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Viewport render better than final render
Confirmed, NormalPublicBUG


System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: Radeon (TM) RX 480 Graphics ATI Technologies Inc. 4.5.13587 Core Profile Context 20.2.2 26.20.15019.19000

Blender Version
Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: rB0330d1af29c0
Worked: (newest version of Blender that worked as expected)
tested in 2.90 and 2.91 Alpha

Short description of error
The viewport render handles shadows much better than the final render.

viewport, no denoise:

Render, no denoise (there are quite big black spots in shadows):

Exact steps for others to reproduce the error

  1. Open file
  2. Go to rendered view
  3. Render an image ( F12 )
  4. Compare the results

Triaging notes:
This issue exists only when Adaptive sampling is enabled and Min Light Bounces is 0

Event Timeline

Julian (Dukes) updated the task description. (Show Details)

at first I thought this would be caused by the resolution that you where using in render but even after increasing the resolution it still gets a really bad denoising.

the next renders were made with the same sample count and close enough resolutions, the floor had a solidify modifier that is only activated on render, so I deactivated totally it to have the exact same situation for both(If I did not miss anything else)

viewport, denoise

Render. denoise

So I decided to render them without the denoiser, and to my surprise the render one is not only different, its worse, notice how it has some Big black spots intead of a more even noise.

viewport, no denoise:

Render, no denoise:

So the problem is not the denoiser, its something else, so I tried to deactivate adaptative sampling and here is the render result with denoising

If the documentation is right this was not supposed to have such noticeable difference with denoising

and particularly after denoising the result will be almost indistinguishable.

it looks like it just glitched in that specific area.

by the way, may be related to the bug, your portal light is pointing to the outside, I guess it should point inside the room, even with adaptative sampling ON the bug does not happen when its turned to the right side

Oh yes I forgot the solidify modifier in this file but I tried it without and it didnt change anything.

I tested with and without portal and I had no difference. So should it always point inside the room? I saw tutorials where the portal points inside and sometimes outside so I thought it doesnt matter.

So adaptive sampling fixed it?

I had a computer monitor in this scene too and the reflection on the screen were also a bit glitchy. I could show you later if it helps.

I think what caused it was probably the adaptative sampling only, and since that looks like an area where it should be using more samples and not the other way around, it may be an actual bug, tho I can't confirm it.

Even with 20000 Samples I have these black spots. What worked for me was to delete the window. But I will test it with this portal thing and adaptive sampling.

I can confirm this, To me this doesn't look like T75618, because those were spots where no rays were cast to. Here I can see suspiciously black spots, but only in diffuse indirect pass so it may have common cause perhaps.

Clearing render region did not help in my case.

What did help was to increase Min Light Bounces to 2. Perhaps this is somehow different in viewport render?

Richard Antalik (ISS) renamed this task from Viewport denoise better than final denoise to Viewport render better than final render.Oct 6 2020, 6:20 PM
Richard Antalik (ISS) changed the task status from Needs Triage to Confirmed.
Richard Antalik (ISS) updated the task description. (Show Details)
Richard Antalik (ISS) updated the task description. (Show Details)
Brecht Van Lommel (brecht) changed the subtype of this task from "Report" to "Bug".Jan 18 2021, 12:36 PM