VRay 5 VFB Cryptomatte masks no longer available after update to previous rendering

[anthony_billet]

Hello, in an attempt to utilize compositing in the new VRay 5 VFB, we have been attempting to use the Cryptomatte masking techniques. We created an image for a client and did some basic Light Mix adjustment and proceeded To Composite. After adding a few adjustment layers we saved out the VFB layer settings which we considered the Final settings should we need to go back adjust the model for the client and update with anything.

After the client had come back with some updates, upon re-rendering the image and loading the VFB layer settings, Cryptomatte masking we had done is no longer functioning and returning the message of Missing Element. The new rendering has the same render elements as the previous rendering. We can flip through them from the drop down menu but are unable to add Cryptomatte masks in the layer panel after loading the Final settings file we created.

Our current course of action is just to redo the compositing layers based off the old render by hand and matching the old layer settings.

Is this a known issue? An issue created upon re-rendering the image? An issue with loading settings? Is there a best practice here to resolve our issue going further?

Thanks!

[hermit.crab]

Odd, seems to work fine on a simple scene. Could you attach the stripped scene here or send it via the contact form so we can take a look? Mention me and include a link to this thread.

[anthony_billet]

Aleksandar,

After some testing and re-rendering we think the issue came down to the method of saving the .vrimg file. We could get the VFB layer settings to work correctly when we specified to save a .vrimg file from the Render Settings panel in 3ds max. Previously, the render was saved after the render was complete from the VFB by choosing Save All Channels to a single file and specified .vrimg. Is there a sort of "collapsing" of Cryptomatte data when saving out from the VFB with Save All Channels?

[hermit.crab]

Do you have a background layer? There is a known issue where Cryptomattes get broken when saving Background layers (check this thread).

[anthony_billet]

Aleksander, we are utilizing the VRayBackToBeauty which looks like it has VRayBackground in it. So if we are opening up the VFB from a brand new scene/file, and load the .vrimg file into the VFB, Cryptomattes will break at this point? The above thread does appear to be the same issue.

[hermit.crab]

The issue occurs when adding a standard Background layer (not VRayBackground) after rendering. Maybe it's something else. Best you send the scene as instructed above.