VFB Render Elements

[DCHA34]

Hi,
Would it be possible to add in VRay for Sketchup the "VRayMtlSelect" render element that we find in VRay for 3DS MAX.
Very efficient for a complete compositing in VFB.

[konstantin_chaos]

Hi DCHA34,

The element can be added for sure.
However, I don't think that many people will be able to utilize it when compositing.
Can you give me an example of how you use it?

Regards,
Konstantin

[DCHA34]

Hi Konstantin,
when doing architectural renderings, I am very often forced to retouch the colors of my materials according to the "real" colors of the manufacturer's materials.
I was thinking while watching this tuto
https://www.youtube.com/watch?v=JKlf_BChX50
that it would be more "visual" and easier to have this rendering element to make color corrections on my materials (whether they are made in VFB or in Photoshop) than to manipulate masks.

But, maybe there is an equivalent process in Sketchup?

[konstantin_chaos]

Hi DCHA34 ,

Thanks for sharing the video.
The closest thing you can currently do in SketchUp is to add a material mask and then change the color of a material using it.
There is one specific thing in the workflow from the video though - a material which is a base in a blend is manipulated separately, leaving the coating unchanged.
This is not something you can easily do without the material select and I guess this is where its main strength is.

If you do not use a lot of blend materials (in which the base layer is metallic and colorful / carpaints) and just want to change the diffuse color of an object you can still do it without the material select.
Here's how you can do it:

1. Add the Back To Beauty element in your project. This element will automatically rebuild your beauty image from it's base elements
2. Add the Diffuse and Raw Total Light elements yourself. The idea of this step is we will replace the Lighting and GI elements that the Back to Beauty creates with these two. This will allow for Diffuse color manipulation without affecting the lighting of the object (not accounted for in the video you showed me...)
3. Add a Material ID attribute to the material you'd like to manipulate.
4. Set the Material ID to 1
5. Add one last element - MultiMatte Materials
6. Render - the Back to Beauty comp will automatically appear in the VFB
7. Disable the Lighting and GI elements
8. Create a Folder(mode: Add) containing 2 new elements - Diffuse(mode: Override) and on top Raw Total Light(mode: Multiply)
9. Now add a Hue/Saturation correction above the Diffuse and under the Raw Light.
10. Mask the Hue/Saturation layer with a MultiMatte mask

Here's an example project in which I've done the setup - Comp_001.zip


The suggested setup looks complicated but is the correct thing to do and can be saved as a VFB layers preset.

Konstantin

[konstantin_chaos]

And by the way - the 'Lighting comp folder' can be Subtracted from the Beauty and then added (similar to what's shown in the video).
In this case you will not need the full Back to Beauty layers stack...

[DCHA34]

Thank you Konstantin.

I just tried it out, it does work, but it's still quite a heavy workflow.
It's not very intuitive to have to select materials by red, green, ... masks of the MultiMatte element. It would be easier to select materials by their name.

It seems to me that adding the "VRayMtlSelect" render element in Sketchup would be a good thing.

What do you think about it ?

[konstantin_chaos]

Well, the R, G, B workflow is the standard in the film industry because it gives you perfectly anti-aliased masks (compared to the random color mask elements).
I'd recommend you look into the Cryptomatte as an alternative - it doesn't not require any material specific setup.

As for the Material Select:
I'll consider adding this element - we already have a bunch of elements and one more will not make a big difference...
Keep in mind that the Material Select workflow from the video will lead to the diffuse and specular/reflection layers of the material to be corrected together which is not ideal.