Render layer masks bad w/ DOF when Alpha enabled in kernel

[bartolos]

Hi,

There is a problem with render layer masks when there is DOF in camera *AND* there is Alpha Channel enabled in Kernel settings. It makes layer masks render like if there was Distributed Rendering turned off, while it actually is on.

As soon as I uncheck Alpha channel in Kernel settings the problem goes away, and the masks are perfectly matching DOF blurs.

I am not using any other render layer features or passes. Just main beauty + ID masks for 3 object groups.

Quite a bad surprise for me, getting humiliated in front of a client as I sent them botched masks without even realising something's wrong... I didn't know the kernel alpha setting could have such consequences...

Interestingly after the fact I did some tests and it seems an Object Layer Color buffer seems to be properly blurred (while layer ID masks are still "hard").

See attached what I mean...

The picture on the top shows properly blurred layer id masks when Alpha is disabled in Kernel options - and that was the only thing I changed and re-rendered.

Cheers,
B

[aoktar]

Check these in a external compositing program not in picture viewer.

[bartolos]

Please read more carefully. The files were sent by me to a client, and that's where I found out about the problem.
Do you think I would bother spending time writing here just to complain about PV display errors?

Wow... I'm flattered.

[aoktar]

I don't think anythings like that but this has been asked many times if i got it correct. And answered as much as. See my picture.

[bartolos]

Can you please explain this?
The only difference in settings between those 2 pictures is disable/enable alpha in kernel render settings.

[aoktar]

I can't see any difference in After Effects for saved images. This mask think is a extraction from render_layer feature of Octane. It extracts the alpha in extra render sessions. Note that i'm using png format.

[bartolos]

I was using multi-channel EXR file.

I think there is some logic there which makes those ID masks "straight matte" when there is Alpha in kernel enabled. That way post-multiplying them by alpha smooths them out.
But this is confusing, and does not work when there are more render layer IDs mixed together like in my case above.

I mean - the render layer ID masks seem NOT to be usable like C4D-style Object Buffers.

But now I will happily use the object color masks...

[aoktar]

I mean - the render layer ID masks seem NOT to be usable like C4D-style Object Buffers.
.

It's usable for me with proper format. It's your decision to use or not.