Digital Elevation Models to Support Desert Warfare

Abstract

Digital elevation models (DEMs) provide a fundamental resource for terrain analysis and military mission planning. Recent developments have changed the quality of the DEMs available worldwide. The Shuttle Radar Topography Mission (SRTM) flew in 2000 and created DEMs with resolutions of 1ʺ (~ 30 m) for the US military and 3ʺ (~ 90 m) freely available for the general public. The SRTM covered all the earth except for high latitude regions. For the rest of the world its major limitations are the data voids in regions of high relief. Less publicized are the voids in dry desert sand, which account for a larger fraction of the voids than those in high mountains. In contrast to the active radar used for SRTM, which worked day/night and through clouds, the more recent ASTER GDEM used near infrared energy which only worked in daylight and could not penetrate clouds. Development of the ASTER GDEM required years of data collection for relatively complete coverage. Significant anomalies were present in version 1, in large part due to undetected clouds. Version 2 of GDEM offered improvements, but still has anomalies, and the desert regions have the largest concentration of poorly correlated GDEM and SRTM. SRTM or GDEM can provide terrain data for large area, small scale military operations. For very large scale operations, interferometric synthetic aperture radar (IFSAR) DEMs provide point spacings of 3–5 m and LiDAR provides spacings of about 1 m. These data sets are much less widely and freely available, in part because of the huge volume of data: SRTM 3ʺ requires 35 GB for global coverage, ASTER GDEM about 561 GB, and 1 m LiDAR will require about 1000 TB for full coverage. LiDAR point clouds offer additional visualization and analysis capabilities compared to traditional grids.