exclude an object/material from specific light

[rezvan23]

Hi.
Is there a way in V-Ray for Sketchup to exclude an object/material from a specific light?

[Peter.Chaushev]

Hello,

This is not currently achievable.
A user request was logged some time ago, however, this feature has not been planned for V-Ray Next so far. Initially, it was decided against diverting efforts toward its implementation, although final evaluation is still pending.
Our impression so far is that light exclude lists are quite rarely used and therefore not a priority.

Can you describe scenarios in which you find the feature needed and with no alternative workaround?

Kind regards,
Peter

[rezvan23]

I'm trying to set a background plane for my interior scene, but it blocks sun light coming through window. Or there was a scene of a table and a flowerpot which I like to have more light on the flowers, not the table. It is always good to have options which gives you more control. (sorry for my bad English, it's not my native language)

[kenancakir]

For plane use two sided material.. Your picture for front and a transparent material for the back face.. You have to disable cause shadow for each material, from options..

[rezvan23]

For plane use two sided material.. Your picture for front and a transparent material for the back face.. You have to disable cause shadow for each material, from options..

Hi Kenan. thanks for your reply.
I tried this method, I created a 2sided material with my picture (as an emissive material to control the intensity of the background) for front face and a transparent material for the back face. until here it is not satisfying, cause it creates GI which I don't want. So I used a wrapper material to kill the GI, but (I don't know why) it creates a little bit of GI on the surfaces. So here I created a mtlOverride (which for some reason it can't set the 2sided material as the base material) and I set the wrapper material as the base material and a transparent material as the GI override, and it worked perfectly. the background plane object has no shadow, no GI, and light pass through it.
But still it is not a straightforward way which everyone can follow.

The flowerpot and table issue is still unsolved for me...

[kenancakir]

You can use two materials directly inside sketchup.. A transparent material to the back face and your picture to the front face.. You have to uncheck cause shadow from each material inside vray..

[Peter.Chaushev]

For the background plane scene, you can set the image as bitmap texture with Environment/Screen placement (be mindful of the image's aspect ratio) and then override it contribution to the scene.
Regarding the flower pot scene, perhaps best course of action is to set up lighting the same way you would in real life in order to achieve the desired effect, e.g. additional lighting focused solely on the pot and not the table. Alternatively, you can use a couple of Wrapper materials, one with higher Receive GI value, and another with slightly lower Generate GI value for the pot and table materials respectively. An illustration or the scene itself would be needed to provide a more specific advice.

Kind regards,
Peter