This web page by Antonio Tejada describes height field ray casting tests done completely on a 3DLabs P10 graphics processor in a single pass. The tests include vanilla raycasting, shadows and an interesting hierarchical height field approach. The work was done two years ago using a prototype implementation of the OpenGL Shading Language. (One pass height field ray casting on a VPU.)

This IEEE TVCG paper by Kalaiah and Varshney describes a technique for computing a local normal vector field distribution on the GPU. This distribution is determined using a Taylor series expansion derived from the local surface curvatures. Kalaiah and Varshney apply this technique to per-pixel illumination computation for point-based rendering. This method of approximating local vector distributions may also be used in physically-based modeling, collision response, and ray tracing for a variety of application domains including architectural, mechanical, and molecular CAD. Results show that for similar rendering quality, this approach needs fewer primitives as compared to simple splatting-based approaches, resulting in a significant rendering speedup. (Modeling and Rendering Points with Local Geometry. Aravind Kalaiah and Amitabh Varshney. IEEE TVCG. Vol. 9, No. 1, January 2003, pp 30-42)

This Vis03 paper by Krüger and Westermann addresses the integration of early ray termination and empty-space skipping into texture based volume rendering on graphical processing units (GPU). Therefore, volume ray-casting on programmable graphics hardware is described as an alternative to object-order approaches. The early z-test is exploited to terminate fragment processing once sufficient opacity has been accumulated, and to skip empty space along the rays of sight. Performance gains up to a factor of 3 for typical renditions of volumetric data sets on the ATI 9700 graphics card are demonstrated. (Acceleration Techniques for GPU-based Volume Rendering To appear in IEEE Visualization 2003)

This EGSR 2003 paper by Goodnight et al. demonstrates the implementation of a real-time tone mapping algorithm on programmable graphics hardware. This allows interactive applications to achieve higher levels of realism by rendering with physically based, unclamped lighting values and high dynamic range texture maps. (Interactive Time-Dependent Tone Mapping Using Programmable Graphics Hardware. In Proceedings of Eurographics Symposium on Rendering 2003.)