The accuracy of Digital Elevation Models interpolated to higher resolutions

This paper presents theoretical and practical assessments of the accuracy w ith which Digital Elevation Models (DEMs) can be interpolated to higher res olutions and demonstrates that simple bilinear or bicubic convolution is an adequate approach. It is assumed that the DEM is defined on a square grid and is free of error. In other words, this paper does not consider the ques tion of how irregularly distributed elevation measurements should optimally be resampled on to a square grid. The achievable accuracy depends principa lly on the fractal dimension of the surface and the standard deviations of the height difference between adjacent grid points in the original DEM. The accuracy depends only slightly on the factor by which the resolution of th e DEM is increased, and it is typically between 0.2 sigma and 0.6 sigma. Th e paper briefly discusses the implications of these results for one remote sensing application: the correction of Synthetic Aperture Radar imagery for the effects of terrain-induced distortion.