Pixel color accumulation in a ray tracing image processing system

An image processing system comprising:

• a memory cache;
• a first processing element configured to issue an original ray into a three dimensional scene through a pixel, traverse a spatial index with the original ray until a first leaf node is reached;
• and
• a second processing element configured to receive, from the first processing element, information defining the original ray and the first leaf node, determine a first color contribution to the pixel based on a color of a first primitive intersected by the original ray, determine a first reflective or refractive scaling factor of color contribution based on the first primitive, issue a secondary ray based on the intersection of the original ray and the first primitive, and associate the first reflective or refractive scaling factor of color contribution with the secondary ray;
• wherein the first processing element is further configured to traverse the spatial index with the secondary ray until a second leaf node is reached;
• wherein the second processing element is further configured to:
• receive, from the first processing element, information defining the secondary ray and the second leaf node;
• determine a second color contribution to the pixel based on a color of a second primitive intersected by the secondary ray and the first reflective or refractive scaling factor, and not based on a second reflective or refractive scaling factor of the second primitive;
• determine a third reflective or refractive scaling factor of color contribution based on the first reflective or refractive scaling factor and the second reflective or refractive scaling factor, and not based on a reflective or refractive scaling factor of the third primitive:
• issue a further secondary ray based on the intersection of the secondary ray and the second primitive;
• and
• associate the third reflective or refractive scaling factor of color contribution with the further secondary ray.

A non-transitory computer-readable medium containing a program which, when executed, performs operations comprising:

• issuing a primary ray into a three dimensional scene through a pixel;
• determining an initial color value for the pixel based on a color value of a first primitive intersected by the primary ray;
• issuing a secondary ray into the scene from the primitive intersected by the primary ray;
• updating the color value for the pixel based on a color value of a second primitive intersected by the secondary ray and a reflective or refractive scaling factor having a predetermined association with the first primitive intersected by the primary ray, and not based on a reflective or refractive scaling factor of the second primitive;
• issuing a further secondary ray into the scene from the primitive intersected by the secondary ray;
• and
• updating the color value for the pixel based on a color value of a third primitive intersected by the further secondary ray and a second reflective or refractive scaling factor based on the first primitive and the second primitive, and not based on a reflective or refractive scaling factor of the third primitive.