Hello! I've been reading this page recently,

http://kayru.org/articles/dssdo/

The idea is quite straightforward and it's quite easy to replace existing ssao implementation. However, one thing really confused me was that the author said, 'the local occlusion function can be reconstructed by the dot product of occlusion coefficients and light vector'?

AFAIK, if calculating diffuse lighting, we also need to project incoming light to the shpere, then do a dot product between both coefficients.

Just wondering why a simple dot product between occlusion coefficient and light vector is sufficient in this case. Anyone can help explain the math behind it? Or is there any paper describing the detail/trick?

Thanks.

**Edited by bybw, 27 June 2013 - 03:24 PM.**