Method of and apparatus for constructing an image of a notional scene by a process of ray tracing
First Claim
1. A method of constructing an image of a notional scene, containing a plurality of objects, as viewed from one of a plurality of possible viewing positions and illuminated in a known manner, from information on the co-ordinates of the set of surfaces defining the objects, on the optical characteristics of all the points on those surfaces and on the particular illumination, which information is stored in a computer memory, the method comprising the steps of:
- A. Allocating the surfaces into a plurality of subsets each containing one or more surfaces;
B. Projecting from the viewing position a plurality of straight line paths and storing data describing all said paths;
C. For one of the subsets, determining which, if any, of the straight line paths intersect at least one of the surfaces in that subset, or a zone of illumination and determining the co-ordinates of said intersections;
D. Repeating step C above for the other subset or for each other subset in turn;
E. Determining, for each path which intersects a surface or zone of illumination, the nearest intersection to the viewing position and storing same with data on the object surface or zone of illumination at that intersection;
F. Determining, for each nearest intersection the light which will pass along the path to the viewing position from said intersection and storing same as light intensity and position data; and
G. Reading out the stored light intensity and position data, to produce a picture signal for a visual display.
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Accused Products
Abstract
A ray tracing method for construction an image of a notional scene from data concerning a plurality of objects in the scene and the illumination of the scene, involves allocating surfaces of objects in the scene into a plurality of subsets, projecting from a notional viewing position a plurality of straight line paths and storing data for all said paths, determining which, if any, of those straight line paths intersect any surface in a selected subset or a zone of illumination, and repeating that step for all the other subsets until all the paths have been tested for intersections against all surfaces in the scene. The method also determines, for each path, which intersection is nearest the viewing position and stores data on the co-ordinates for that intersection and on the surface of the object or zone of illumination at that intersection. The intensity in colour of light which will pass along the path through the notional viewing position from that intersection is then calculated and stored, and the stored intensity and/or colour is then used to produce a picture signal for a visual display. A plurality of paths are tested for intersections against a given subset of surfaces before the paths are considered in relation to other subsets, thereby reducing the number of times the subsets have to be called up from the database. The method can be conducted on apparatus which uses parallel ray processors.
169 Citations
21 Claims
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1. A method of constructing an image of a notional scene, containing a plurality of objects, as viewed from one of a plurality of possible viewing positions and illuminated in a known manner, from information on the co-ordinates of the set of surfaces defining the objects, on the optical characteristics of all the points on those surfaces and on the particular illumination, which information is stored in a computer memory, the method comprising the steps of:
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A. Allocating the surfaces into a plurality of subsets each containing one or more surfaces; B. Projecting from the viewing position a plurality of straight line paths and storing data describing all said paths; C. For one of the subsets, determining which, if any, of the straight line paths intersect at least one of the surfaces in that subset, or a zone of illumination and determining the co-ordinates of said intersections; D. Repeating step C above for the other subset or for each other subset in turn; E. Determining, for each path which intersects a surface or zone of illumination, the nearest intersection to the viewing position and storing same with data on the object surface or zone of illumination at that intersection; F. Determining, for each nearest intersection the light which will pass along the path to the viewing position from said intersection and storing same as light intensity and position data; and G. Reading out the stored light intensity and position data, to produce a picture signal for a visual display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 20)
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8. Apparatus for constructing an image of a notional scene containing a plurality of objects as viewed from one of a plurality of possible viewing positions, the apparatus comprising:
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memory means on which information on the co-ordinates of the surfaces of the objects, the optical characteristics of all the points on those surfaces and on the illumination for the scene is stored, the co-ordinate data being arranged in subsets each containing data for one or more object surfaces; ray tracing means for projecting from the viewing position a plurality of straight line paths for determining which, if any, of the paths intersect a surface of each object or a zone of illumination, and for selecting the intersections of each path closest to the viewing position; calculating means for determining, from the data on the object surfaces at said intersections and on the illumination of the scene, at least the intensity of the light which will pass along each said path to the viewing position; and output means for generating a picture signal, representative of said intensities, for display on a visual display, wherein all the intersections for a first subset of one or more object surfaces selected by the ray tracing means are determined before the intersections with the or each other subset, so that the intersections are determined in respect of each subset in turn. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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21. A method of constructing an image of a notional scene, containing a plurality of objects, as viewed from one of a plurality of possible viewing positions and illuminated in a known manner, from information on the co-ordinates of the set of surfaces defining the objects, on the optical characteristics of all the points on those surfaces and on the particular illumination, which information is stored in a computer memory, the method comprising the steps of
A. allocating the surfaces into a plurality of subsets each containing a respective group of surfaces; -
B. projecting from the viewing position a plurality of straight line paths and storing data describing all said paths; C. for one of the subsets, determining which, if any, of the straight line paths intersect at least one of the surfaces in that subset, or a zone of illumination and determining the co-ordinates of said intersections; D. repeating step C above for the other subset or for each other subset in turn; E. determining, for each path which intersects a surface or zone of illumination, the nearest intersection to the viewing position and storing same with data on the object surface or zone of illumination at that intersection; F. determining, for each nearest intersection the light which will pass along the path to the viewing position from said intersection and storing same as light intensity and position data; and G. reading out the stored light intensity and position data, to produce a picture signal for a visual display, wherein all the paths are generated before intersections with the surfaces are determined, all the paths are tested for intersections with all the surfaces in a given subset before any one of the paths is tested for intersections with the surfaces in the next subset and wherein information on the position and shape of each surface is stored in memory means from which information on the surface is retrieved only once in order to determine intersections of that surface with all the paths.
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Specification