"ft-SSIBL for “Screen Space Image Base Lighting” is based on a topic I covered in a previous post about Roy Stelzer’s “2.5D Relighting inside of Nuke”. In this shader I tried to reproduced a few approach found in his Nuke script. So with a Normal pass (object or world), you will be able to do some relighting with a HDR map. The shader won’t compute the 9 coefficients (spherical harmonics) needed for you as describe in this paper: http://graphics.stanford.edu/papers/envmap. But don’t worry I’ll do a quick tutorial soon on how to find those coefficients with your own lightprobe (aka angular map).
The default values are from the Grace Cathedral, San Francisco Lightprobe by Paul Debevec."
Here's the intro video:
Update: Francois added Light probe to 9 spherical harmonics coefficients, a video that shows you how to convert your own light probe (angular map, mirror ball, HDR map, ... ) into the 9 coefficients (spherical harmonics) needed for his ft-SSIBL shader.