Terrain visualization by ray tracing a conical height field transformation

摘要

A parametric height-field ray-tracing process facilitates the construction of a perspective view display for terrain visualization by employing a map providing data in the form of a height field and wherein, prior to initiation of a ray tracing program, the set of voxels of the height field is transformed into a set of cones of empty space opening upwardly wherein the location of the vertex of each cone is near the height of the corresponding voxel. Each cone opens to a maximum cone angle which avoids intersection between the surface of the cone and vertical perturbations of the terrain such as buildings or hills. Ray tracing is conducted by calculating intercepts of a ray with surfaces of a succession of cones wherein the next cone of the succession is obtained by selecting the cone having a vertex beneath the location of the previous intersection. This procedure reduces greatly the number of computations required for a ray-tracing program.