refraction related

[shaggray]

i got a few questions about refraction:

1. what are "refractive GI caustics"?
2. does glossy refraction affect irradiance map calculation?
3. does this have to do with "refractive GI caustics"?

[flipside]

GI caustics are caustics created by GI light. GI light is all bounced light in the scene ("secondary light"). Skylight is also considered GI light. In fact in real life all caustics are the same, from whatever kind of light, but in CG these are usually seperated. Normal caustics in vray only come from the first ray of the lightsources in your scene.

GI caustics are usefull if you want more GI light to pass through glass.

reafractive GI caustics are the refractive part and reflective caustics are the caustics from reflections of course. It's a pity vray only makes this distinction for it's GI caustics and not also for the direct caustics btw.

Usually if you hide your glass windows, compute irradiance map and then set vray to reuse it (not add to current map or incremental!!!), this should work perfectly because no additional samples are calculated (or GI caustics or whatever). Regarding your previous post, I don't know what causes the blotches.

If you would calculate IR with windows on and GI refractions on, the IR map would surely be different with or without glossy refractions, because these affect the refractive GI caustics.