Aliased material ID render element - solution ?

V-Ray V-Ray for 3ds Max Issues
1

OK the title sort of expkains it all - I get aliased render elements.

Not sure if this is a problem or just a workflow issue -

Is there a way to get a high quality output ?

NIR

2

MaterialID is an integer Value hence it is expected behaviour.

For masking use MultiMatte Renderelements together with either MatIDs or ObjectIDs.

Regards,
Thorsten

3

How can you do that ?

I use the glass ID for adding reflection in post.

Nir

4

Set the glass mat’s ID or all glass object’s IDs to a any unique value
Add a Multimatte renderelement. Set it to matID or not depending on what way you choose.
Turn on the three channels and set the IDs to the value of the mats/objects.

Regards,
Thorsten

5

Thanks

I will try it.

NIR

6

I tried - no luck.

I did everything you said and got a black image (mutlimatte)

NIR

7

Did you set the Material Effects ID ? Or maybe just the ID on the meshes ?

Regards,
Thorsten

8

Yes I did
I gave the glass material an ID.

9

and you ticked “MatID” in the renderelement and set the right id in the spinner ?

Can you share a stripped down file ?

Regards,
Thorsten

10

OK - the ticking part was the problem - I now get it correctly.

where do I get more info on the multimatte - it is not VRAY specifiec (no mention in the vray docs)

BIG THANKS !

NIR

11

It is vray specific. Probably not in the docs as it was originally developed in-house here and “donated” to Chaos quite a while back.

There isnt much to know tho:

MatID On : Uses MatIDs
MatID Off : Uses ObjectIDs

R/G/B Spinners : Set the desired ID for the respective Channel

You can add as many as needed and hence generate as many masks as needed. Be sure to rename them properly tho.

Regards,
Thorsten

12

THANKS !!

I will save this message for future ref -

BTW you said “HERE” - Where is this HERE ?

NIR

13

Just on multimatte bits thorsten, I’d normally pop one of those out to our flame ops as a grading / separation matte but of course since it’s part of the background it’s like an image premultiplied against a multi colour background rather than being something handy like black - you guys figured out anything smart to pull elements out or would you just go back and render a proper element against black specially?

14

@Nirsul : Mackevision Stuttgart

@jo : Im not sure i understand you correctly there. The element shouldnt have the background. If you mean the elements in front of each other you can simply take the R/G/B channel alone to get a perfect matte in front of black.

Regards,
Thorsten

15

I mean that if you’ve got a render with the frame filled of 3d bits and you want to use the multimatte as a cheap way of pulling out one part only (so you don’t have to go back and render a single object against black) - when you bring that into your compositor you’re going to have a lot of hassle trying to get a clean edge on the object you’ve pulled out of the render due to it’s edges being anti aliased with other colour objects in the scene rather than against black - have you guys done any kind of smart methods of dividing with the full render to get a nice edge?

16

I think that the multimatte will solve this very problem as you can set each additional multimatte to a different ID (be it a material or object) - thus you get a different mask for each - without the blended (AA) area -

Did I get you right ?

NIR

17

You are indeed right - the matte itself is totally clean but since the rendered object might be against other objects in the scene in the main render it’s going to be much harder to separate than an object that was rendered against a pure colour like black or white. When your compositing app gets to the anti aliased edges it has a harder time trying to unpremultiply them.