Abstract: A system using a ray-tracing algorithm and a hierarchy of volume elements (called voxels) to process only the visible surfaces in a field of view. In this arrangement, a dense, three-dimensional voxel data base is developed from the objects, their shadows and other features recorded, for example, in two-dimensional aerial photography. The rays are grouped into subimages and the subimages are executed as parallel tasks on a multiple instruction stream and multiple data stream computer (MIMD). The use of a three-dimensional voxel data base formed by combining three-dimensional digital terrain elevation data with two-dimensional plan view and oblique view aerial photography permits the development of a realistic and cost-effective data base. Hidden surfaces are not processed. By processing only visible surfaces, displays can now be produced depicting the nap-of-the-earth as seen in low flight of aircraft or as viewed from ground vehicles.