Change search
Refine search result
12 51 - 74 of 74
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Rusu, Lazar
    et al.
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    El Mekawy, Mohamed
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Hodosi, Georg
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Information Technology Leadership in Swedish Leading Multinational Corporations: A WEB SCIENCE PERSPECTIVE, PROCEEDINGS2009In: LECT NOTE ARTIF INTELL, 2009, Vol. 5736, p. 511-522Conference paper (Refereed)
    Abstract [en]

    This paper presents a comparative study of the Chief Information Officer (CIO) role, responsibilities, profile and the IT impact in five leading multinational corporations (MNCs) in Sweden. The first part of the paper comprehends a research review regarding the CIO role, responsibilities and barriers that the CIO is facing today in MNCs with references to the European business environment. After that in the second part of the paper a comparative analysis is provided regarding the CIO role, responsibilities and CIO profile using the Sojer et al. model [25] in the Swedish leading MNCs. Moreover the paper is providing in this part an analysis upon if the CIO is adding value by using Earl and Fenny profile [7]. In the last part of the paper an analysis is done concerning the IT impact in the Swedish MNCs by using McFarlan strategic grid framework [20] together with IT strategies used by the CIOs to support the business operations and strategies. The results of this analysis provide a detail overview that can be usefully for Swedish IT executives or top managers about the development of the CIO role, responsibilities and profile.

  • 52.
    Rymasheuskaya, Maryna
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301). Polotsk State University, Novopolotsk, Belarus .
    Comparison of several change detection methods for monitoring land cover dynamics in Belarus2007In: Proceedings of MultiTemp 2007 - 2007 International Workshop on the Analysis of Multi-Temporal Remote Sensing Images, 2007, p. 4293063-Conference paper (Refereed)
    Abstract [en]

    The study presents experience of use of post-classification comparison, image differencing, principal component analysis, use of ancillary data and combinations of different change detection methods for detecting land cover / land use dynamics in Novopolotsk area, Belarus over the period 1994-2002. All methods give good results in terms of accuracy assessment, visual presentation, etc. Change detection results are dependent on parameters applied.

  • 53.
    Rymasheuskaya, Maryna
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Land cover change detection in northern Belarus2007In: ScanGIS 2007 - Proceedings of the 11th Scandinavian Research Conference on Geographical Information Sciences, 2007, p. 255-260Conference paper (Refereed)
    Abstract [en]

    Study deals with the land cover dynamics analysis using remote sensing data over urban, suburban area in northern Belarus (Polotsk and Novopolotsk cities and surroundings) over the period 1994 - 2002. SPOT 3 and 5 images are used for the study. Land cover change detection is conducted using image differencing and post-classification comparison methods. Several classification methods are tested in order to obtain the best classification results to produce single date maps and change map.

  • 54. Sarker, M. L. R.
    et al.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Nichol, J.
    Comparison of pixel-based, object-based and sequential masking classification procedures for land use and land cover mapping using multiple sensor SAR in SWEDEN2007In: 28th Asian Conference on Remote Sensing 2007, ACRS 2007, 2007, p. 623-628Conference paper (Refereed)
    Abstract [en]

    Multiple sensor applications have become increasingly common in recent years and offer new opportunities to the remote sensing community to extract better information about the earth surface. However, the processing of multiple sensor SAR for land use and land cover mapping is not straightforward and still needs more investigation in order to become operational. This study investigates the efficiency of three different types of classification procedures, namely pixel-based, object-based and sequential masking to extract land use and land cover information from multiple sensor SAR images using the same training and validation areas. Four sensors (RADARSAT finebeam, RADARSAT standard-beam, ERS-2, and JERS-1) in different combinations were investigated in two study areas, to compare their effectiveness for accurate land cover mapping. The results indicate that the pixel-based classifier namely ANN is more accurate (around 90% overall accuracy and 0.90 Kappa coefficient) compared with object-based classification for extracting land use and land cover information from multiple sensor SAR. Overall it was found that the best performance (more than 90% overall accuracy and more than. 90 Kappa coefficient) can be achieved using a sequential masking approach because of its step by step classification technique.

  • 55. Sarker, M. L. R.
    et al.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Nichol, J.
    Potential of multisensor SAR for land use/land cover mapping in Sweden2009In: Proceedings of the 1st International Postgraduate Conference on Infrastructure and Environment, IPCIE 2009, 2009, p. 312-319Conference paper (Refereed)
    Abstract [en]

    The idea of multisensor data application has introduced a new dimension in the field of remote sensing in recent years. Very few attempts, however, have been made to use a multisensor approach, particularly multisensor Synthetic Aperture Radar (SAR) data for land use/land cover mapping. This research investigates the capability of spacebome multisensor SAR data, including RADARSAT fine-beam, RADARSAT standard-beam, ERS-2, and JERS-1, for extracting land use/land cover information in Sweden considering different sensor combinations (single sensor, double sensor, triple sensor and multisensor combinations), different image processing techniques (Raw, texture measures, filtered and combination of texture & filtered measures) and performance of various classification algorithms (MLC, ANN, k-NN, Sequential Masking and Object based classifier e-Cognition). The results demonstrate that despite the potential of multi-temporal single sensor SAR, the double, triple and multisensor SAR has a greater potential for land use/land cover mapping. But the potential of multisensor SAR for land use/land cover mapping depends on the characteristics of the combined sensors themselves, as well as the number of images. Among the different combinations, the best results was achieved using triple sensor combination (RADARSAT fine-beam, ERS-2, and JERS-1) because of its capability of providing the best complementary information, while the second and the third best results were obtained from multisensor combination (RADARSAT fine-beam, ERS-2, JERS-1 and RADARSAT standard-beam) and double sensor combination (ERS-2 and JERS-1) respectively. It is also revealed that the raw images produced very poor results using all combinations and all classifiers due to speckle noise, while the mean texture measures produced the best results using almost all combinations and classifiers. Remarkable variation was found among the performance of different classifiers with respect to different sensor combinations and different image processing techniques but ANN was clearly superior to the other classifiers with respect to all combinations and image processing techniques as a result of its non-parametric nature and its high mathematical base. The results indicate that the pixel-based classifier namely ANN is more accurate (around 90% overall accuracy and 0.90 Kappa coefficient) compared with object-based classification for extracting land use and land cover information from multiple sensor SAR. Overall it was found that the best performance (more than 90% overall accuracy and more than.90 Kappa coefficient) can be achieved using a sequential masking approach because of its step by step classification technique.

  • 56.
    Sarker, M.L.R.
    et al.
    University of Hong Kong.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Nichol, J.
    University of Hong Kong.
    Comparison of Pixel-based, Object-Based and Sequential Masking Classification Procedures for Land Use and Land Cover Mapping using Multiple Sensors SAR in Sweden2008In: Asian Journal of Geoinformatics, ISSN 1513-6728, Vol. 8, no 1, p. 25-30Article in journal (Refereed)
  • 57.
    Shirabe, Takeshi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Information on the Consequence of a Move and Its Use for Route Improvisation Support2011In: Spatial Information Theory: Cognitive and Computational Foundations / [ed] M. J. Egenhofer, N. A. Giudice, R. Moratz, M. F. Worboys, Berlin: Springer Berlin/Heidelberg, 2011, p. 57-72Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new method of navigational assistance in unfamiliar environments. In such environments, major concerns would normally be how to find a good route to a selected destination and how to design and communicate directions to follow that route. This may not be the case, however, if route selection criteria are not complete or subject to change during a trip. To cope with such uncertainty, the proposed method calculates, for each possible move from the current position, a single value characterizing the consequence of that move, e.g., how long it will take to reach the destination if that move is made. The paper outlines a design of a route improvisation support system equipped with this method, and underlines the merit of letting the user build up a route progressively by taking into account highly local, temporary, or personal information that is not stored in the system but collected by the user while traveling.

  • 58.
    Surur, Anwar
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Surveying, modelling and visualisation of geological structures in the Tunbergettunnel2008Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The 3-d visualisation of a section of the Tunberget tunnel and important fracture zones was accomplished by combination of the topographic surface, measurements at the surface of fracture planes together with surfaces of dolerite dykes, results from magnetic modeling of dolerite dykes and tunnel mapping data.

    The topographic surface was represented as elevation contours with 1 m equidistance. The fracture and dolerite surfaces were measured geodetically in the field from a net of 20 total station locations. Each surface was measured at 3 points to determine its strike and dip. Totally 44 strike and dip estimates were obtained. The extent at depth of the dolerite dykes was also estimated based on magnetic measurements along 3 profiles. The location of the dykes was also known from geological tunnel mapping.

    ArcGIS and RockWorks have been used to process the data and to generate a 3-d visualization of the geometrical relation between targeted geological structures, the dolerite dykes and the tunnel. The area is of interest to be studied in more detail as the fracture zones and the parallel dolerite dykes connect the tunnel with a large wetland complex.

  • 59.
    Tao, Jia
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Exploring Massive Volunteered Geographic Information for Geographic Knowledge Discovery2010Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Conventionally geographic data produced and disseminated by the national mapping agencies are used for studying various urban issues. These data are not commonly available or accessible, but also are criticized for being expensive. However, this trend is changing along with the rise of Volunteered Geographic Information (VGI). VGI, known as user generated content, is the geographic data collected and disseminated by individuals at a voluntary basis. So far, a huge amount of geographic data has been collected due to the increasing number of contributors and volunteers. More importantly, they are free and accessible to anyone.

     

    There are many formats of VGI such as Wikimapia, Flickr, GeoNames and OpenStreetMap (OSM). OSM is a new mapping project contributed by volunteers via a wiki-like collaboration, which is aimed to create free, editable map of the entire world. This thesis adopts OSM as the main data source to uncover the hidden patterns around the urban systems. We investigated some fundamental issues such as city rank size law and the measurement of urban sprawl. These issues were conventionally studied using Census or satellite imagery data.

     

    We define the concept of natural cities in order to assess city size distribution. Natural cities are generated in a bottom up manner via the agglomeration of individual street nodes. This clustering process is dependent on one parameter called clustering resolution. Different clustering resolutions could derive different levels of natural cities. In this respect, they show little bias compared to city boundaries imposed by Census bureau or extracted from satellite imagery. Based on the investigation, we made two findings about rank size distributions. The first one is that all the natural cities in US follow strictly Zipf’s law regardless of the clustering resolutions, which is different from other studies only investigating a few largest cities. The second one is that Zipf’s law is not universal at the state level, e.g., Zipf’s law for natural cities within individual states does not hold valid.

     

    This thesis continues to detect the sprawling based on natural cities. Urban sprawl devours large amount of open space each year and subsequently leads to many environmental problems. To curb urban sprawl with proper policies, a major problem is how to objectively measure it. In this thesis, a new approach is proposed to measure urban sprawl based on street nodes. This approach is based on the fact that street nodes are significantly correlated with population in cities. Specifically, it is reported that street nodes have a linear relationship with city sizes with correlation coefficient up to 0.97. This linear regression line, known as sprawl ruler, can partition all cities into the sprawling, compact and normal cities. This study verifies this approach with some US census data and US natural cities. Based on the verification, this thesis further applies it to three European countries: France, Germany and UK, and consequently categorizes all natural cities into three classes: sprawling, compact and normal. This categorization provides a new insight into the sprawling detection and sets a uniform standard for cross comparing sprawling level across an entire country.

  • 60.
    Tao, Zhang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Application of GIS and CARE-W systemson water distribution networks inSkärholmen in Stockholm2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Urban infrastructure management is becoming more and more important for cities around theworld. This paper presents a management and rehabilitation strategy for water distributionnetworks, which is to ensure that they are economically under a healthy condition over anextended period of time. The idea is to pay more attention on pro- active approaches thatuse predictive analysis to achieve long- term economic efficiency.One target in this project is to integrate Geographic Information System technology andComputer Aided Rehabilitation of Water Networks (CARE-W), a new developed toolkit inEurope. This thesis also aims to study and evaluate water distribution condition by using datafrom Stockholm Water Company in Sweden. Moreover the reliability of CARE-W toolkit istested. It concluded the experience including theory review, data preparation, and integrateprocess and achievement presentation.The test area is called Skärholmen pressure zone, consisting 4060 water mains and about1580 failures, which were recorded from year 1988 to 2005. In the experiment, datapreparation and analysis processes occupied above 80% of the project time. Three CARE-Wtools have been tested. They are Performance Indicator tool, Reliability Model and FailureModel. The Performance Indicator Tool and Reliability Model were run successfully, but theFailure Model failed in this project. However another approach from only GIS analysis hasbeen carried to achieve failure forecasting.In the final part, why some portions are in poorer positions compared to others are discussedbased on reality and results from the experience. Results are presented in graphs, GIS mapsand tables. These are mainly for decision makers to know the current situation of their assetand where they should put more energy on and how to make long term planning.

  • 61.
    Vu, Tuong Thuy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Context-based mapping of damaged buildings from high-resolution optical satellite images2010In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 31, no 13, p. 3411-3425Article in journal (Refereed)
    Abstract [en]

    In the early stages of post-disaster response, a quick and reliable damage assessment map is essential.As time is a critical factor, automated damage mapping from remotely sensed images is the expected solution to drastically reduce data acquisition and computation time. Recently, high-resolution satellite images, such as QuickBird data, have been in high demand by damage assessment analysts and disaster management practitioners. However, the existing automated mapping approaches hardly accommodate such high-resolution data. This research aims at developing a new context-based automated approach for earthquake damage mapping from high-resolution satellite images. Relevant contextual information (including structure, shape, size, edge texture, spatial relations) describing the damage situation is formulated and up-scaled on a morphological scale-space. Speed optimization is achieved by parallel processing implementation. The developed approach was tested with two QuickBird images acquired on 26 June 2005 and 3 June 2008 over YingXiu town, Sichuan, China, which suffered the devastating 12 May 2008 earthquake. In comparison to the reference, the developed mapping approach could achieve over 80% accuracy for computation of the damage ratio. Future research is planned to test the approach on various disaster cases for both optical and radar images using a grid-computing platform towards a cost-effective damage mapping solution.

  • 62.
    Vu, Tuong Thuy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Fusion of ENVISAT ASAR and HJ-1 Multispectral Data for Urban Land Cover Mapping2010In: Proceedings, ESA Living Planet Symposium, 2010, 2010Conference paper (Other academic)
  • 63.
    Vu, Tuong Thuy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Matsuoka, Masashi
    AIST.
    Towards a quick damage detection system based on grid-computing2010In: Geographic Information and Cartography for Risk and Crisis Management: Towards Better Solutions / [ed] KONECNY M., ZLATANOVA S. and BANDROVA T.L, Springer Berlin/Heidelberg, 2010, p. 155-170Chapter in book (Refereed)
    Abstract [en]

    This chapter develops a quick damage detection system prototype, which produces reasonably detailed information of damaged buildings and accommodates high spatial resolution data. Parallel processing based on grid-computing is chosen to reduce computation time as well as to provide end-users with cost-effective access. The clusters of the GEO (Global Earth Observation) Grid system (www.geogrid.org) at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan will serve as the main platform. The automated damage detection runs through a scale-space analysis . It is developed as a context-based approach integrating texture, shape, size, and spectral reflectance. QuickBird imagery acquired over Yingxiu town which was heavily damaged due to the 2008 Sichuan Earthquake is used to demonstrate the performance of damage detection algorithms. Damage information at building block level is successfully mapped. At the current stage of development, damage detection focuses on producing quick orientation damage maps. The data grid component of the GEO Grid with data federation capability will be employed to connect to various satellite image and field-survey databases in the next stage of development. This is to enhance the mapping capability for more accurate maps. In addition, future work will practically perform the processing of large-scale damage detection on the GEO Grid , and test the system performance with remote sensing data acquired in various catastrophes.

  • 64.
    Vu, Tuong Thuy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Yamazaki, Fumio
    Matsuoka, Masashi
    Multi-scale solution for building extraction from LiDAR and image data2009Article in journal (Refereed)
    Abstract [en]

    This paper presents a multi-scale solution based on mathematical morphology for extracting the building features from remotely sensed elevation and spectral data. Elevation data are used as the primary data to delineate the structural information and are firstly represented on a morphological scale-space. The behaviors of elevation clusters across the scale-space are the cues for feature extraction. As a result, a complex structure can be extracted as a multi-part object in which each part is represented on a scale depending on its size. The building footprint is represented by the boundary of the largest part. Other object attributes include the area, height or number of stories. The spectral data is used as an additional source to remove vegetation and possibly classify the building roof material. Finally, the results can be stored in a multi-scale database introduced in this paper. The proposed solution is demonstrated using the data derived from a Light Detection And Ranging (LiDAR) surveying flight over Tokyo, Japan. The results show a reasonable match with reference data and prove the capability of the proposed approach in accommodation of diverse building shapes. Higher density LiDAR is expected to produce better accuracy in extraction, and more spectral sources are necessary for further classification of building roof material. It is also recommended that parallel processing should be implemented to reduce the computation time.

  • 65.
    Wiman, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Qin, Yuchu
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Fast Compression and Access of LiDAR Point Clouds Using Wavelets2009In: 2009 JOINT URBAN REMOTE SENSING EVENT, NEW YORK: IEEE , 2009, p. 718-723Conference paper (Refereed)
    Abstract [en]

    To compress, access, visualize and analyze large 3D point clouds, they are often converted to Digital Surface Models, either as raster grids or Triangulated Irregular Networks. This paper proposes an approach, which works directly on the points as they were recorded during data capture. There is usually a strong correlation between successively recorded points. This correlation is used to compress the point clouds using wavelet transforms. The characteristics of wavelet coefficients are used to access areas of progressively higher resolution and quality. The detail coefficients can also be used for 3D analysis and reconstruction.

  • 66. Xia, J.
    et al.
    Du, P.
    Liu, P.
    Shan, D.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Quantifying spatio-temporal change of urban land cover/use and landscape pattern using BJ-1 and CBERS remote sensing images: A case study of Shanghai2010In: 2010 Dragon 2 Mid Term Results Symposium, 2010Conference paper (Other academic)
    Abstract [en]

    The overall objective of this research is to investigate the effectiveness of BJ-1 and CBERS remote sensing images for monitoring and modeling the spatial-temporal pattern change in Shanghai city. In this study, a scene of BJ-1 and two scenes of CBERS 01/02 images were used as the data sources. Comparing the accuracy of maximum likelihood classifier (MLC) and support vector machine (SVM) with two different kernel functions, the highest one in each temporal was chosen to analyze the typical ground objects and landscape pattern change. Gradient and direction characteristic analysis were also applied to calculate the degree and direction of urban growth. We selected some human and natural indicators from the Shanghai Statistical Yearbook to analyze the driving force of Shanghai. The results indicated that urbanization in Shanghai tended to be marginalization. And the urban growth has occurred in the NE-E and SE-S direction regions (Pudong New Area and Sanlin Area).

  • 67. Xia, J.
    et al.
    Du, P.
    Zhang, H.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Yuan, L.
    Monitoring urban impervious surface growth in Xuzhou using CBERS and BJ-1 Remote Sensing images2010In: 2010 Dragon 2 Mid Term Results Symposium, 2010Conference paper (Other academic)
    Abstract [en]

    As the study area, Xuzhou City was chosen, located in the northwestern of Jiangsu Province, China. And two CBERS images and one BJ-1 small satellite image were employed to impervious surface extraction. Using multi-layer perception (MLP) neural network, all pixels were decomposed to the four fraction images representing the abundance of four endmembers: vegetation, high-albedo objects, low-albedo objects and soil. Then, the impervious surface was derived by the combination of high-albedo and low-albedo fraction images after removing the influence of water body. Furthermore, ALOS Pan high resolution image, that covering the city center of study area were selected to validate the impervious surface estimation results and evaluate the accuracy of impervious surface extraction. By comparing the urban impervious surface abundance from three remote sensing images, the change pattern of impervious surface was studied. The past years saw the impervious surface had been grown rapidly in Xuzhou City, especially in the north-east region, and south-east (Tongshan New District, Nanhu Campus of China University of Mining and Technology (CUMT)).

  • 68. Xia, Junshi
    et al.
    Du, Peijun
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Evaluation of spatial pattern of urban heat island and its relationship with land cover by HJ-1 remote sensing images - A case study of Shanghai City2010In: 2010 Dragon 2 Mid Term Results Symposium, 2010Conference paper (Refereed)
    Abstract [en]

    In the study, multi-spectral data with 30m resolution and hyperspectral images with 100m resolution are used to classify the land cover into six types: water body, public green space, agriculture land, built-up areas and non-use land, clouds, while thermal images with 300m resolution are used to evaluate the urban heat island effect. The field work at Sep 17th, 2009 is used to evaluate the accuracy of classification results. In order to quantify the degree along the rural-urban gradient, Moran's I index and semi-variance are used to assess the spatial autocorrection and describe the scale and pattern of spatial variability. The results show that the land cover map resulted from multi-spectral image has satisfactory accuracy. From the results of Moran' I index and semi-variance, it indicats that spatial pattern of homogeneous patches exist on small scales smaller 36km, meso scales between 36-81km and large scales bigger than 81km. The relationship between land cover types and UHI patterns is also studied.

  • 69. Xueyan, Zhang
    et al.
    Yunfeng, Hu
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Dafang, Zhuang
    Yongqing, Qi
    Xin, Ma
    NDVI spatial pattern and its differentiation on the Mongolian Plateau2009In: JOURNAL OF GEOGRAPHICAL SCIENCES, ISSN 1009-637X, Vol. 19, no 4, p. 403-415Article in journal (Refereed)
    Abstract [en]

    GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north, areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was indicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVI spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.

  • 70. Yamazaki, F.
    et al.
    Liu, W.
    Vu, Tuong Thuy
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Vehicle extraction and speed detection from digital aerial images2008Conference paper (Refereed)
    Abstract [en]

    A new object-based method is developed to extract the moving vehicles and subsequently detect their speeds from two consecutive digital aerial images automatically. Several parameters of gray values and sizes are examined to classify the objects in the image. The vehicles and their associated shadows can be discriminated by removing big objects such as roads. To detect the speed, firstly the vehicles and shadows are extracted from the two images. The corresponding vehicles from these images are linked based on the order, size, and their distance within a threshold. Finally, using the distance between the corresponding vehicles and the time lag between the two images, the moving speed can be detected. Our test shows a promising result of detecting the moving vehicles' speeds. Further development will employ the proposed method for a pair of QuickBird panchromatic and multi-spectral images, which are at a coarser spatial resolution.

  • 71. Yin, D.
    et al.
    Chen, B.
    Huang, Z.
    Lin, Xin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301). Peking University,China.
    Fang, Y.
    Utility based query dissemination in spatial data grid2007In: Proceedings of the 6th International Conference on Grid and Cooperative Computing, GCC 2007, IEEE Computer Society, 2007, p. 574-581Conference paper (Refereed)
    Abstract [en]

    Spatial Information Grid is an ideal infrastructure to handle the data-intensive and computing-intensive geo-spatial processing. In order that each agency could ad hoc connect to this computing environment and make autonomous decision, we build a Geospatial Data Grid in peer-to-peer way. The query processor module in each peer can decompose the user's query into sub-queries that executed in different nodes. One problem in the parallel spatial join query optimization is how to determine an appropriate node group to disseminate the sub-queries. Especially, if there is more than one node sharing the same area of interest, there is a dilemma: on the one hand, the task scheduler tends to decompose this query into sub-queries and disseminate them to as many as possible nodes so that they could process the user's query in parallel; on the other hand, recruiting too many nodes will also bring in overhead in repetitive computing, redundant data transmission, and the result merging. Based on the study of trade-off between increasing parallelism and reducing redundancy using the Utility Theory in economics, we put forward a fast node selection algorithm for the parallel spatial join query dissemination. The test in our system shows this strategy could balance the above two conflict demands and is appropriate for use in Data Grid.

  • 72.
    Yousif, Osama A.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Multitemporal Spaceborn SAR Data For Change Detection In Urban Areas: A Case Study In Shanghai2009In: Proceedings, ISPRS Virtual Changing Globe for Visualization and Analysis / [ed] Jianya Gong,Qiming Zhou, 2009Conference paper (Other academic)
    Abstract [en]

    The objective of this research is to perform automatic change detection within urban areas using multitemporal spaceborne SAR datain Shanghai. Two scenes of ENVISAT ASAR C-VV images were acquired in September, 2008 and one scene of ERS-2 SAR C-VVimage was acquired in September, 1999. A generalized version of Kittler Illingworth minimum-error thresholding algorithm, thattakes into account the non-Gaussianity of SAR images, was tested to automatically classify the SAR ratio image into two classes,change and no change. Two types of comparison operators were performed. First, the conventional ratio image was calculated in away that only increases in backscatter coefficient are detected. Second, a modified ratio operator that takes into accounts bothpositive and negative changes was also examined. Various probability density functions such as, Log normal, Generalized Gaussian,Nakagami ratio, and Weibull ratio were tested to model the distribution of the change and no change classes. An iterative refinementof the Log normal model is also applied to improve the resolution of the change map. The preliminary results showed that thisunsupervised change detection algorithm is very effective in detecting temporal changes in urban areas using SAR images. The bestchange detection result was obtained using Log normal model with modified ratio operator at 81.5%, which is over 10% high thanthat of the other three models tested. The initial findings indicated that change detection accuracy varies depending on how theassumed conditional class density function fits the histograms of change and no change classes.

  • 73.
    Yousif, Osama A.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics. KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301). 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.
    Object-based change detection in urban areas using multitemporal high resolution SAR images with unsupervised thresholding algorithms2016In: Remote Sensing and Digital Image Processing, Springer, 2016, p. 89-105Chapter in book (Refereed)
    Abstract [en]

    With the recent launches of optical and SAR systems that are capable of producing images in very high resolution, the quantification of temporal changes can be achieved with unprecedented level of details. However, very high resolution data presents new challenges and difficulties such as the strong intensity variations within land cover classes thus the noisy appearance of change map generated by pixelbased change detection. This has led to the development of object-based approaches that utilize image segmentation. For unsupervised change detection, on the other hand, automatic thresholding algorithms provided a simple yet effective technique to produce a binary change map. Thresholding techniques have been used successfully for pixel-based change detection using medium resolution SAR images. They have also been used for object-based change detection using high resolution optical imagery. However, they have not been tested in the context of object-based change detection using high resolution SAR images. Therefore, this chapter investigates the potential of several thresholding techniques for object-based unsupervised detection of urban changes using high resolution SAR images. To avoid the creation of sliver polygons, the multidate image segmentation strategy is adopted to produce image objects that are spectrally, spatially, and temporally homogeneous. A change image is generated by comparing objects multitemporal mean intensities using the modified ratio operator. To threshold the change image and generate a binary change map, three thresholding algorithms, i.e., the Kittler-Illingworth algorithm, the Otsu method, and the outlier detection technique, are tested and compared. Two multitemporal datasets consisting of TerraSAR-X images acquired over Beijing and Shanghai are used for evaluation. Quantitative and qualitative analyses reveal that the three algorithms achieved similar results. The three algorithms achieved Kappa coefficients around 0.6 for the Beijing dataset and 0.75 for the Shanghai datasets. The analysis also reveals the limitation of the mathematical comparison operator in accentuating the difference between the changed and the unchanged class, thus calls for the development of more sophisticated object-based change image generation mechanisms capable of reflecting all types of changes in the complex urban environment.

  • 74.
    Zhang, Qian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Evaluation of urban expansion and its impact on surface temperature in Beijing, China2011In: IEEE GRSS and ISPRS Joint Urban Remote Sensing Event, JURSE 2011, 2011, p. 357-360Conference paper (Refereed)
    Abstract [en]

    This paper reports an investigation into the urban expansion in Beijing during 2004-2009 and its impact on land surface temperature (LST), as well as the relationship between LST and NDVI. LST and landuse/land-cover (LULC) data were extracted from Landsat Thematic Mapper (TM) images acquired on September 8, 2004 and September 22, 2009. The spatial pattern of LST before and after the 2008 Summer Olympic Games in Beijing were compared. The change detection results revealed that the increase of the built-up areas of approximately 139.19km 2 during 2004 to 2009 and this accounted for approximately 4% of the study area. The spatial pattern of LST was non-symetrical and non-concentric. The high temperature zones clustered towards the south of the central axis and extend to the fifth ring road in 2004, while this situation was relieved in 2009. The correlation analysis indicated that LST values tend to negatively correlate with NDVI in both years with the coefficients of -0.751 and -0.732 correspondingly. Moreover, the overall changes of NDVI accounted for approximately 40% of the LST changes.

12 51 - 74 of 74
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf