Patent Document ID: 4865423
Application ID: 07215007
Patent Status: 1

Claim One:
1. In a system for generating images where processing means, display means, and storage means are provided, a method for generating images of at least one object to be projected on a projective plane, on a screen of said display means which corresponds to the projective plane, using a ray-tracing method, which comprises the following steps: (a) (a1) supposing a viewpoint, supposing a ray which passes the viewpoint and a point on the projective plane which corresponds to a pel for each pel on the screen and searching an intersection where the ray meets a surface of said at least one object which is nearest to the viewpoint for each supposed ray, and (a2) if the desired point is obtained, repeating a step at least once which comprises supposing at least one of the reflected ray and the transmitted ray which starts from the intersection obtained in the preceding search and searching an intersection where the supposed ray meets a surface of said at least one object which is nearest to the intersection obtained in the preceding search, and (b) with respect to the supposed ray which passes said viewpoint and a point on said projective plane which corresponds to a pel on the said screen, if at least one intersection is obtained through the search as described in (a) which begins with said ray, determining optical information to be assigned to the pel associated with said ray in consideration of the attribute of said at least one intersection, if no intersection is obtained through the search as described in (a), assigning optical information which corresponds a background of said at least one object to the pel associated with the said ray, characterized by (I) prior to the step (a1), (i) defining a space region which contains said at least one object to be displayed, (ii) dividing said space region into a plurality of cells, (iii) determining whether the cell contains at least one surface of said at least one object or not for each cell, and if the cell contains the said at least one surface, registering the cell in a table provided in said storage means, (II) in the step (a1), determining whether the ray intersects said space region or not by calculation prior to performing the calculation for an intersection for each supposed ray, and ending the search for an intersection for the ray which doesn't intersect said space region, under a decision that the ray intersects no surface of said at least one object, (III) in the steps (a1) and (a2), identifying the cell which the ray intersects for each ray that intersects said space region by calculation, collating the identified cell with said table, and if the identified cell is found to contain the surface of said at least one object, searching an intersection where the ray meets the surface in the cell in a numerically analytic way which uses sampling, and if the identified cell is found to contain no surface of the said at least one object, ending the search for an intersection where the ray meets the surface in the cell, under a decision that the ray intersects no surface of said at least one object there.