There's another great application of spherical harmonics in (non-real-time) lighting, used by Weta for Avatar. Instead of precomputing the terms for a particul

There's another great application of spherical harmonics in (non-real-time) lighting, used by Weta for Avatar. Instead of precomputing the terms for a particular lighting setup as above, they use SH to store an environment map for every point on an object, including the effect of occluding geometry. This is independent of the camera and light positions. At render time it's then cheap to rotate the environment or move the lights, and still get correctly occluded diffuse lighting. They won a technical Academy award for it. Easy-ish overview: https://www.fxguide.com/featured/the-science-of-spherical-harmonics-at-weta-digital/ https://www.fxguide.com/featured/the-science-of-spherical-ha... SIGGRAPH 2010 paper, focusing more on the creation of the SH cache than it's use: http://dbonline.igroupnet.com/ACM.FT/1780000/1778774/037-pantaleoni.pdf http://dbonline.igroupnet.com/ACM.FT/1780000/1778774/037-pan... Slides about same: http://wwwcg.in.tum.de/fileadmin/user_upload/Lehrstuehle/Lehrstuhl_XV/Teaching/SS13/BaMaSeminar/Eckert_Slides.pdf http://wwwcg.in.tum.de/fileadmin/user_upload/Lehrstuehle/Leh...