Intersection testing in ray tracing systems using hierarchical acceleration structures with implicitly represented nodes

An intersection testing module configured to perform intersection testing in a ray tracing system for use in rendering an image of a scene, the intersection testing module comprising:

• receiving logic configured to receive data representing at least part of a hierarchical acceleration structure, wherein the hierarchical acceleration structure comprises nodes, each of which represents a region in the scene, wherein the nodes are linked to form the hierarchical acceleration structure, wherein said received data comprises data defining the regions represented by a plurality of the nodes of the hierarchical acceleration structure, and wherein the hierarchical acceleration structure comprises an implicitly represented node, wherein data defining a region represented by the implicitly represented node is not explicitly included as part of said received data but can be inferred from said received data;
• node processing logic configured to infer, from said received data, data defining the region represented by the implicitly represented node;
• and
• one or more testing blocks configured to perform intersection testing on rays in the scene by testing the rays for intersection with regions represented by nodes of the hierarchical acceleration structure, wherein at least one of the one or more testing blocks is configured to use the inferred data to test one or more of the rays for intersection with the region represented by the implicitly represented node of the hierarchical acceleration structure.

A non-transitory computer readable storage medium having stored thereon an integrated circuit definition dataset that, when processed in an integrated circuit manufacturing system, configures the integrated circuit manufacturing system to manufacture an intersection testing module which is configured to perform intersection testing in a ray tracing system for use in rendering an image of a scene, the intersection testing module comprising:

• receiving logic configured to receive data representing at least part of a hierarchical acceleration structure, wherein the hierarchical acceleration structure comprises nodes, each of which represents a region in the scene, wherein the nodes are linked to form the hierarchical acceleration structure, wherein said received data comprises data defining the regions represented by a plurality of the nodes of the hierarchical acceleration structure, and wherein the hierarchical acceleration structure comprises an implicitly represented node, wherein data defining a region represented by the implicitly represented node is not explicitly included as part of said received data but can be inferred from said received data;
• node processing logic configured to infer, from said received data, data defining the region represented by the implicitly represented node;
• and
• one or more testing blocks configured to perform intersection testing on rays in the scene by testing the rays for intersection with regions represented by nodes of the hierarchical acceleration structure, wherein at least one of the one or more testing blocks is configured to use the inferred data to test one or more of the rays for intersection with the region represented by the implicitly represented node of the hierarchical acceleration structure.