Unsupervised high-resolution global monitoring of urban settlements

The TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement, TDM) German mission collects two global data sets of very high resolution (VHR) synthetic aperture radar (SAR) imagery between 2011 and 2013. With a spatial resolution of ~3 m, these images provide a unique data source for the delineation of built-up areas in a spatial detail that could not be addressed so far by currently existing global human settlements layers (GHSL). In this paper we present a novel unsupervised procedure that automatically detects built-up areas from TDM data at the unprecedented spatial resolution of 0.4 arcsec (~12 m). The proposed technique is being used to generate a world-wide inventory of human settlements referred to as Global Urban Footprint (GUF), which is also intended to be publicly provided at a spatial resolution of ~3.0 arcsec (i.e., ~50-75 m).