1. A system for determining ground height, comprising: a sensor array for producing data about a volume, said volume represented by a terrain map divided into a plurality of voxels; a plurality of terrain modeling rules, said rules including domain information for interpreting data from said sensor array, an assumption imposed by a two-dimensional, horizontal model that ground height is smoothly varying, and an assumption imposed by a two-dimensional, horizontal model that voxels having a particular classification will cluster; and an inference engine responsive to said sensor array, said terrain modeling rules, and vertical structural assumptions for inferring a classification for each voxel, said inference engine further producing a most likely ground height based on said inferred classifications.