Maniphest T101693

Principled Volume Not Rendering With Film> Transparency Checked
Needs Information from User, Normal
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Assigned To
None
Authored By
Ben Mckinny (ben.mckinny)
Oct 8 2022, 9:30 AM
Tags
  • BF Blender
Subscribers
Andrew (cs32)
Ben Mckinny (ben.mckinny)
M (NeoTrantor)
Omar Emara (OmarSquircleArt)

Description

System Information
Operating system: Windows 10
Graphics card: NVIDIA GTX 1070

Blender Version
Broken: 3.4.0 Alpha (prior to this 3.2.0)
Worked:

Short description of error
With transparency checked in Film dropdown, volumetric Sim. can be seen while rendered image is in progress, but upon saving the final frame, there's nothing. (No emission or density in principled volume node, all temperature and blackbody)

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Import VDB
added principled volume shader to VDB
only add temperature and black body adjustments
Check Transparent in Film column in render settings
Render image
Save as

Hand Rigged.blend8 MBDownload

Hand Rigged.blend18 MBDownload

VDB 8.zip138 MBDownload

Related Objects

Event Timeline

Ben Mckinny (ben.mckinny) created this task.Oct 8 2022, 9:30 AM
Omar Emara (OmarSquircleArt) changed the task status from Needs Triage to Needs Information from User.Oct 10 2022, 2:06 PM
Omar Emara (OmarSquircleArt) added a subscriber: Omar Emara (OmarSquircleArt).

You didn't attach the VDB file, can you do that? Does this happen when saving PNG images only or also OpenEXR images?

Ben Mckinny (ben.mckinny) updated the task description.Oct 12 2022, 8:42 AM
Ben Mckinny (ben.mckinny) added a comment.Oct 12 2022, 8:45 AM
In T101693#1430143, @Omar Emara (OmarSquircleArt) wrote:

You didn't attach the VDB file, can you do that? Does this happen when saving PNG images only or also OpenEXR images?

Try downloading the file now. I repacked all of the resources.
Also yes, I've tried both PNG and OpenEXR formats (with alpha background of course) still the same problem.

Omar Emara (OmarSquircleArt) added a comment.Oct 12 2022, 9:26 AM

I don't think VDB files gets packed correctly. Can you just attach the standalone Fist Flame VDB 8_0000.vdb file?

Ben Mckinny (ben.mckinny) updated the task description.Oct 12 2022, 9:31 AM
In T101693#1431113, @Omar Emara (OmarSquircleArt) wrote:

I don't think VDB files gets packed correctly. Can you just attach the standalone Fist Flame VDB 8_0000.vdb file?

Sorry about that, I added the VDB to the question^.
Thanks for your help!

Omar Emara (OmarSquircleArt) added a comment.Oct 12 2022, 10:30 AM

This seems to the same issue in T81199. But that only applies to PNG images and you say this also affects EXR images.
Saving as EXR works for me, can you attach the output EXR image you rendered?

Andrew (cs32) added a subscriber: Andrew (cs32).Dec 13 2022, 8:58 PM

Is this still marked as "Needs information from user" because of issues with his file?
The issue occurs in many ways, and is very easy to reproduce.

Please refer to the attached minimal example file which instead uses an emission shader.
After rendering this in Blender v3.4, it appears fine in the blender render preview, and properly displays the bloom.
When saving to a PNG, though, it clearly loses the transparent bloom edges.

emissive-volume-issue.blend1018 KBDownload

Omar Emara (OmarSquircleArt) added a comment.Dec 14 2022, 8:01 AM

@Andrew (cs32) Your issue is probably just T81199.

M (NeoTrantor) added a subscriber: M (NeoTrantor).Dec 14 2022, 11:26 AM

Same here. Tried PNG, EXR, TIFF, TGA etc. Always the same result.
A a quick & dirty workaround is to put the volumetrics into a separate render layer and fiddle together the (no premultiplied) alpha layers in the compositor.