Re: [Algorithms] More SH exponentiation questions

[Peter-Pike S. <pet...@ho...>]

I'm not really sure what you are talking about.  You might want to email John directly, I think we just computed a bunch of pairs and then built the table as a function of log magnitude (after DC isolation.)  
You could pose computing the ab texture itself as a least squares problem, and include training examples that were the result of multiple spheres (instead of just single spheres), but I don't think we did that...
Are you referring to figure 3 in the paper?  It is really just showing the OL pretty much just works as long as the magnitude is small enough...
Peter-Pike Sloan

Date: Tue, 10 Nov 2009 16:58:04 +0800
From: shu...@gm...
To: gda...@li...
Subject: [Algorithms] More SH exponentiation questions

Has anyone implemented SH exponentiation AND managed to approximate the optimal linear (OL) values for 2 or more sphere occluders? 

The SH paper briefly mentioned/implied that the authors managed to fit the OL approximation to multiple spheres, which still has some artifacts with inaccurate/lighter occlusion, but is still preferable to the single sphere approximation when dealing with multiple sphere occluders, which is common in most "practical" cases.


If anyone has some idea how the fitting to multiple spheres thing is done - that'll be awesome.