Chris Green
ABSTRACT
In Valve's Source graphics engine, bump mapping is combined with precomputed radiosity lighting to provide realistic surface illumination. When bump map data is derived from geometric descriptions of surface detail (such as height maps), only the lighting effects caused by the surface orientation are preserved. The significant lighting cues due to lighting occlusion by surface details are lost. While it is common to use another texture channel to hold an "ambient occlusion" field, this only provides a darkening effect which is independent of the direction from which the surface is being lit and requires an auxiliary channel of data.
In this chapter, we present a modification to the Radiosity Normal Mapping system that we have described in this course in the past. This modification provides a directional occlusion function to the bump maps, which requires no additional texture memory and is faster than our previous non-shadowing solution.
- Blinn78} Blinn, J. F. 1978. Simulation of wrinkled surfaces. In SIGGRAPH '78: Proceedings of the 5th annual conference on Computer graphics and interactive techniques, ACM Press, New York, NY, USA, 286--292. Google Scholar
Digital Library
- {id97} id SOFTWARE, 1997. Quake 2.Google Scholar
- {KHD00} Kautz, J., Heidrich, W., and Daubert, K. 2000. Bump map shadows for OpenGL rendering. Tech. Rep. MPI-I-2000-4-001, Max-Planck-Institut für Informatik, Saarbrücken, Germany.Google Scholar
- {Max98} Max, N. L. 1998. Horizon mapping: shadows for bump-mapped surfaces. In The Visual Computer, 109--117.Google Scholar
- {MM05} McGuire, M., and McGuire, M. 2005. Steep parallax mapping. I3D 2005 Poster.Google Scholar
- {McTaggart04} McTaggart, G., 2004. Half-life 2 shading. GDC Direct3D Tutorial.Google Scholar
- {MMG06} Mitchell, J., McTaggart, G., and Green, C. 2006. Shading in Valve's source engine. In SIGGRAPH '06: ACM SIGGRAPH 2006 Courses, ACM Press, New York, NY, USA, 129--142. Google ScholarDigital Library
- {OS07} Oat, C., and Sander, P. V. 2007. Ambient aperture lighting. In I3D '07: Proceedings of the 2007 symposium on Interactive 3D graphics and games, ACM Press, New York, NY, USA, 61--64. Google ScholarDigital Library
- {PAC97} Peercy, M., Airey, J., and Cabral, B. 1997. Efficient bump mapping hardware. Computer Graphics 31, Annual Conference Series, 303--306. Google ScholarDigital Library
- {POC05} Policarpo, F., Oliveira, M. M., and Comba, J. L. D. 2005. Real-time relief mapping on arbitrary polygonal surfaces. In I3D '05: Proceedings of the 2005 symposium on Interactive 3D graphics and games, ACM Press, New York, NY, USA, 155--162. Google ScholarDigital Library
- {SC00} Sloan, P.-P. J., and COHEN, M. F. 2000. Interactive horizon mapping. In Proceedings of the Eurographics Workshop on Rendering Techniques 2000, Springer-Verlag, London, UK, pp. 281--286. Google ScholarDigital Library
- {Sloan00} Sloan, P.-P. 2006. Normal mapping for precomputed radiance transfer. In I3D '06: Proceedings of the 2006 symposium on Interactive 3D graphics and games, ACM Press, New York, NY, USA, pp. 23--26. Google ScholarDigital Library
- {Tatarchuk06} Tatarchuk, N. 2006. Dynamic parallax occlusion mapping with approximate soft shadows. In proceedings of AMD SIGGRAPH Symposium on Interactive 3D Graphics and Games, pp. 63--69, Redwood City, CA. Google ScholarDigital Library
- {TM98} Tomasi, C., and Manduchi, R. 1998. Bilateral filtering for gray and color images. In ICCV, 839--846. Google ScholarDigital Library
- {WBW+01} Wald, I., Benthin, C., Wagner, M., and Slusallek, P. 2001. Interactive rendering with coherent ray tracing. Computer Graphics Forum (Proceedings of EUROGRAPHICS 2001), v. 20, i. 3, pp. 153--164.Google Scholar
- Efficient self-shadowed radiosity normal mapping
Recommendations
Efficient irradiance normal mapping
I3D '10: Proceedings of the 2010 ACM SIGGRAPH symposium on Interactive 3D Graphics and GamesIrradiance normal mapping is a method to combine two popular techniques, light mapping and normal mapping, and is used in games such as Half-Life 2 or Halo 3. This combination allows using low-resolution light caching on surfaces with only a few ...
Translucent Radiosity: Efficiently CombiningDiffuse Inter-Reflection andSubsurface Scattering
It is hard to efficiently model the light transport in scenes with translucent objects for interactive applications. The inter-reflection between objects and their environments and the subsurface scattering through the materials intertwine to produce ...
Normal mapping for precomputed radiance transfer
I3D '06: Proceedings of the 2006 symposium on Interactive 3D graphics and gamesNormal mapping is a variant of bump mapping that is commonly used in computer games. It models complex surface variations by explicitly storing a surface normal in a texture map. However, it has not been used with precomputed radiance transfer (PRT), a ...
Comments