Shadow maps for real terrain

Abstract

The use of digital elevation models, which represent the surface of the earth by a matrix of heights, has proved an ideal introductory topic for developing both the matrix-handling and computational skills of undergraduate mathematicians. This article looks at the solving of an easily understandable, but not necessarily simple problem: given a particular date, time and terrain, and within the software skills available to first-year students via a computer algebra system, produce a map which can show those parts of the terrain which lie in shadow.