The Digital Surface Model (DSM) products represent the first reflective surface as illuminated by the radar. Accuracy statements are based on areas of moderate terrain. Diminished accuracies are to be expected in areas of extreme terrain and dense vegetation.
The DSM data for 7.5-minute by 7.5-minute units correspond to the USGS 1:24,000 scale topographic quadrangle map series for areas in the United States and throughout the world. Each 7.5-minute by 7.5-minute DSM is comprised of elevations at 5 meter postings. Each tile provides full coverage with overlap into adjacent tiles. Data for locations above 56 degrees North/South are licensed in 7.5-minute by 15-minute tiles.