A method is presented that produces a realistic simulation of terrain using source data from the Defense Mapping Agency (DMA). Spatially compact objects are presently modeled with some success at realism. Because terrain is large in extent it exhibits special problems. These problems include: data base size and generation, masking priority, and shading.

As a technique for rendering texture in images, texture tiles meet the subjective criterion of visual acceptability. A texture tile is a digital array of stored texture information that is replicated on a surface within an image. The purpose is to give the surface a textured appearance. The repetitive pattern inherent in the tiling approach can be suppressed. A texture tile must not exhibit macropatterns to avoid this problem. Properties that the mapping algorithm must include are oriented toward controlling aliasing. The tile is stored and accessed at several different levels-of-detail. The accessing technique is based on the size of the footprint the sample projects onto the surface to be textured. Aliasing is further controlled by a combination of increased sampling per pixel and filtering. Several textured images are presented, produced by the texture tile technique. These images show the realistic effect that is added by texture tiles.