The Digital Terrain Model (DTM) data product was derived from the Digital Surface Model (DSM) using Intermap's proprietory algorithm.
The DTM 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 by15-minute tiles.