“Parallax searching and mesosurface shadowing” by Delgass and McGhee

Fine surface details and shadows are important visual cues for discerning relative object positions and surface contours of shadow receivers. Per-pixel displacement techniques have been presented which extend the bump mapping [Blinn 1978] mesosurface rendering technique. Parallax effects and self-occlusions have been achieved by adjusting albedo and normal map texture coordinates to account for the view direction [Policarpo et al. 2005; Donnelly 2005]. However, uncorrected application of the shadow mapping algorithm [Williams 1978] to these techniques results in flat shadows that do not conform to the shape of the displaced surface.

1. Blinn, J. F. 1978. Simulation of wrinkled surfaces. Computer Graphics (Proceedings of ACM SIGGRAPH 78) 12, 3, 286–292.]]
2. Donnelly, W. 2005. GPU Gems 2: Programming Techniques for High-Performance Graphics and General-Purpose Computation. Addison-Wesley, Boston, MA, ch. Per-pixel displacement mapping with distance functions, 123–136.]]
3. Kaneko, T., Takahei, T., Inami, M., Kawakami, N., Yanagida, Y., Maeda, T., and Tachi, S. 2001. Detailed shape representation with parallax mapping. In Proceedings of ICAT 2001, 205–208.]]
4. Policarpo, F., Oliveira, M. M., and Comba, J. L. D. 2005. Real-time relief mapping on arbitrary polygonal surfaces. In Proceedings of SI3D 2005, ACM, New York, NY, 155–162.]]
5. Williams, L. 1978. Casting curved shadows on curved surfaces. Computer Graphics (Proceedings of ACM SIGGRAPH 78) 12, 3, 270–274.]]