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Summary of Proposal LAN3095

TitleDetecting informal settlements inside mega-cities by their structural characteristics in high-resolution SAR data
Investigator Wendleder, Anna - German Aerospace Center , German Remote Sensing Data Center
Team Member
Dr. Wurm, Michael - German Aerospace Center (DLR), German Remote Sensing Data Center (DFD)
Dr. Taubenböck, Hannes - German Aerospace Center (DLR), German Remote Sensing Data Center (DFD)
Prof. Dr.- Ing. Schmitt, Andreas - Hochschule München, Fakultät für Geoinformation
SummaryThe detection of informal settlements is essential for the assessment of today’s mega-cities. While formal settlements in general are well planned and documented with respect to geographical population distribution, necessary infrastructure and so on, most informal settlements grow without any administrative control. Thus, no reliable or comparable information on their extent, their population, or their dynamics can be gathered except for remote sensing. Regarding optical sensors the distinction of formal from informal settlements seems to be quite easy visually. Unfortunately, the visual interpretation is much too expensive for large scale or even global applications. In contrast to that, the automated detection still is very challenging because both types of settlements show similar spectral behavior. The only difference can be found in the shape and the spatial arrangement of the objects: larger clearly structured objects for formal buildings, smaller mostly unstructured objects in informal settlements. At this point, the idea arises to employ a sensor type sensitive especially for geometric structures in the imaged land scape: Polarimetric Synthetic Aperture Radar. This type of active sensor (independent of weather or natural illumination) enables the identification of different backscatter mechanisms by the help of multi-polarized imaging. The varying shapes of objects in the illuminated scene naturally cause different polarimetric behavior which is characteristic for the structure of the underlying settlement. This already has been proven for dual-polarized spotlight data in preliminary studies. The data retrieved vie this proposal shall be used to prove the transferability from one test case to mega-cities worldwide. Secondary, the synergistic effects of combining multi-frequent and multi-polarized SAR data shall be investigated by joining the TerraSAR-X acquitisitzions with RADARSAT-2 acquisitions from an ESA TPM proposal. Two departments of the German Remote Sensing Data Center (DFD) in Oberpfaffenhofen are working together on this topic: The “Land surface” department represented by Dr. Andreas Schmitt is providing and further developing the (pre-) processing routines via its Multi-SAR approach. The “Geo-risks and Civil Security” department represented by Dr. Michael Wurm and Dr. Hannes Taubenböck analyzes the value-added Multi-SAR output data in view of the detection and characterization of informal settlements. Due to the long experience in the remote sensing of mega-cities sufficient reference data sets are available within the working group to validate the observation. Contemporaneously, new TerraSAR-X data can be acquired along with the RADARSAT-2 images via an existing science proposal. The ambitious goal is to develop algorithms that enable the automated large-scale detection of informal settlements in order to derive their current extent as well as their future development. This research project is funded by the German Aerospace Center (DLR). Any valuable scientific results will be published in remote sensing journals and additionally presented on appropriate national and international conferences.

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