ERIM has developed and refined procedures for preparing Digital Elevation Models from scanned full-color topographic map sources. The process is technologically challenging -- involving raster scanning, image processing, semi-automated feature extraction, raster-to-vector conversion, coordinate transformation, and surface generation technologies. The resulting system, DTED/Topo, supports the development of DMA DTED-formatted DEM's from hardcopy topographic maps in a production environment. A main menu guides the user through the DEM development process and includes appropriately sequenced quality control steps. An underlying database tracks various interim data products from the original scanned map through the creation of the final DTED cell, recording data creation and quality control information. As a final step, an accuracy assessment, compliant with DMA standard procedures, is conducted. The resulting DEMs may be converted from ArcInfos GRID structure to either a generic raster image format (.BIL) or to DMAs DTED format.
For regions of the world where no suitable DEM exists, hardcopy topographic maps can be used to cost-effectively develop a digital elevation database. Terrain features generally do not change, so virtually any vintage topographic map is a potential candidate. DTED/Topo provides a production environment for efficiently producing DEMs from scanned map sources -- exploiting information previously created and mapped at only a fraction of the original map preparation cost. It achieves a significant reduction in labor over manual digitizing methods. Through integrated QC steps, operator errors can be detected and corrected -- or even eliminated -- early in the DEM production process. Developed with AMLs, DTED/Topo integrates into existing workstation ArcInfo settings.
