Cryptomatte and Z depth doesnt work

[AdrianDudak]

Hi all,

so I am experiencing issues with my Maya scene when my rendered multi-layer EXR sequence has incorrect/ broken Cryptomatte and Z depth passes.

CRYPTOMATTE  issue:

- they are set up from AOVs, nothing changed to its default settings (like this in the past it worked without issues)

- rendered with Render Sequence, its multiLayer EXR with Merge AOVs checked

- in Nuke when I try to use Cryptomatte to select either by object or by material, I see this: 

You can tell just by looking at it something's wrong. Selecting the car body selects also tyres, spoiler and background (while there is no background to start with, its a render layer of a car only). it happens with all render layers in the scene (car/env/etc...)... not to mention they are NOT the same material...

Z DEPTH issue:

- my Z depth comes out as solid flat color without any actual Z depth to it.. when I contrast/under expose my Z depth AOV to see the depth, its either flat or has only some weirds scanlines instead of actual Z depth...

- again, all settings are default I didnt change anything to it (as far as I am aware)

In previous scenes I used exactly same settings (as far as I am concerned) and I didnt have any of these issues so Im not sure what Im missing here. Im rendering on CPU

Specs: Maya 2023, Windows 10 64 bit, 64GB ram, RTX2080 8GB, rendered in ACES (as set by default)

Any suggestions as to what might be causing this ? Is it some bug or did I just screwed something in settings?

Thanks in advance

[Stephen.Blair]

I don't remember seeing any issues like that. Do you have repro scene you can share?

Is there anything in the log? What else is in the scene (imagers, operators, ...) ?

If you render just Z, or just cryptomatte, are the both still broken?

[AdrianDudak]

thanks for the reply. The scene is actually quite heavy to share, but perhaps I can try to reduce it to a minimal area. No it doesnt contains any imagers or anything like that

EDIT: but what I do have in the scene is quite a few alembic caches of animated characters

EDIT 2: I solved the Zdepth issue - it was read node's color space that caused the Z pass to go flat. Due to ACES workflow I was swtiching read nodes from Scene Linear to Output sRGB to match the look of my Arnold Render's view, but it doesnt solve the cryptomatte issue

EDIT3: removing Z and N AOVs to keep just cryptomattes as you suggested ddint help either

[AdrianDudak]

Here is the archived reduced scene https://mab.to/YEjoYEB7T, hopefully it will work on your end.

Apart from that I noticed another issue I forgot to mention (I dont want to start a new thread because something tells me this all has a common root) is that when I break my beauty pass in Nuke to diffuse/specular/coat/transmission and plus them all together, they dont match the beauty, there is a slight difference:

this is the actual difference: 

I checked my scene and I dont miss any other AOV such as sheen etc as I dont use those in my shaders... Any idea what might be causing this?

Thanks

[Stephen.Blair]

Just to be sure you get everything, can you try with
diffuse, specular, coat, transmission, sss, volume, emission, background

[AdrianDudak]

Hye, so after investigating further it seems like both issues were caused by color spaces, more precisely wrong output transform that was impacting Z and Cryptomatte passes. It all seems to work now

[osukas]

just adding because this problem happens to my coworkers

when they use the node REFORMAT in Nuke, the cryptomatte gets detroyed. You need to create your mask first with crypto, and then use reformat. We do this way because of time constraint we rendered in 3k and reformated the render to 4k