| 摘要 |
A computer graphics system generates pixel values for pixels in an image of objects in a scene, using strictly-deterministic low-discrepancy sequences, illustratively Halton sequences, as sample points for evaluating integrals which are used to simulate a number of computer graphic techniques, including: (1) soft shadows generated for scenes illuminated by a light source having a finite extent, such as a disk, as opposed to a point light source; (2) simulation of depth of field; (3) motion blur; (4) jittering. The computer graphics system uses the low-discrepancy sequence: (1) in connection with soft shadows, to generate sample points over the extent of the light source illuminating the scene; (2) in connection with simulation of depth of field, to generate sample points over the area of the lens between the scene and the image; (3) in connection with motion blur, to generate sample points over a time interval over which motion blur is to be simulated for moving objects in the scene; and (4) in connection with jittering, to generate jittered sample points over an image or a plurality of contiguous pixels. Unlike the random numbers used in connection with the Monte Carlo technique, the low discrepancy sequences ensure that the sample points are evenly distributed over a respective region or time interval, thereby reducing error in the image which can result from clumping of such sample points which can occur in the Monte Carlo technique. In particular, the invention facilitates the generation of images of improved quality when using the same number of sample points at the same computational cost as in the Monte Carlo technique.
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