Problems separating self illumination light contribution to Render Element

[danielmeitin]

Hi there,

 

I'm new to the forums and haven't been working with Vray for long, so excuse me if I am not so knowledgeable. I am trying to set up my scene for rendering with a few Render Elements, nothing too complicated. The scene is an interior illuminated with a Dome light, a VRay rectangle light and two stained glass windows that have a VRay Light Material applied to them. So, the elements that I am using (well, the ones relevant to the lighting of the scene) are GI, a Light Select for the dome light, another Light Select for the Rectangle Light, and Self Illumination for the stained glass windows. Everything seems correct to this point. The thing is, both stained glass windows have the Direct Illumination checker (under the Direct Illumination tab on the attributes of the Light Material) set as active, so the material emits light. And I don't know how to extract that light contribution to a separate render pass... The composite of my render passes doesn't look like the RGB pass, it's missing just that bit. Could anyone give me some hints on how to do it or point me to any tutorial? I have been looking for a while with no luck. Any help would be greatly appreciated

 

Cheers!

[Corey Beaulieu]

If you save out a Lighting Element and then an Element for each of the lights in your scene...... Save your files to an EXR and in PS, 32-bit mode, set your Lighting Pass to Normal and the Light Selects to Subtract on top of it. This should leave you with any direct light contribution from your glass.

[danielmeitin]

Awesome, you're a star!! At first I wasn't getting it, because I was setting the layers as you described, on my normal composition.... but what you meant was creating that render element by myself by subtracting the lights from the lighting pass, and the using the result of that on top of my old composition, right? That's clever! I can see a slight difference when comparing to my RGB pass, but nothing dramatic.

 

Thank you so much!!

[Corey Beaulieu]

Yes that is what I meant.

 

Usually the difference between the RGB and the re-comp of the RGB through Elements in 32-bit is the Color Mapping. If you use any Burn value other than 1.0, that will only be stored in the RGB pass, not the elements.

 

All the same, glad it worked out for you.

[danielmeitin]

Thanks again Corey! Sorry to bother again, but I was wondering if you would know about another issue I'm having with this render. There's an object with a Vray Material applied to it, with just a map plugged into the diffuse colour slot, and an opacity map into the opacity slot. The thing is, the object looks okay in the RGB layer, but it looks faded and dull in the composite (while the rest of the scene looks okay). I am guessing it's also a Render Elements issue. If I can't find any way around this, I might extract the object from the RGB layer using Material ID as a mask, but I'm afraid it won't look as it should and it may require more work to make it match with the rest of the scene. Do you have any idea why this could be happening?

 

thank you!