Hughes Aircraft Company

Myron L Nack

Norton L Moise

Chao Yang

Robert J McMillen

Andrew Rosman

Gary N Landis

Thomas O Ellis

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. The approach employed here is a highly-parallel data processing system solution to the nap-of-the-earth flight simulation through a high level of detail data base. The components of the system are the display algorithm and data structure, the software which implements the algorithm and data structure and creates the data base, and the hardware which executes the software. The algorithm processes only visible surfaces so that the occulting overload management problem is eliminated at the design level. The algorithm decomposes the image into subimages and processes the subimages independently.

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Los Alamitos, CA, United States of America

Myron L Nack