Cycles Depth and Mist passes for a transparent material give a lot of noise

I was trying to answer to the question on Blender Stack Exchange.

depth_test.blend (213.9 KB)

Here is a way to bypass the noise. I think it is a bug, but I am not sure because I tried to recreate it in 2.79, and It did not work. It seems the noise was always present, and a high sample level does not help.

If it never worked but had this buggy nature, should it be reported as a bug or a feature request? Anyway, as presented, Blender can do it.

It has something to do with the object data of Plane.000. If you copy the object data from Plane.005 to Plane.000, the noise goes away.

No, you just copped the weirdly fixed material with that data. I tried it on many things. The noise won’t go away without the trick.

I updated the .blend because using Holdout wasn’t great. It also works with any non surface shader output, including Emission.

Switch to branched path tracing.

Thanks, It seems that Path Tracing ignores min_transparent_bounces which were added back. Or should it? If so, It is not obvious.

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