Adaptive sampling of intersectable models exploiting image and object-space coherence

In ray casting interactivity is limited by intersection tests with the underlying surface. Depending on the surface, intersection tests can be very expensive operations. To achieve interactivity in ray casting in spite of that fact, a framework is implemented that accommodates the amount of intersection tests on the sampling grid in image space according to the surface variation. The shape is approximated by bilinear patches that represent several samples in a rectangular area that can be interpolated, illuminated and tested for occlusion using ordinary graphics hardware, leaving more CPU time for intersection tests. Object-space coherence is exploited by reusing these bilinear patches in consecutive views.