A system for 3D error visualization and assessment of digital elevation models

A digital elevation model (DEM) can be created using a variety of interpolation or approximation methods, any of which may yield errors in the final result. We present DEMEV (DEM Error viewer), a visualization system that displays a DEM and possible errors in 3D, along with its associated contour or sparse data and/or a comparison DEM. The system incorporates several error visualizations. One method compares the test DEM to source data and highlights discrepancies (difference error) beyond a user-variable threshold. A novel, vertical cutting tool can slice the DEM to create a profile view that shows the surface of the test and comparison DEMs simultaneously, allowing the user to discern small errors between the two files in minute detail. The cutting tool is semi-transparent so that the profile is seen in the context of the 3D surface. Another novel error visualization uses height classes to display possible problems with slope in a DEM computed from contours. Other features of the system include visualizations for local curvature and slope, a display of computed statistics such as RMSE, total squared curvature, etc., in addition to typical GIS tools. The system is designed as an error-visualization tool; the above functions are displayed and readily available on the user interface. The system has been tested with USGS data files to show its efficacy.