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Compositor - ID Mask Anti Aliasing not working
Closed, ResolvedPublicKNOWN ISSUE


iMac Retina Late 2015
OS X El Capitan

Blender 2.78a
Worked: 2.76

Anti Aliasing in the ID Mask Node doesn't work anymore.

Left side: Blender 2.78a Right side: Blender 2.76

Event Timeline

Sergey Sharybin (sergey) lowered the priority of this task from 90 to 30.Nov 8 2016, 10:17 AM

This was an intentional change in rBfeb574f. The issue was that adding two masks did not give proper full coverage of the image causing compositing artifacts.

However, here it seems there is no AA at all (hard to tell from just seeing the image). It might or might not be a real issue here.

This is why it is always important to attach .blend file which demonstrates the issue.

Here's the blend file

Sergey Sharybin (sergey) raised the priority of this task from 30 to Normal.

Ok, there is AA in the mask, but it seems to be not enough to give smooth edges. Will try to tweak some parameters to solve both of this problems..

Any news here?
I can confirm that although anti aliasing works, it was much better before.

Dalai Felinto (dfelinto) triaged this task as Low priority.Jan 21 2020, 4:47 PM
Dalai Felinto (dfelinto) changed the subtype of this task from "Report" to "Known Issue".
Dalai Felinto (dfelinto) edited projects, added VFX & Video; removed Render & Cycles.

This is a know issue, a limitation of the current alias algorithm/implementation.

We currently have the AA node. From workflow point of view masks can be added and AA afterwards.
For more complex setups use Cryptomatte.

My proposal would be to use the SMAA operators for AA in ID Mask with the default settings. How to use these operators can be found in AntiAliasingNode::convertToOperations.

Hey, I'm a new contributor, and I'd like to pick up this task.

I just submitted a possible patch for this at