US Patent 7499053 Real-time precision ray tracing

Systems and techniques are described for ray tracing and for the efficient construction of acceleration data structures required for fast ray tracing. A computer graphics system generates, for each pixel in an image, a pixel value that is representative of a point in a scene as recorded on an image plane of a simulated camera. The computer graphics system is configured to generate the pixel value for an image using a selected ray-tracing methodology. The selected ray-tracing methodology includes the use of a ray tree that includes at least one ray shot from the pixel into a scene along a selected direction. The ray-tracing methodology further includes calculating the intersections of rays and surfaces in the scene. An axis-aligned bounding box is defined that contains, for a given ray, the point of intersection of the ray and surface nearest the origin of the ray. The bounding box is iteratively refined until a predetermined termination criterion has been met.