Shadows and complex lighting are an essential part of realistic rendering, however they can be computationally expensive (such as path tracing shadows). Therefore image-based methods, Shadow and Environment Mapping (See figure 1), are used to accelerate and approximate these effects in interactive real-time rendering. Shadow mapping is an old technique [Williams 78], but very widely used and developed with many extensions and implementations (Renderman). Environment mapping is also a very old technique [Blinn and Newell 76], but has only seen more use and development in recent times due to previous hardware limitations.
[1]
Ira Kemelmacher-Shlizerman,et al.
Photometric Stereo with General, Unknown Lighting
,
2006,
International Journal of Computer Vision.
[2]
Pat Hanrahan,et al.
A signal-processing framework for reflection
,
2004,
ACM Trans. Graph..
[3]
Lance Williams,et al.
Casting curved shadows on curved surfaces
,
1978,
SIGGRAPH.
[4]
James F. Blinn,et al.
Texture and reflection in computer generated images
,
1976,
CACM.
[5]
David Salesin,et al.
Rendering antialiased shadows with depth maps
,
1987,
SIGGRAPH.