Segmentation of interferometric SAR data in urban areas

The improved quality of InSAR data suggests to utilize such data for analysis of urban areas. But, the phase information from which the height data is calculated, is often severely disturbed, depending on the signal to noise ratio. As a consequence, irregular height jumps occur even inside flat objects. In this paper we refer to investigations to stabilize and improve the InSAR height data. After preprocessing, a segmentation is carried out in the intensity and the height data. Inside the extracted segments the height data is smoothed, using the related intensity or coherence values as weights. For every segment the weighted average height is calculated. Preliminary hypotheses for buildings are identified a by significant height over surrounding ground. In a post-processing step, the intermediate results are analyzed and corrected due to a possible over- and under-segmentation. Adjacent objects with similar heights are merged and objects including shadow areas are split. The shadow areas are detected by structural image analysis in a production net environment exploiting collateral information, like sensor position and depression angle. The derived 3D information may be used for visualization or map update tasks. A test site including the airport of Frankfurt (Main) was chosen. For the visualization purpose, a 3D view of the smoothed height data is shown. The results are compared to a map and differences are depicted and discussed.