VOID FILL OF SRTM ELEVATION DATA - PRINCIPLES, PROCESSES AND PERFORMANCE

The Shuttle Radar Topography Mission (SRTM), flown in February 2000, acquired radar data covering approximately 80 percent of the Earth's landmass. These data were used in producing a dataset of SRTM Digital Terrain Elevation Data (DTED®). Given the complex nature of IFSAR technology combined with the sensitive interaction of radar energy with the atmosphere and ground targets, the resulting dataset contained voids. During the initial finishing process of SRTM elevation data, many small voids were filled when water bodies were flattened. However, some areas of void still remained in the finished SRTM DTED®. The National Geospatial-Intelligence Agency (NGA) desires a fully populated SRTM DTED® dataset over priority areas identified by its customers. NGA has contracted the SRTM Boeing-Intermap team to develop and utilize a capability to detect and remove phase unwrapping errors and to fill SRTM DTED® voids with alternate source DEMs. This paper focuses on the principles and processes used in the void fill program by the SRTM Boeing-Intermap team. Results of a preliminary evaluation of the void filled SRTM data show the effectiveness of the implemented void fill process.