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Summary of Proposal MTH1462

TitleChange detection in urban area by use of radargrammetry
Investigator Dubois, Clémence - KIT - Karlsruhe Institute of Technology, IPF - Institute of Photogrammetry and Remote Sensing
Team MemberNo team members defined
SummaryThe basic idea of our proposal is to detect changes in buildings shape and height after an event such as a natural disaster by use of radargrammetry. As such an event is not predictable, the chosen test site is located in the agglomeration area of Paris, France, where building demolitions are planned within the framework of an urban reconversion project. Contacts on site have already been established in order to facilitate the ground truth data acquisition and to follow up-to-date the evolution of the demolitions. In this project, two different data sets will be used: interferometric data for the pre-event analysis, and radargrammetric data for the post-event analysis. This choice results from the data coherency before and after the event, a good signal coherency being mandatory for using interferometric SAR. A TanDEM-X proposal has already been submitted for the pre-event data. For the post-event analysis and change detection approach, which is the subject of this proposal, high resolution TerraSAR-X data are required, in order to examine the potential of this acquisition mode for urban areas, where a high level of detail is mandatory. Different illumination angles, as well as combination between ascending and descending orbits, will be tested, allowing us to determine which radargrammetric configuration is the most appropriate for accurate height determination and change detection. The change detection approach will start with the extraction of building features in both interferometric and radargrammetric dataset (lines and surfaces), allowed by the high quality of these data. By use of these features and of potentially underlying information about the original building footprint, a filtering will be performed in both data sets independently, allowing to smooth the building signatures for a better interpretation. The filtering approach already exists for interferometric data and has to be adapted to radargrammetric data, which present other statistics. Then, we will extract new features in the filtered data, which can be more relevant for change detection, such as rubbled textures and broken lines. Using these features, a change detection approach will be implemented in order to determinate the changes that occurred at building location. The final implemented system should deliver a classification of the buildings, showing which ones are damaged and which ones are still standing, permitting the rescuers to act rapidly in crisis circumstances. This approach will be validated through several quality assessments. For the pre-demolition stage, a first field campaign will take place before the building destructions, in order to determinate with accuracy the building heights, and archive lidar data will be used complementary. After the building demolitions, a second field campaign will take place in order to evaluate and measure the damages, and an optical satellite image will support the results. Both will serve as reference for the quality measures of our change detection approach. Eventually, interferometric pairs of TerraSAR-X are requested for the post-event analysis, in order to assess the classification results obtained with radargrammetry in comparison with those obtained with the typical interferometric data analysis. This project is funded by the Karlsruhe Institute of Technology (KIT) in the framework of a Feasibility study of Young Scientists (FYS). FYS gives a financial independency to young scientist to pursue an idea that they came up with during their diploma or doctoral thesis.

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