First experiments in viewshed uncertainty : the accuracy of the viewshed area

Abstract

Digital elevation models (DEMS) are computer representations of a portion of the land surface. The elevations recorded in the DEM are not, however, without error, and the United States Geological Survey (USGS) publish a root- mean-squared error (RMSE) for each Dm. The research reported here examines how that error propagates into derivative products resulting from geographic information system (GIS)-type operations. One product from a DEM, the focus of this paper, is the viewshed. The viewshed is the area observable from a viewing location versus that which is invisible. In this research repeated error fields with varying parameters are added to the original DEM, and the viewshed is determined in the resulting noisy DEM. Results show that the area of the viewshed calculated in the original DEM may significantly overestimate the viewshed area.