Resolvability test and projection size clipping for polygon face display

Abstract

A flight simulator combines flight data and polygon face terrain data to provide a CRT display for the windows of an aircraft trainer. The data base contains position data defining the relative position of each vertex of each polygon face, and visual data concerning the color, intensity, etc. of each face. In addition, the data base contains resolvability data for determining which faces, as displayed on the CRT, would have dimensions less than the resolvability of the display system. The resolvability standard is defined by a resolvability code (RC) and is based on the smallest resolvable angular subtense (.theta.rc). The angular subtenses (.theta. major and .theta. minor) of each face is determined by representing each face by a rectangle having a long side (S major) and a short side (S minor), and combining these side values with o (the S major unit vector) and n (the unit vector normal to the plane of S major and S minor) in a trigonometric relationship. .theta. major is compared with .theta. minor and the smaller of the two, .theta. min is compared with .theta.rc to determine whether that face is below the visibility threshold and should be dropped from further processing. ______________________________________ TABLE OF CONTENTS SECTION TITLE ______________________________________ I ABSTRACT OF THE DISCLOSURE II BACKGROUND OF THE INVENTION III SUMMARY OF THE INVENTION IV DESCRIPTION OF THE FIGURES V GENERAL DESCRIPTION OF FLIGHT SIMULATION SYSTEM 10 VI DETAILED DESCRIPTION OF INTERFACE CONTROLLER 46 AND THE DATA FORMAT VII DETAILED DESCRIPTION OF DIGITAL VISUAL COMPUTER 12 IMAGE PROCESSOR 42 VIII TRANSLATION STAGE 60 IX ROTATION STAGE 62 X CLIPPING STAGE 63 XI PROJECTION STAGE 64 XII EDGE STAGE 65 XIII CONTROL LOGIC 70 XIV DISPLAY GENERATOR 44 XV RESOLVABILITY STAGE 58 XVI CONCLUSION CLAIMS ______________________________________ SECTION II

Dependencies are inferred from the claim text.