VRayMtlID

[^Lele^]

I was unclear in my post, sorry (evening after a long week, i truly didn't see "cryptomattes" in the post i was answering to.).
Not cryptomattes specifically, i was referring generally to non-filtered passes.

For CM, all one needs is a proper reader on the compositing side (i.e. the VFB2, Nuke, Fusion).
Trying to use a cryptomatte as if it was a color mask will very likely fail, or produce wrong/inconsistent results (as CM also stores coverage, which is invisible.).
I should have mentioned trying to pick from inside the VFB2's masking to verify AA quality.

As for "perfect" masks, not quite.
Multimattes have the flexibility to work with the most cases (f.e. mask propagation through refractions), CM doesn't, but it's very good to isolate geo and shaders when directly viewed, also via metadata (i.e. names).
And it's also setup-free, essentially.

[fixeighted]

Hehe ok, I thought that may be the case, then typically (especially early morning) started to doubt my own knowledge

I agree with the other points of course, just personally I'd rather have one CM and then generate specific other matte fixes for e.g. glass.
Options...we love 'em

[^Lele^]

Oh i agree.
In a production with some really clever blokes, a long while ago now, they came up with a prot-version of a masking system, not too dissimilar from CM (for the metadata part. it had no coverage.).
*Plus* the usual metric ton of multimattes.

Options are the salt of life.

[RobH22]

I'm curious Lele - why would you need to render cryptomattes larger in order to antialias them? They are already perfect masks as far as I can see....I thought that was the whole point of using them, because they were mathematically
generated and can see more values and thus create a more faithful mask than rgb can.

I'm by far not very experienced with Cryptomattes at this point but was intrigued by them when I say the latest "What's New" with the update. I started playing with them and found that they are not antialiased at all and even when you enable "Filter" for them, they still have sharply defined pixel edges. Maybe I'm doing something wrong.

But, after following Lele's workflow, they became useful for me. I've always known that reducing an image causes more antialiasing. I just never had the "ah-ha" moment and thought to do a Crypotmatte at 2x or 4x and reducing it to achieve that. It seems like an obvious approach looking backwards but simply evaded me. Anyway, that's my experience. Maybe someone will point out my further lack of experience with Cryptomattes and tell me how to have them antialiased from the start.

Edit: I see my response here is a little out of order as there is more discussion as to how they function. I see now that if you respond to an email that says you were "Quoted" that it takes you to a point that is out of order in the entire thread. I'll watch that in the future.

[fixeighted]

No problem...it's easy to miss things or misunderstand....I do all the time.
Let's blame it on Lele anyway...that's just easier

Anyway, luckily his tip is exact, for that regular matte/zdepth unfiltered workflow, so it is all good information to assimilate

[^Lele^]

Rob, yes, entirely my mistake, i was well past cooked, should have waited for the next fresh moment.
Also, welcome to the vagaries of forum notifications.
They can be useful, and oftentimes irritating.
I feel a kinship. ^^

[fixeighted]

LOL dude...I'm only joking...it's not a blame situation....s'all cool