Saving the VFB background breaks Cryptomatte

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

In a scene with a Cryptomatte element, add a Background in VFB and save the Background to a multi-channel EXR with “Save in image”.

The output OpenEXR does not work with Cryptomatte Pick on Nuke.
(and EXR-I/O Photoshop Cryptomatte Mask creation does not work properly)

Where is the problem?
Confirmed with 3dsMax 2022 with V-Ray 5, update 2.2

Attach test EXR
https://drive.google.com/file/d/1V8Z…ew?usp=sharing

2

Hi as far as tested on my end everything works. I created a test scene in 3ds max with background layer and saved and it worked. Also tested your EXR and it works in Nuke?

Nuke13.0_2022-03-17_17-53-24.jpg
Nuke13.0_2022-03-17_17-53-24.jpg1919×1160 299 KB

Nuke13.0_2022-03-17_17-59-35.jpg
Nuke13.0_2022-03-17_17-59-35.jpg1624×630 166 KB

3

I’m testing with Nuke 11.3 and ccc.exr doesn’t pick successfully.
The same is Nuke 13.1v3.

Nuke’s problem?

Screen capture
https://drive.google.com/file/d/1r9C\_T9z57GxAe417-BKZmcuY2DbTRCaJ/view?usp=sharing

Note that aaa.exr is an Image that does not include the background. There is no problem here.

aaa.exr and ccc.exr files

4

Hi I did further testing. In my initial test it did work now it does not.
After this confusion I proceeded and was able to confirm that if you load the background image after rendering it does not work but if you load the background image before rendering, render with it and save, criptomatte works.
Let me investigate a bit further and I will get back to you.

5

That’s right. After loading the Background, it will not be rendered again.
It was good to be able to reproduce the problem. Wait for the investigation.

6

Hi I have logged this issue under VMAX-11986 in our system for developer review.

7

Thank you for your investigation.