Light Select Direct Illumination

[kristian_turner]

Hi,

Is there a workaround to get a rectLight reflection contribution to NOT show up in a light select render layer set to direct illumination. This is the way they worked in V-Ray Next. There is a fix to move a domelight's reflection from specular to reflection (adaptive dome and consistent lighting elements), currently in V-Ray 5 light selects aren't really usable for me.

Thanks!

-Kristian

[hermit.crab]

You probably need to switch to the "Direct Diffuse" mode. More information in the docs.

[kristian_turner]

Thanks for the reply!

As I do mostly automotive rendering I need the Diffuse and Specular contributions. Unfortunately a rect light's reflection contribution comes up in the direct specular. I was mistaken above, all the way back in V-Ray 3 this was different, I've asked support for a legacy installer to make sure this wasn't a fever dream.

[hermit.crab]

Unfortunately a rect light's reflection contribution comes up in the direct specular.

Well, yes, that's the Specular (highlights). If you want the Reflections instead, use the Light Path Expression mode and select the Reflections preset. The difference you are noticing is most likely due to the consistent lighting elements (read the yellow paragraph here).

[kristian_turner]

Well, yes, that's the Specular (highlights). If you want the Reflections instead, use the Light Path Expression mode and select the Reflections preset. The difference you are noticing is most likely due to the consistent lighting elements (read the yellow paragraph here).

Thanks for the suggestion, but I can't seem to extract the elements we were able to admittedly a long while back. In the image below you can see the sharp reflection of the light source in the clearcoat of the sphere and the softer spread of the light in the metallic. Is there no longer a way to extract using a light select just the effect of the light on the metallic without the hard square reflection?

I hope this makes sense.

[hermit.crab]

Okay, I saw what you mean. This, indeed, happens because of the Consistent Lighting Elements. You can get the soft highlights separately by:

1. Use VRayLightSelect, with type Light Path Expression. Type the following expression:

C<RG[^'mcoat']>L

This label will yield a specular element without coat highlights. However, it's not light-centric.

2. Extracting the highlight in post. You would need to add a VRayCoatSpecular element for this (which holds only the light's non-glossy reflection). Subtract the VRayCoatLayer from the VRayLightSelect (direct specular mode) and you should get the desired result.

[kristian_turner]

The light path expression works perfectly, even though my car paint material is built manually from a blendMtl and not using a coat in a VRayMtl.

Thanks so much! I'm going to do some testing on a practical file.