Why are my VRayMtlWrappers not working (as I expect them to !)

[JezUK]

Using VRay ADV.

I want to render a room and matte out everything so just the skirting and door framework remain but when I make all the other materials in the scene have a VRayMtlWrapper (and set the all the Wrappers have all the same settings as below) - the frame and skirting are indeed the only objects visible in the scene (which is what I want) but very overlit as though those wrapped materials are not generating GI etc (as you can see on the left 1/2 of the image how much brighter the woodwork is to that on the right).

Can someone please enlighten me as to what I'm not doing or setting correctly please ?

Any ideas ?

Thanks

[Morbid Angel]

you need to set reflection amount to 0 if I understood correctly.

[JezUK]

you need to set reflection amount to 0 if I understood correctly.

Unfortunately that's not it.

I want to have the Frame and Skirting *visible* and everything else INvisible, but of course I want the Frame and Skirting to be illuminated with shadows and reflections on it as though everything around it is still 'present'.

Does that make sense ?

(as you can see from my attachment, when I try using MaterialWrappers, yes, they are all invisible, but then the Frame and Skirting is very over exposed (almost as though it is outside and therefore overexposed to the VRay Sun).

[kosso_olli]

Well, for some reason I don't like the material wrapper. I always use the V-Ray properties, which give you the same settings.
So, select the objects you don't want to see and open the V-Ray properties. There, only tick the matte surface checkbox, nothing else. Alpha contribution -1.0
Set reflection, refraction and GI amount to 0.

[JezUK]

Thanks Kosso_Olli,

I really appreciate it

But when I do that to the ceiling - the place is flooded with light - I've got a VRay-Sun in there, as well as a HDR Environment on a V-Ray Dome, if that might throw some light on things..... (no pun intended)

[kosso_olli]

You don't set the objects to "Visible to Camera" off by accident, do you?
It might as well be a bug then, although I never encountered any problems with that setup. Can you share a part of the scene? Just the doorframe with the wall next to it, perhaps?

[Morbid Angel]

I never use mtl wrapper. The same can be done through vray object properties. They have to be visible to camera, the rest should be exactly like you have it in vray mtl wrapper, but I suppose there might be something else going on - care to share part of this scene?

[JezUK]

Thanks guys,

Dmitry, I don't have a problem with sharing part of the scene, but it really is a bog standard room that's easy to set up - 4 walls, floor, ceiling all separate objects, two window openings (skylight portals for both), a dome light with a hdri in the texture slot and a VRay Sun.

When I have tried both wrapper and VRay Object Properties, it's the same issue, as soon as you take the ceiling away, then it's the Sun which is blasting the light onto that door frame and skirting, so to me that is maybe a limitation / bug / needs refining ?

All the examples I've seen where others have used wrappers etc, there is no sun in the scene, it's a simple scene with a ground plane, nothing in the Environment slot (so the surroundings are black) and so in those examples, Wrappers seem to have no issue.

That's my (limited) experience.

Thanks two you both for trying to help.

Maybe someone from Chaosgroup can chime in ?

[kosso_olli]

I just tested this, and I got the same result as Jez. The whole interior basically becomes super bright when set to matte. Super weird bug!

[JezUK]

Chaos said to disable "No GI to other mattes" but I tried this and it still didn't work for me - so I have sent them the file and I will share the solution once I have it.

Thanks guys for trying to help - I appreciate it.

[kosso_olli]

Chaos said to disable "No GI to other mattes" but I tried this and it still didn't work for me

Doesn't work here either. Anyway, I am curious what the solution is.

[Morne]

Tested with Beta2 and I get same "broken" results as Jez

[Zdravko.Keremidchiev]

The wall (and some other geometry) had VRayProperties set to Matte with "No GI to other mattes" enabled which overrides the wrapper Mtl assigned to them.

[JezUK]

Thanks for your help Zdravko,

Here are the settings that were recommended by Chaos;