Shadow Techniques
See Also - Lighting Techniques, Deferred Shading , Visual Effects
Reflective Shadow Maps
http://www.vis.uni-stuttgart.de/~dachsbcn/download/rsm.pdf
Cascaded Shadow Maps
Real-time Indirect Illumination and Soft Shadows in Dynamic Scenes Using Spherical Lights
http://www.cg.tuwien.ac.at/research/publications/2008/guerrero-2008-sli/guerrero-2008-sli-paper.pdf