Eevee volume shader on imported VDB influences other volumetrics density (specified density attribute makes a difference) #84541

New Issue

Andrew Walsh · 2021-01-08T22:00:40+01:00

Andrew Walsh commented

2021-01-08 22:00:40 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 457.51

Blender Version
Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: 0f45cab862
Worked: (newest version of Blender that worked as expected)

Short description of error
I've noticed for a while now that if I bring in a vdb file, to a scene that already has fog via a large cube with principled volume shader applied, once I either import the vdb or, if it's hidden and I unhide it, the scene fog via the large cube will suddenly turn off. There's no way to get it back other than to reload the scene/restart Blender.

Exact steps for others to reproduce the error
Make a scene, envelop it in a large cube, apply principled volume shader. Something like 0.025 density or thereabouts. Whatever is thick enough to see the scene and appreciate the fog is there.
Import a vdb file and apply a volume shader to it. The main fog should disappear.
Then try putting the fog on the cube up to 1.0 density and you'll notice you get fog back, but, it's not as dense as it should be, even at 1.0 density.

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 457.51 **Blender Version** Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: `0f45cab862` Worked: (newest version of Blender that worked as expected) **Short description of error** I've noticed for a while now that if I bring in a vdb file, to a scene that already has fog via a large cube with principled volume shader applied, once I either import the vdb or, if it's hidden and I unhide it, the scene fog via the large cube will suddenly turn off. There's no way to get it back other than to reload the scene/restart Blender. **Exact steps for others to reproduce the error** Make a scene, envelop it in a large cube, apply principled volume shader. Something like 0.025 density or thereabouts. Whatever is thick enough to see the scene and appreciate the fog is there. Import a vdb file and apply a volume shader to it. The main fog should disappear. Then try putting the fog on the cube up to 1.0 density and you'll notice you get fog back, but, it's not as dense as it should be, even at 1.0 density.

Andrew Walsh commented

2021-01-08 22:00:40 +01:00

Added subscriber: @andywalshart

Robert Guetzkow commented

2021-01-09 10:54:49 +01:00

Added subscriber: @rjg

Robert Guetzkow commented

2021-01-09 10:54:49 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Robert Guetzkow commented

2021-01-09 10:54:49 +01:00

In what viewport shading mode and with which render engine are you viewing these volumetrics? In my test using the smoke1.vdb provided on the OpenVDB website , I couldn't reproduce the problem. Can you please share a*minimal// example file that demonstrates the issue or provide more detailed instructions? Overlapping volumes in Cycles can cause artifacts, see #83604.

Does this file work properly for you?

T84541_intersecting_volumes.blend

In what viewport shading mode and with which render engine are you viewing these volumetrics? In my test using the `smoke1.vdb` provided on the [OpenVDB website ](https:*www.openvdb.org/download/), I couldn't reproduce the problem. Can you please share a*minimal// example file that demonstrates the issue or provide more detailed instructions? Overlapping volumes in Cycles can cause artifacts, see #83604. Does this file work properly for you? [T84541_intersecting_volumes.blend](https://archive.blender.org/developer/F9556997/T84541_intersecting_volumes.blend)

Andrew Walsh commented

2021-01-09 11:16:37 +01:00

smoke-test.blend

Try this. There's a cube in the scene with fog density set to 1.0 so you can't see anything. Look in the scene collections for the vdb file which is currently hidden. Unhide it and the fog will reduce in density visibly but will still be at 1.0

[smoke-test.blend](https://archive.blender.org/developer/F9557000/smoke-test.blend) Try this. There's a cube in the scene with fog density set to 1.0 so you can't see anything. Look in the scene collections for the vdb file which is currently hidden. Unhide it and the fog will reduce in density visibly but will still be at 1.0

Robert Guetzkow commented

2021-01-09 13:33:24 +01:00

If I open the file you've provided I see no difference in material preview or rendered mode with or without the vdb object being visible. Please answer the questions from my last comment and provide precise instructions how to reproduce the problem with the file you've provided.

If I open the file you've provided I see no difference in material preview or rendered mode with or without the vdb object being visible. Please answer the questions from my last comment and provide *precise* instructions how to reproduce the problem with the file you've provided.

Andrew Walsh commented

2021-01-09 15:47:21 +01:00

2021-01-09_14-38-16.mp4

I uploaded a video to show how it looks for me. Unfortunately the audio didn't capture but if you just re-read what I said above it's about as precise as it needs to be. In the video I open the file, note that there's nothing visible in the scene because the fog density of the shader (that's applied to a cube encompassing the scene) is set to 1.0. I unhide the vdb file and it erroneously causes the fog density to change, so now, once the vdb file is unhidden, we CAN see the scene. However, the density has not changed from 1.0. At the end of the video I re-load the file and it's still broken (the volumetric fog is neither 0 or 1, it's somewhere in between). You have to restart Blender to fix it. Using Eevee.

[2021-01-09_14-38-16.mp4](https://archive.blender.org/developer/F9557142/2021-01-09_14-38-16.mp4) I uploaded a video to show how it looks for me. Unfortunately the audio didn't capture but if you just re-read what I said above it's about as precise as it needs to be. In the video I open the file, note that there's nothing visible in the scene because the fog density of the shader (that's applied to a cube encompassing the scene) is set to 1.0. I unhide the vdb file and it erroneously causes the fog density to change, so now, once the vdb file is unhidden, we CAN see the scene. However, the density has not changed from 1.0. At the end of the video I re-load the file and it's still broken (the volumetric fog is neither 0 or 1, it's somewhere in between). You have to restart Blender to fix it. Using Eevee.

Robert Guetzkow commented

2021-01-09 15:51:21 +01:00

I can't reproduce this in Blender 2.91 or the current master branch.

Andrew Walsh commented

2021-01-09 16:09:27 +01:00

2021-01-09_15-02-36.mp4
smoke-test-new.blend
Round_Clouds.0032.vdb

Watch the attached video. Open the new Blender file and do what I do in the video. I've attached the vdb file. Essentially import the vdb cloud file, add the default volumetric shader and then scale it up and down and watch the density of the large cube's volumetric shader go in and out in proportion to the vdb file. It's a scaling issue of some kind related to some aspect of certain vdb files.

[2021-01-09_15-02-36.mp4](https://archive.blender.org/developer/F9557166/2021-01-09_15-02-36.mp4) [smoke-test-new.blend](https://archive.blender.org/developer/F9557172/smoke-test-new.blend) [Round_Clouds.0032.vdb](https://archive.blender.org/developer/F9557174/Round_Clouds.0032.vdb) Watch the attached video. Open the new Blender file and do what I do in the video. I've attached the vdb file. Essentially import the vdb cloud file, add the default volumetric shader and then scale it up and down and watch the density of the large cube's volumetric shader go in and out in proportion to the vdb file. It's a scaling issue of some kind related to some aspect of certain vdb files.

Robert Guetzkow commented

2021-01-09 20:32:31 +01:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Robert Guetzkow commented

2021-01-09 20:32:31 +01:00

Yes, I've seen the previous video and done the same steps. I will take a look at your new files and video on Monday, but it seems that I cannot reproduce the issue on my system.

Philipp Oeser commented

2021-02-01 18:45:44 +01:00

Added subscribers: @fclem, @lichtwerk

Philipp Oeser commented

2021-02-01 18:45:44 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2021-02-01 18:45:44 +01:00

Seems I can reproduce.

As soon as some attribute is specified (doesnt even make a difference which one, non-existent or whatever) in the Cube's Principled Volume shaders's Density Attribute, its density is influenced by other volume shaders.

@fclem: this cant be expected behavior, right?

Seems I can reproduce. As soon as some attribute is specified (doesnt even make a difference which one, non-existent or whatever) in the Cube's `Principled Volume` shaders's `Density Attribute`, its density is influenced by other volume shaders. @fclem: this cant be expected behavior, right?

Philipp Oeser changed title from ~~importing a VDB makes scene volumetrics disappear~~ to Eevee volume shader on imported VDB influences other volumetrics density (specified density attribute makes a difference)

2021-02-01 18:47:33 +01:00

Andrew Walsh commented

2021-04-09 17:50:58 +02:00

any news on this issue? can confirm it's still doing it in 2.92.0
Would appreciate someone helping me work through this. I've just permanently broke a scene that I've been working on for a few weeks because I imported a VDB file and it's stopping normal volumetrics from working at all.

edit: I think it re-scales the volumetrics in the scene. I thought volumes weren't working as it looked identical to being turned off. But I increased the density from 0.015 to 0.5 and it now looks roughly the same as it was before I imported the vdb file.

any news on this issue? can confirm it's still doing it in 2.92.0 Would appreciate someone helping me work through this. I've just permanently broke a scene that I've been working on for a few weeks because I imported a VDB file and it's stopping normal volumetrics from working at all. edit: I think it re-scales the volumetrics in the scene. I thought volumes weren't working as it looked identical to being turned off. But I increased the density from 0.015 to 0.5 and it now looks roughly the same as it was before I imported the vdb file.

Andrew Walsh commented

2021-04-09 20:22:50 +02:00

2021-04-09 19-20-03.mkv

Not sure if I've sent a video of the issue before but here's a video of me scaling a vdb file and like a dimmer switch, it's scale is directly affecting the cube of volume in the scene. (the cube just has a standard volumetric shader to give it some atmos).

Oops, yes I see above that I already sent such a thing. Apologies.

[2021-04-09 19-20-03.mkv](https://archive.blender.org/developer/F9927031/2021-04-09_19-20-03.mkv) Not sure if I've sent a video of the issue before but here's a video of me scaling a vdb file and like a dimmer switch, it's scale is directly affecting the cube of volume in the scene. (the cube just has a standard volumetric shader to give it some atmos). Oops, yes I see above that I already sent such a thing. Apologies.

Andrew Walsh commented

2022-02-22 14:36:02 +01:00

This is still present in 3.0.1
renders in cycles but, in Eevee, an imported vdb file turns off volume fog (when applied to a cube with principled volume shader applied).

This is still present in 3.0.1 renders in cycles but, in Eevee, an imported vdb file turns off volume fog (when applied to a cube with principled volume shader applied).

Philipp Oeser removed the

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Eevee volume shader on imported VDB influences other volumetrics density (specified density attribute makes a difference) #84541