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Compositor/Stereoscopy with view switch and file output generate extra files
Confirmed, NormalPublicKNOWN ISSUE

Description

Blender Version
Broken: 2.79, 2.81, ...
Worked: ?

Short description of error
when using Stereoscopy to render a scene from multiple cameras simultaneously, and using the compositor 'Switch View' node to save each camera output separately - unwanted files are saved with each output file.

Simpler version of the report

The combination of the switch view node, mix RGB node and rgb node is creating the problem, disabling even just one of those three nodes produces normal results.
The bug is reproduced only when all mix nodes are connected to the same RGB node, but connecting each node the a duplicate of the same rgb node seems to resolve the problem (see screenshots attached)

Sample file:


For the records the issue also happens in 2.79.

Original description of error

In the attached .blend are 9 cameras set up with sterescopy. The compositor separates and saves each camera output to a different directory.
For some reason, with every file output from a certain camera there's another file output from a different camera (lets call it parasite camera) , only this one is black with no data (see attached screenshot).
a few charasteristics:

  • The parasite camera output is added to every output of the other cameras, but not to its own
  • Rendering again changes the parasite camera to a different one (in the screenshot it was 'Cam006', in other renders it was a different one)
  • It's not clear how the parasite camera is "chosen", it isn't selected or active, and it's not the scene's camera
  • There's no file output in the compositor that suggests this output


Event Timeline

Jacques Lucke (JacquesLucke) changed the task status from Needs Triage to Confirmed.Jan 8 2020, 11:57 AM

I can reproduce this issue. However, could you please provide a simpler file that has the same issue? Just two output nodes should be enough, right?

Dalai Felinto (dfelinto) changed the task status from Confirmed to Needs Information from User.Jan 10 2020, 3:29 PM

Not confirmed if we still don't have all the information to fix the issue (in this case we do need a simpler file).
Also, is this happening in 2.79 or not? The sample file can be made in 2.79 even.

alright, so I've been trying to reproduce the bug in a simpler file and may have discovered exactly what causes it and how to avoid it!
It seems like It's the combination of the switch view node, mix RGB node and rgb node is creating the problem, disabling even just one of those three nodes produces normal results.
The surprising fact is the bug is reproduced only when all mix nodes are connected to the same RGB node, but connecting each node the a duplicate of the same rgb node seems to resolve the problem (see screenshots attached)

(attached is a simpler file that reproduces the bug)

Philipp Oeser (lichtwerk) changed the task status from Needs Information from User to Confirmed.Jan 16 2020, 12:07 PM
Philipp Oeser (lichtwerk) changed the subtype of this task from "Report" to "Bug".

Thx for digging deeper @ADI SAMSONOFF (adi.samsonoff) , can confirm.

Dalai Felinto (dfelinto) renamed this task from Compositor/Stereoscopy bug to Compositor/Stereoscopy with view switch and file output generate extra files.Jan 16 2020, 12:22 PM
Dalai Felinto (dfelinto) updated the task description. (Show Details)

Thanks indeed, it helps a lot this sort of simplification. I updated the report to contain all the updated information. Also making sure the proper module (VFX & Video in this case) is tagged.

Jeroen Bakker (jbakker) changed the subtype of this task from "Bug" to "Known Issue".May 26 2020, 11:40 AM

when using the file I see it creates the next files

Saved: Output/Cam1/Image0001_Cam01.png
Saved: Output/Cam2/Image0001_Cam01.png
Saved: Output/Cam3/Image0001_Cam01.png
Saved: Output/Cam2/Image0001_Cam02.png
Saved: Output/Cam3/Image0001_Cam03.png

So it seems to be faulty when rendering the first view.
The file output node saves an image when its resolution is set to something else than [0,0]. In these cases it gets the resolution of the MixRGB -> RGB node.

Issue is also that the Switch View node isn't designed to split the graph, but for joining the graph. I will set this to known issue I don't see any solutions without breaking other setups.

A solution could be to have a view-filter in the file output node and not based on the dimension. but that is a workaround.