Papers by Sigrid Roessner
Remote Sensing of Environment, 2007
Hyperspectral remote sensing data open up new opportunities for analyzing urban areas characteriz... more Hyperspectral remote sensing data open up new opportunities for analyzing urban areas characterized by a large variety of spectrally distinct surface materials. Spectroscopic analysis using diagnostic spectral features yields the potential for automated identification and mapping of these materials. This study proposes a new approach for the determination and evaluation of such spectral features that are robust against spectral overlap between material classes and within class variability. Analysis is based on comprehensive field and image spectral libraries of more than 21.000 spectra of surface materials widely-used in German cities. The robustness of the interactively defined spectral features is evaluated by a separability analysis. This method is performed based on confusion matrices for each material computed from classification results. For comparison this analysis is also performed for material-specific gray values of selected bands. The obtained commission and omission errors show superiority of the spectral features compared to gray values for most of the investigated materials. The results indicate that robust spectral features yield the potential for unsupervised detection of endmembers in hyperspectral image data.
... This study presents an application of Landsat imagery and GIS techniques to the study of chan... more ... This study presents an application of Landsat imagery and GIS techniques to the study of channel migration in a large river system. ... In order to maintain consistency for interpreting 147 Remotesensing and GIS for channel change analysis timesequence images, we defined ...
... determined. In this study the potential of combining information derived from satellite remot... more ... determined. In this study the potential of combining information derived from satellite remote sensing data with information obtained from geological maps and field observations are investigated in a GIS environment. For this ...
IEEE/ISPRS Joint Workshop on Remote Sensing and Data Fusion over Urban Areas (Cat. No.01EX482), 2001
In this study a spectral library was developed, which forms the database for an area-wide identif... more In this study a spectral library was developed, which forms the database for an area-wide identification of urban surface materials using hyperspectral HyMap data. Spectra are measured with a field spectrometer in the wavelength range between 0.35-2.5 μm in 2151 channels. For the systematic assessment of materials the urban surface is categorized in regard to its degree of surface sealing
22nd Digital Avionics Systems Conference. Proceedings (Cat. No.03CH37449), 2003
Absfracf-Urban biotope mapping is the most important database for ecological urban planning. The ... more Absfracf-Urban biotope mapping is the most important database for ecological urban planning. The mapping contains complex information about the outfit and structure of biotopes in form of descriptive parameters. However, quantitative parameters are limited to a manual estimation of five levels of surface sealing. Therefore, municipal authorities are interested in quantitative pammeters for an advanced GIS-based evaluation of urban biotopes. In this study airbome hyperspeceal HyMap data are analyzed to identify urban surface materials based on their material specific reflectance features. The small urban structures and the high spectral information content of the hyperspectral image data require advanced methods for surface identification. Thus, a combined classification and unmixhg approach was applied [I]. The resulting dataset includes surface abundances of spectrally different materials and forms the basis for the derivation of quantitative parameters for each biotope, such as the weighted surface sealing and the portion of overbuilt area. Spatial and statistical analyses show that the results represent a contribution towards a n improved quantitative evaluation of biotopes. In this way valuable remote sensing based parameters can be integrated into ecological urban planning processes. Index Terms-Eypetspectral EyMap data, urban analysis, urban biotope mapping, surface sealing.
In Kyrgyzstan (Central Asia) large landslides are widespread at the eastern rim of the Fergana Ba... more In Kyrgyzstan (Central Asia) large landslides are widespread at the eastern rim of the Fergana Basin in an area of active mountain building (Pamir-Tien Shan). Because of the large number of landslides and their difficult accessibility in mountainous terrain the potential of GIS-based analysis of satellite remote sensing data is investigated. This goal requires a spatially and thematically consistent digital database including high resolution digital topographic data as a key element. For this purpose a Digital Elevation Model (DEM) was generated from data of the German multi-line scanner MOMS-2P (Modular Optoelectronic Multispectral Scanner). Processing steps included automated image matching for tie point generation between the 3 stereo strips, photogrammetric block adjustment for reconstructing the exterior and interior orientation of the camera, and finally DEM interpolation. Geodetic GPS measurements were carried out to determine ground control points (GCP) for photogrammetric point determination and independent check points (CP) for assessment of height accuracy of the final DEM. Height accuracy is described by mean and standard deviation of differences between GPS and DEM heights and amounts to 1.1 +/-17.3m based on 36 CP. In a second step, orthoimages of the 4 MOMS-2P channels were derived. Both MOMS-2P stereo products were analyzed for their suitability investigating landslide phenomena in the Maili-Suu test area. GIS-based analysis including perspective visualizations, surface profiling and derivation of quantitative relief parameters led to topography-based identification of tectonically active elements as one major factor for initiating landslides. The stereo products also allowed detailed analysis of a single landslide. In case of the Kashgarta landslide spatial interference between displaced masses and surrounding stable areas was investigated incorporating geological information. These investigations showed that height accuracy and morphological detail of MOMS-2P stereo products are appropriate for regional satellite remote sensing based analysis of landslide processes in this area.
Large landslides are one of the main natural hazards in Kyrgyzstan. Because of the high number of... more Large landslides are one of the main natural hazards in Kyrgyzstan. Because of the high number of landslides and their relative inaccessibility in mountainous terrain the potential of satellite remote sensing in combination with GIS-based analysis has been investigated in the frame of a collaboration with the Ministry of Emergency and Environment (MEE) in Kyrgyzstan. Emphasis is put on the development of multi-temporal remote sensing techniques to support landslide inventories and characterisation of main terrestrial factors preconditioning landslides on a regional scale. The database consists of Landsat-TM, stereoscopic MOMS-2P and radar (ERS-1/2) satellite imagery. MOMS-2P and ERS-1/2 data allowed the generation of high-resolution Digital Elevation Models (DEM). The derived relief parameters have been analysed in a GIS in combination with other information obtained from remote sensing data, thematic maps and field observation for a spatially differentiated characterisation of terrain properties as a basis for further assessment of landslide hazard. Future work will focus on investigating the potential of most recent and upcoming satellite missions (SRTM, ENVISAT and ASTER) for landslide analysis, since this research has been approved for pilot projects in the corresponding announcements of opportunity.
Remote Sensing, 2015
ABSTRACT This study focuses on evaluating the potential of ALOS/PALSAR time-series data to analyz... more ABSTRACT This study focuses on evaluating the potential of ALOS/PALSAR time-series data to analyze the activation of deep-seated landslides in the foothill zone of the high mountain Alai range in the southern Tien Shan (Kyrgyzstan). Most previous field-based landslide investigations have revealed that many landslides have indicators for ongoing slow movements in the form of migrating and newly developing cracks. L-band ALOS/PALSAR data for the period between 2007 and 2010 are available for the 484 km2 area in this study. We analyzed these data using the Small Baseline Subset (SBAS) time-series technique to assess the surface deformation related to the activation of landslides. We observed up to ±17 mm/year of LOS velocity deformation rates, which were projected along the local steepest slope and resulted in velocity rates of up to −63 mm/year. The obtained rates indicate very slow movement of the deep-seated landslides during the observation time. We also compared these movements with precipitation and earthquake records. The results suggest that the deformation peaks correlate with rainfall in the 3 preceding months and with an earthquake event. Overall, the results of this study indicated the great potential of L-band InSAR time series analysis for efficient spatiotemporal identification and monitoring of slope activations in this region of high landslide activity in Southern Kyrgyzstan.
This study evaluates the potential of Landsat imagery to study surface velocity field associated ... more This study evaluates the potential of Landsat imagery to study surface velocity field associated with the Inylchek Glacier in Kyrgyzstan. More than 70 Landsat images acquired over the region in the past decade were investigated and analyzed to derive the kinematics of the Inylchek. Our preliminary result indicates a high-velocity region in the elevated part of the glacier moving at a rate of about 0.5 meter/day during the 2002-2003 time period. Time series analysis reveals some annual variations in the mean surface velocity of the Inylchek during 2002-2009.
Southern Kyrgyzstan is part of the tectonically active mountain ranges of the Tien Shan. The stud... more Southern Kyrgyzstan is part of the tectonically active mountain ranges of the Tien Shan. The study area is located at the Eastern rim of the Fergana Basin representing a densely populated region where large landslides regularly endanger human lives and infrastructure. Therefore, GIS-based landslide susceptibility and hazard analysis is of great importance requiring detailed assessment of past landslide activity at regional scale. In Kyrgyzstan, information on past landslide activity is less available than in other more developed and researched regions of the world. Although landslide investigations were conducted since the 1950s, they have been drastically reduced since Kyrgyzstan's independence from the former Soviet Union in 1991 accompanied by loss of existing information. During the last years, information on landslides has been made publicly available mostly in form of derivatives, such as landslide hazard maps. All of these investigations have been limited to inhabited are...
Southern Kyrgyzstan is a region of high landslide activity frequently endangering human lives and... more Southern Kyrgyzstan is a region of high landslide activity frequently endangering human lives and infrastructure. So far, precise spatio-temporal information on landslide occurrence has been limited, although in this region landslide activity has been investigated for the last 60 years by local authorities with the goal of protecting people from the consequences of catastrophic slope failures. The objective of the presented research is the development of a satellite remote sensing and GIS-based approach for the establishment of a spatially and temporally consistent multi-temporal landslide inventory at a regional scale for the area of approx. 12000 sq km characterized by high landslide activity. Such an inventory is one of the main prerequisites for probabilistic landslide hazard assessment. For this purpose, multiple sources of information about slope failures have been analyzed in regard to their GIS-based integration into a single system with a common spatial reference. They incl...
The strong topographic relief and the presence of weakly consolidated sediments create favorable ... more The strong topographic relief and the presence of weakly consolidated sediments create favorable conditions for the development of mass movements in large areas of Central Asia. At the GFZ German Research Centre for Geosciences we are studying such gravitational mass movements in a multidisciplinary and both process-oriented and application-based way, focusing on better understanding of the triggering and motion-controlling factors. Development of automated remote sensing methods for spatial mapping and monitoring of mass movements using optical and radar remote sensing as well as Bayesian statistics and Geographic Information System (GIS) technology for regional hazard assessment are complemented by temporal monitoring of mass motion processes using seismological methods. The combination of novel passive seismic imaging technologies and the use of wireless sensors allows the rapid construction of inexpensive, spatially dense and self-organizing communication networks that can respo...
The presented work has investigated the potential of optical and radar satellite remote sensing f... more The presented work has investigated the potential of optical and radar satellite remote sensing for enabling dynamic landslide hazard assessment at a regional scale. For this purpose a large multi-temporal satellite remote sensing database has been established for a 12000 km2 study area in Southern Kyrgyzstan including a multitude of optical data covering the last 25 years as well as TerraSAR-X and ALOS-PALSAR radar data which have been available for this region since 2007. Optical data have been mainly used for the establishment of a GIS-based dynamic landslide inventory and spatially differentiated characterization of pre-disposing factors with emphasis on structural and tectonic control of landslide occurrence. Radar data analysis has been focused on SAR Interferometry (InSAR) in order to detect surface deformation related to mass movements. The used GIS-based system allows combination of all of the obtained landslide-related information regardless of their initial source and met...
Southern Kyrgyzstan is a mountainous region affected by ongoing high tectonic activity leading to... more Southern Kyrgyzstan is a mountainous region affected by ongoing high tectonic activity leading to frequent occurrence of destructive earthquakes and mass movements. Since large areas are affected, there is a big need for efficient analysis and monitoring of these hazardous processes. In this study we use radar satellite remote sensing, in particular L-band ALOS/PALSAR and C-band ENVISAT imagery to analyze surface deformation related to earthquakes and mass movements by applying SAR interferometry (InSAR) and pixel offset techniques. We present two case studies: (1) The Nura earthquake which occurred on 5th October 2008 with magnitude 6.6 at the eastern termination of the intramontane Alai valley between the southern Tien Shan and the northern Pamir. Our SAR data analysis has revealed a spatially differentiated signal of the surface deformation related to the earthquake showing clear gradients in the vertical and horizontal directions along a complex pattern of surface ruptures and a...
Photogrammetrie - Fernerkundung - Geoinformation, 2015
ABSTRACT In Southern Kyrgyzstan, landslides regularly endanger human lives and infrastructure. Th... more ABSTRACT In Southern Kyrgyzstan, landslides regularly endanger human lives and infrastructure. They are a very dynamic phenomenon with significant variations of the process activity in different years. This creates a need for the development of new methods of dynamic and spatially differentiated landslide hazard assessment at a regional scale. Because of the large size of the study area (over 12,000 km2), remote sensing data are a valuable and reliable source of detailed and consistent spatial information for landslide investigations in Southern Kyrgyzstan. The paper demonstrates how GIS and remote sensing techniques are used for the acquisition, verification and homogenization of heterogeneous multi-source landslide data with the goal of generating a multi-temporal landslide inventory. Special emphasis is placed on the spatial data consistency, the documentation of temporal information and the possibility to document repeated slope failures within the same slope. The multi-temporal landslide inventory is an integral part of a landslide inventory information system, which is implemented in the QGIS environment and provides self-customized functionality for data queries and spatial analysis including the derivation of landslide attributes. The information system contains additional spatial base data such as a spatially consistent multi-temporal archive of satellite images and topographic maps. German In Südkirgistan werden durch Hangrutschungsereignisse regelmäßig Menschenleben sowie technische und soziale Infrastruktur gefährdet. Da die Hangrutschungsaktivität in dieser Region zwischen den Jahren sehr variiert, besteht der dringende Bedarf, Methoden zu entwickeln, welche eine dynamische und räumlich differenzierte Einschätzung der Hangrutschungsgefährdung auf regionaler Ebene erlauben. Aufgrund der Größe des Untersuchungsgebietes von über 12.000 km2 sind für die Entwicklung dieser Methoden satellitengestützte Fernerkundungsdaten besonders geeignet, da sie die einzige räumlich kontinuierliche und zeitlich wiederholbare Informationsbasis für die gesamte Region darstellen. In diesem Paper wird gezeigt, wie GIS- und Fernerkundungsverfahren für die Erfassung, Überprüfung und Homogenisierung heterogener Hangrutschungsdaten aus mehreren Quellen verwendet werden, um eine multitemporale Inventarisierung von Hangrutschungen zu ermöglichen. Besonderer Wert wird dabei auf die räumliche Konsistenz der Daten, die Dokumentation des zeitlichen Auftretens und die Erfassung von wiederholten Hangrutschungsereignissen innerhalb desselben Hangs gelegt. Um die multitemporale Hangrutschungsinventarisierung zu unterstützen, ist ein QGIS-basiertes Informationssystem entwickelt worden, welches mit angepassten Datenabfragen und räumlichen Analysen zur Ableitung von Hangrutschungsattributen beiträgt. Das Informations-system beinhaltet zusätzliche Geobasisdaten wie ein räumlich konsistentes multitemporales Archiv von Satellitenbildern und topographische Karten.
A.]. All rights reserved. Readers may make verbatim copies of this document for non-commercial pu... more A.]. All rights reserved. Readers may make verbatim copies of this document for non-commercial purposes by any means, provided that this copyright notice appears on all such copies.
In Southern Kyrgyzstan, landslides regularly endanger human lives and infrastructure. They are a ... more In Southern Kyrgyzstan, landslides regularly endanger human lives and infrastructure. They are a very dynamic phenomenon with variations in the process activity between years. This creates a need for the development of new methods of dynamic and spatially differentiated landslide hazard assessment at a regional scale. Because of the large size of the study area (over 12 000 km²), remote sensing data are a valuable and reliable source of detailed and consistent spatial information for landslide investigations in Southern Kyrgyzstan. The paper demonstrates how remote sensing and GIS techniques are used at multiple stages of landslide hazard assessment for the acquisition, verification and homogenization of information on landslides, predisposing and triggering factors.
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Papers by Sigrid Roessner