High Altitude Lidar to Enhance Geosar System Performance

EarthData Technologies has performed a research and development project to investigate the possibilities of a comounted LIDAR system to enhance the performance of the Geographic Synthetic Aperture Radar (GeoSAR) system. The LIDAR system could provide precise ground control points that can be used in the mosaick process and it could add valuable information about tree canopy structures to the process of merging the X-band and P-band data, which would improve the Digital Elevation Model (DEM) accuracy of the GeoSAR system. Therefore, an off-the-shelf ALS40 unit manufactured by Leica Geosystems was tested in profiling mode at 10 km above terrain. The LIDAR profiler was capable of consistently producing range measurements from that altitude with a vertical precision of 26 cm (1 sigma), after applying a special bore sight method that had been developed by EarthData Technologies. Although the high altitude LIDAR system was not able to penetrate through clouds, it did penetrate through vegetation to map the underlying ground level at the same rate as a LIDAR system operating from lower altitudes. Finally, a method was developed to approximate the “thickness” of the vegetation by waveform simulation from a multiple return system. The results of the high altitude LIDAR tests are presented in this paper.