Polygon fragmentation method of distortion correction in computer image generating systems
First Claim
1. A method for pre-distorting a projection space PS video raster scene, formed of polygons having edges, to project upon a projection surface in a manner to be viewed as an undistorted VS video raster scene, having edge-defined polygons, by a viewer in viewer space VS, comprising the steps of:
- (a) assigning a regular undistorted array grid with a multiplicity of row and column lines to divide the VS raster into an array of cells;
(b) arranging a diagonal line between one pair of opposite corners of each cell in the VS raster grid array;
(c) determining in the VS raster an ordered set of all points (VS crossing points) at which each polygon edge crosses any of the grid and diagonal lines;
(d) projecting each VS crossing point back into PS projection space to determine an associated PS space projected crossing point to which that VS crossing point will be transformed;
(e) creating a line connecting each pair of projected PS crossing points which correspond to a pair of VS crossing points connected by an interconnecting polygon edge in the view raster, with a plurality of PS connecting lines thus created enclosing an associated PS raster area; and
(f) matching textural area factors in each PS raster area thus formed to similar textural area factors in the corresponding VS area.
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Accused Products
Abstract
A method for distortion correction of computer-generated textured images maps vertices and texture coefficients from viewer space to projector space, so that environmental objects are pre-distorted upon the projection raster in order to appear in their proper form and perspective when the raster is projected onto a curved surface in viewer space, and viewed therefrom. Distortion correction is carried out by utilizing a piecewise-linear approximation for smoothly, continuously and closely approximating the required pre-curvature. The viewing space raster is subdivided into a number of triangles, within each of which a linear approximation is applied to the image mapping: the raster faces are first subdivided along the lines of a rectangular grid and the face fragments falling within each rectangle are then subdivided along the grid diagonal. This produces face fragments which are small enough so that a linear approximation provides an accurate transformation of each fragment. Distortion maps, typically computed off-line and stored in a database memory, are utilized to project the edges and texture modulation gradients from view space back into projector space, so that the edges and texture patterns can now be matched at intersections of adjacent triangles, in a manner to be substantially devoid of any abrupt changes, and thus be properly pre-distorted.
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Citations
11 Claims
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1. A method for pre-distorting a projection space PS video raster scene, formed of polygons having edges, to project upon a projection surface in a manner to be viewed as an undistorted VS video raster scene, having edge-defined polygons, by a viewer in viewer space VS, comprising the steps of:
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(a) assigning a regular undistorted array grid with a multiplicity of row and column lines to divide the VS raster into an array of cells; (b) arranging a diagonal line between one pair of opposite corners of each cell in the VS raster grid array; (c) determining in the VS raster an ordered set of all points (VS crossing points) at which each polygon edge crosses any of the grid and diagonal lines; (d) projecting each VS crossing point back into PS projection space to determine an associated PS space projected crossing point to which that VS crossing point will be transformed; (e) creating a line connecting each pair of projected PS crossing points which correspond to a pair of VS crossing points connected by an interconnecting polygon edge in the view raster, with a plurality of PS connecting lines thus created enclosing an associated PS raster area; and (f) matching textural area factors in each PS raster area thus formed to similar textural area factors in the corresponding VS area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification