban land cover classification in Kigali: Integrating rule-based approach with urban density and greenness indices2019In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 11, no 18, article id 2128Article in journal (Refereed)
    Abstract [en]

    The emergence of high-resolution satellite data, such as WorldView-2, has opened the opportunity for urban land cover mapping at fine resolution. However, it is not straightforward to map detailed urban land cover and to detect urban deprived areas, such as informal settlements, in complex urban environments based merely on high-resolution spectral features. Thus, approaches integrating hierarchical segmentation and rule-based classification strategies can play a crucial role in producing high quality urban land cover maps. This study aims to evaluate the potential of WorldView-2 high-resolution multispectral and panchromatic imagery for detailed urban land cover classification in Kigali, Rwanda, a complex urban area characterized by a subtropical highland climate. A multi-stage object-based classification was performed using support vector machines (SVM) and a rule-based approach to derive 12 land cover classes with the input ofWorldView-2 spectral bands, spectral indices, gray level co-occurrence matrix (GLCM) texture measures and a digital terrain model (DTM). In the initial classification, confusion existed among the informal settlements, the high- and low-density built-up areas, as well as between the upland and lowland agriculture. To improve the classification accuracy, a framework based on a geometric ruleset and two newly defined indices (urban density and greenness density indices) were developed. The novel framework resulted in an overall classification accuracy at 85.36% with a kappa coefficient at 0.82. The confusion between highand low-density built-up areas significantly decreased, while informal settlements were successfully extracted with the producer and user's accuracies at 77% and 90% respectively. It was revealed that the integration of an object-based SVM classification of WorldView-2 feature sets and DTM with the geometric ruleset and urban density and greenness indices resulted in better class separability, thus higher classification accuracies in complex urban environments.

  • 96.
    Mugiraneza, Theodomir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics. Univ Rwanda, Coll Sci & Technol, Ctr Geog Informat Syst & Remote Sensing, KN 67 St,POB 3900, Nyarugenge, Kigali, Rwanda..
    Nascetti, Andrea
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    WorldView-2 Data for Hierarchical Object-Based Urban Land Cover Classification in Kigali: Integrating Rule-Based Approach with Urban Density and Greenness Indices2019In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 11, no 18, article id 2128Article in journal (Refereed)
    Abstract [en]

    The emergence of high-resolution satellite data, such as WorldView-2, has opened the opportunity for urban land cover mapping at fine resolution. However, it is not straightforward to map detailed urban land cover and to detect urban deprived areas, such as informal settlements, in complex urban environments based merely on high-resolution spectral features. Thus, approaches integrating hierarchical segmentation and rule-based classification strategies can play a crucial role in producing high quality urban land cover maps. This study aims to evaluate the potential of WorldView-2 high-resolution multispectral and panchromatic imagery for detailed urban land cover classification in Kigali, Rwanda, a complex urban area characterized by a subtropical highland climate. A multi-stage object-based classification was performed using support vector machines (SVM) and a rule-based approach to derive 12 land cover classes with the input of WorldView-2 spectral bands, spectral indices, gray level co-occurrence matrix (GLCM) texture measures and a digital terrain model (DTM). In the initial classification, confusion existed among the informal settlements, the high- and low-density built-up areas, as well as between the upland and lowland agriculture. To improve the classification accuracy, a framework based on a geometric ruleset and two newly defined indices (urban density and greenness density indices) were developed. The novel framework resulted in an overall classification accuracy at 85.36% with a kappa coefficient at 0.82. The confusion between high- and low-density built-up areas significantly decreased, while informal settlements were successfully extracted with the producer and user's accuracies at 77% and 90% respectively. It was revealed that the integration of an object-based SVM classification of WorldView-2 feature sets and DTM with the geometric ruleset and urban density and greenness indices resulted in better class separability, thus higher classification accuracies in complex urban environments.

  • 97.
    Nickman, Alireza
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. KTH/ The Royal Institute of Technology.
    Road disasters? Modeling and assessment of Swedish roads within crucial climate conditions2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    An efficient maintenance of roads to ensure high accessibility and durability of the transport capacity requires an understanding of how the hydrological response depends on both the road and the landscape characteristics. New methods and data were used to identify and explain interaction between roads and surrounding environment and their influence on hydrologic responses both in watershed scale and road-section scale. In the watershed scale, flood hazard probability was made with reference to the most influential physical catchment descriptors and road characteristics. Additionally, a physical based model was used to estimate the effect of road topography on the hydrological responses of 20 watersheds to storms with different intensities. A simple method was developed and discussed to address flood risk probability in the road-stream crossings concerning the correlation between the quantities of the physical catchment descriptors and occurrence/absence of flooding. The most influential factors in describing the probability of flooding along the roads were topographic wetness index, soil properties, road density and channel slopes. A detailed study of simulated flow duration curves showed differences between the 20 watersheds for three different storms based on topography with and without roads. An increase in peak flow and reduced time to pick occurred with existence of roads and increased storm intensity.In the road-section scale, an uncertainty-based simulation approach was used to identify the most influencing processes in controlling the dynamics of the groundwater level. A model (CoupModel) set up with four different geological stratifications was made to model two positions in a slope upstream of a road with drainage pipes and ditches. Results from the simulations indicate the significance of precipitation rate, road drainage and position in hillslope, and soil properties and stratifications in controlling groundwater levels. The same model was also applied to simulate soil moisture and temperature dynamics in two road sections by using groundwater and climate data. Porous media properties were obtained as statistical distribution function that provided the best performance of moisture and temperature dynamic in the road layers and underlying soil.

  • 98.
    Nilsson, John-Olof
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Skog, Isaac
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Inertial Sensor Arrays - A Literature Review2016In: 2016 EUROPEAN NAVIGATION CONFERENCE (ENC), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    Inertial sensor arrays present the possibility of improved and extended sensing capabilities as compared to customary inertial sensor setups. Inertial sensor arrays have been studied since the 1960s and have recently received a renewed interest, mainly thanks to the ubiquitous micro-electromechanical (MEMS) inertial sensors. However, the number of variants and features of inertial sensor arrays and their disparate applications makes the literature spread out. Therefore, in this paper we provide a brief summary and literature review on the topic of inertial sensor arrays. Publications are categorized and presented in a structured way; references to +300 publications are provide. Finally, an outlook on the main research challenges and opportunities related to inertial sensor arrays is given.

  • 99.
    Niu, Xin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Multitemporal Spaceborne Polarimetric SAR Data for Urban Land Cover Mapping2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

  • 100.
    Niu, Xin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A Novel Contextual Classification Algorithm for Multitemporal Polarimetric SAR Data2014In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 11, no 3, p. 681-685Article in journal (Refereed)
    Abstract [en]

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

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