VrayAmbientLight making white objects VERY white

[tricky]

I'm pretty new to using the VrayAmbientLight + VRayDirt to simulate GI, but we are working on an animation where it may be necessary.

What I like about it is the apparent simplicity. I am using a VrayCamera and VraySun/VraySky. I have created a VRayAmbientL:ight and dropped a VRayDirt material in the slot with a falloff radius of 500mm. It gives pretty good results, but what I find is that the white objects (that looked fine when rendering with normal GI) are very blown out. What is the reason for this? Do I need to essentially darken all my white materials?

[tricky]

If I reduce the light map value from 100 (default) down to 4 (!) its looking about right. I'm pretty sure this isn't the way to do it though - I thought you had to leave the value at 100???

[Laserschwert]

Instead of reducing the light map value, you might use "exponential" exposure in the color mapping settings... or use "Reinhard" and play with the "burn" setting (somewhere between 0.5 and 1.0)

[tricky]

Instead of reducing the light map value, you might use "exponential" exposure in the color mapping settings... or use "Reinhard" and play with the "burn" setting (somewhere between 0.5 and 1.0)

Thanks for suggestion, however, my color mapping settings work fine with GI enabled (and the vrayambientlight switched off) in the same scene, so I'm not sure that colour mapping would be the thing to change to solve this. I could (and probably am) be talking rubish though!

[flino2004]

double check if the default lights are always OFF under Global settings, by default they are "OFF with GI"

Fernando

[tricky]

double check if the default lights are always OFF under Global settings, by default they are "OFF with GI"

Fernando

Sounds prom,ising - will check.

[tricky]

Nope - tried forcing them off but no change.

Maybe it is a colour mapping issue afterall. Any other ideas?

[flino2004]

I have to do some test about it ,but I'm assuming if you use vraysky even if GI is off still you have ambiental like from it so if you add vrayambientlight you have 2 ambient lightand white surfaces will capture more light.... I'll test it.

[flino2004]

It didn't work...I did another test using vraydome light with vraysky in there("Use texture" ) and an ambientlight(very low) with vraydirt and vraysun as direct light. It seems to work well

Fernando

[tricky]

I'd hoped that there were one or two more pointers as to why white objects are blown out when using vrayambientlight + vraydirt to fake GI, but from what I can see, there is very little info on this.

Any more ideas?

[Svetlozar Draganov]

Is it possible to attach a sample scene?

GI is different than Ambient Light with VrayDirt - and the result won't be the same by default - but a little tweaking you can achieve similar results.

Turn off all the lights in the scene - including background and any kind of overrides - leave only the Ambient Light with VrayDirt on it.
Now play with the Vray Dirt Parameters - occluded / unoccluded color and radius - until you get close result to what you have with GI.
If both occluded and unoccluded colors are white - the color of the materials in the renderer should be the same as they are in the material editor - i.e. - if you have a diffuse with 235,235,235 color - the color in the renderer should match it.

Please post a scene if it is possible.