Gi problem with very basic scene and transparent object

[muoto]

Hello,

i got this very simple scene, a base of a studio set up with a ground+wall and a thin and thick glass object
when i render this, i have this strange ugly GI in the glass...

simple omni, vray dome light, irr map and lightcache

where is the problem ???

Thanks!

ps: attached jpg and max scene

[muoto]

OK, found out that the simple background plane with a simple glossy reflection is messing up the tranparency/gi problem

edit : simple reflection on that plane, even without glossy is messing up the transparency

edit 2 : even without glossy, i have strange GI in the thick glass box...

edit 3 : well... it seems whats messing up, is the vray dome light. When i turn it off, transparency is fine...

is there a fix?

thanks

[peterguthrie]

tick the retrace threshold (and set to 1.0) in the light cache options maybe?

http://www.spot3d.com/vray/help/200R...lightcache.htm

[muoto]

light cache is turned off... just irr map

[peterguthrie]

light cache is turned off... just irr map

so brute force 2nd bounce?

[muoto]

No, nothing as 2nd bounce (just to see where the prob is coming from)

i tried with vraylight planes, even with 256 subdivs, and i also have strange gi effects in the refraction

[muoto]

well...i think it's more irrmap related in a way...
i changed the sample lookup to overlapping, instead of density, and result is much much cleaner !

[peterguthrie]

no idea then i'm afraid, I'm not much of an expert with irradiance maps!

[peterguthrie]

(adding a light cache as 2nd bounce with default settings but telling it to use light cache for glossy rays (not ticking retrace threshold) seems to give a decent result)

[Zdravko]

You would need to enable Affect reflection option of the dome light on order to get a correct result.

[muoto]

hmm..yeah but when doing that, i loose my custom panoramic env map i use for glass materials

[Zdravko]

What exactly are you trying to achieve?
Where do you set the env. map: domelight, environment or environment override slots?

[muoto]

i normaly place a 360° pano in the glass for reflections, and a kind of studio setup for lights and background.

so i just need clean transparency, GI, and light reflection in the glass

[Svetlozar Draganov]

Hello there.

This problem can be fixed if you choose " Treat Glossy Rays as GI = Always" from "Options" rollout of your backplate material.