Methods and Implementation of Topographic Modeling for Thematic Mapping

Abstract

In this study we use Topographic Modeling on USGS DEM data and other digital elevation data to generate lambertian (shaded relief) surfaces, and to extract parametric information, including slope, aspect, and various convexities and curvatures. All of the parameters are calculated by fitting a quadratic surface to the digital elevation data for the entered kernel size and taking the appropriate derivatives. The kernel size can also be changed so that multi-scale topographic information can be extracted. A root mean square (RMS) error image is also generated, which indicates how well the quadratic surface fits the actual digital elevation data. Finally, the parametric information is also used to create thematic images for mapping topographic features. The raster DEMs may be also used to derive complementary topographic data sets including a topographic classification image. The raster DEM is also required for draping imagery onto topographic elevation data using the 3-D Surface View.