Abstract: A logarithmic mixer circuit in the form of a conversion circuit for mixing digital representations of logarithmic values eliminating the usual mathematical processes of determining anti-logs, summing them and then determining the logs again, the invention using addition, subtraction and a look up table. Additional utiity is obtained by the use of scaled offset representations of logarithmic values for digital processing and separate representations for zero values. Also the final output values are limited to the range of the inputs in anticipation of further processing.

Abstract: A digital image generator (DIG) that realizes a modular architecture. The DIG employes a geometric processor that processes a plurality of prioritized faces which comprise an image to be displayed. The faces, in turn, comprise a plurality of picture elements (pixels) which are processed according to whether a skip over logic device determines that the pixels are visible and not occulted. Pixels that are in fact visible are processed, in part, by a Bed of Nails (BON) device-spatial filter device combination. This combination provides quantization of a visible pixel at a subpixel resolution level. Pixels that have been so processed are stored in a frame buffer memory for input to a display.

Abstract: A flight simulator combines flight data and polygon face terrain data to provide a CRT display at each window of the simulated aircraft. The data base specifies the relative position of each vertex of each polygon face therein. Only those terrain faces currently appearing within the pyramid of vision defined by the pilots eye and the edges of the pilots window need be displayed at any given time. As the orientation of the pyramid of vision changes in response to flight data, the displayed faces are correspondingly displaced, eventually moving out of the pyramid of vision. Faces which are currently not visible (outside the pyramid of vision) are clipped from the data flow. In addition, faces which are only partially outside of pyramid of vision are reconstructed to eliminate the outside portion. Window coordinates are generated defining the distance between each vertex and each of the boundary planes forming the pyramid of vision.