from time to time i am facing the same problem with architectural vizualisations: buildings with grass in front of it get a terribly green
touch because of the secondary light bouncing off the ground.
in fR and the max “override advanced lighting”- material there is a
setting for the intensity of color bleeding. is there something like that in vray or does anyone know a workaround?
thanks s.
good question - I have the same problem…
anyone?
unfortunately the work around is basically having to use a less saturated ground when calculating irradiance maps. then replacing it at render time. however there is a huge bug with this. if you use interpolated glossys it will need to render the passes for that. and those passes will render the reflections with the current saturated green. so even though a wall would look better with this method, it would look green in the glossy reflection cuz the glossy is calculating it with the current green
What about diminishing the generate GI coefficient in the Object Settings area?
that could work as well. however. it means the light bounced back up is not that strong anymore.
the ground should - of course - bounce light but not so saturated!
the workaround, da_elf is talking about, sounds good…
there is a program called dsatvraymap around here.
never tried, but should work..
regards
s.wolf
Bingo!! you ask why the box doesnt have a green tint to it even though its sitting on a green grass. well. simple. a: do all your modeling and texturing and when your ready to render. hide everything except your ground. render that out and save it. then i load that same image into my environment background slot. The ground now i change to matte shadow material that accepts shadows etc. in the material slot ive got a vray material which the diffuse of it controls the color of the GI light comming off the matte shadow. if i had a red diffuse then the box would be red even though it sits on green grass. see!!!
For your enjoyment. have a happy vray holiday 
hehehe
I did this with the same technique.
i remember having a lot of problems with color bleeding, especially since im a ligthscape user and i’m used to having a color bleeding override…
Anyway, i did an animation by rendering the backround first and then applying a matte to the grass object.
where can i find this dsatvraymap ?
which version dusan
hi dusan
i have recently joined this forum
saw ur render here
curious about which version of vray u use.
thx
where can i find this dsatvraymap ?
here:
ftp://ftp.hdrinc.com/4OMA/4cocolas/vrmapDesat.exe
hope it helps!
paul
here:
ftp://ftp.hdrinc.com/4OMA/4cocolas/vrmapDesat.exe
hope it helps!
this is a joke or WHAT ?
a program to desaturate maps??? very funny[/quote]
Colour bleed solution
I’ve had the same problem as you mentioned as well and I overcame it by doing one render pass and saving the irradiance map out. In this pass you desaturate that material to basically bleed no colour off it. Then for your second pass use the irradiance map you saved and render the image with the amount of saturation that you want producing a rich coloured grass and not to much bleed.