An efficient representation for irradiance Environment Maps

An efficient representation for irradiance Environment Maps

 

Link: http://www.eecs.berkeley.edu /~ Ravir/papers/envmap/envmap.pdf

 

This article focuses on the optimization of irradiance environment map computing.

 

1. irradiance environment map refers to a simplified processing of the Env map when an envirnment map is projected on the diffuse reflection plane.

That is, the spherical harmonics coefficient is used to save the low-frequency part, and
The storage condition is 9 coefficients.

 

The formula for calculating irradiance is:

W is the direction, L (W) is the light of environment map in this direction, and dot (n, W) is to be calculated.

 

2. For dot (n, W), the sh projection is used to obtain a pile of coefficients. This is fixed, so we can get the results. See the paper.

 

3. Now all the required things are in place. You can do lighting computing. This is a good part.

 

 

Where m is:

 

C is the sh coefficient of dot (n, W), and L is the sh coefficient of env map, so that an env map becomes an expression like vector * matrix * vector.

 

I like matrix very much, but I think it is very practical.