Capabilities:

• Digital Elevation Models (DEM) at accelerated rates and at a competitive cost
• Both high (10 meter) and low (30 meter) resolution DEM data
• Drainage-enforced DEM produced with high-resolution hydrographic vector data
• Available through GDM's Innovative Partnership (IP) with the USGS National Mapping Division

GDM has a Commercial Of The Shelf (COTS) solution for building accurate DEM data consistent with USGS National Map Accuracy specifications. All DEM data produced under the GDM production process is validated with though USGS provided validation software modules.

Technical Approach:

• Develop realistic representation of the earth's surface using numerous algorithms that best define changes in topography and drainage patterns.
• Input vectors and point data include hypsography (contours), hydrography, spot elevation, ridge and supplemental drain data. Additional data layers can also be used to help produce and control model development.
• Special attributes are added to the source vector files to control complex topography and its behaviors during model development.

Production capability has been upgraded to provide for drainage enforcement of the DEM. Specific steps are taken to assure flow is not interrupted within a watershed and unnecessary sinks have been eliminated.

GDM is committed to the continued development of quality DEM data. Through in-house research, GDM is making the production of large volume DEMs more efficient by utilizing both traditional modeling techniques and new, emerging technologies. Integral to this process is production-related quality control and assurance. The GDM quality control process corrects for anomalies that often plague DEMs, such as abrupt breaks in elevation profiles, terracing, false depressions and sinks. These anomalies are corrected with both automatic and interactive procedures.