www.kraytracing.com

After seeing the HUGE quality difference between irradiance caching in modo 201 and modo 202, it seems that irradiance gradients is something you REALLY need to add to Kray, Grzegorz!

One of the cool things about it is that it also enhances the quality of bump mapping in conjuction with irradiance caching, since it keeps data about the direction of the light. With irradiance gradients, Kray wouldn't need to take extra FG samples on bumps. Awesome!

Here's a PDF:
http://radsite.lbl.gov/radiance/papers/erw92/paper.pdf

Qouting what G. has said about this very question:
"I can't add such improvments becouse they are already here. Irradiance gradients are in Kray from 1.2 i guess, but a big bug was fixed there in 1.6.
Secondary irradiance cache is good for path tracing. Photon map/Light map is in fact secondary irradiance aproximtion that works like cache.
I'm sure if you set lower fg rays in modo 202 you can still see splotches and there also should be no problem to make Kray look like modo 202 render. What it more I can bet new multithreaded Kray can render it faster with the same quality then modo 202 did. "

Also FG is not calculated on bump surfaces since 1.6 I belive...

Ahh, okay then! Nevermind!