Visualisation of topographic data using video animation

A wide range of software tools have been developed for visualising three-dimensional range data of topographic surfaces. Digital Elevation Models (DEMs), derived from photogrammetric measurements and from digitised contour maps are here used for illustration. To increase our understanding of the information content in DEMs in isolation or in combination with remotelysensed images and to facilitate the quality assesment of automated terrain extraction techniques a number of tools have been developed for displaying perspective views of time sequences of landscapes with a variety of different surface shading models. We consider a variety of shading models from the texture mapping of a satellite image over a DEM to attempts to represent different surface reflectances. The texture mapping problem integrates both single band (monochromatic) and multispectral (false colour of original or colourspace transformed) satellite images. Artificial shading models from simple Lambertian shading to the ray-tracing of terrains, using Bi-directional Reflectance Distribution Functions are presented.