Volume overlap clipping #111434

New Issue

Richard Traynor · 2023-08-23T15:50:52+02:00

Richard Traynor commented

2023-08-23 15:50:52 +02:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 536.40

Blender Version
Broken: version: 3.6.2, branch: blender-v3.6-release, commit date: 2023-08-16 16:43, hash: e53e55951e7a
Worked: (newest version of Blender that worked as expected)

Short description of error

Overlapping VDB/Volume objects create clipping issues where empty space of one volume meets another volume. Changing VDB space from Object to world does not address this issue, neither does changing the float precision from from half to full. Neither does increasing the volume steps, volume light bounces, or the transparency light bounces.

This has been a consistent issue now since maybe as far back as 2.79, then it could be mitigated by the "optimise empty space" being disabled, but now that's seemingly gone, the issue is back and really needs addressing.

Exact steps for others to reproduce the error

Open the attached Blend file
head into rendered viewport.

You will see clipping like in the images attached
Alternatively, just add a vdb or volume bake to a scene and instance it or duplicate it to overlap with one another and in Cycles you will see the clipping happen

Download from this link NEW LINK

Thank you for looking into this

EDIT: Updated link

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 536.40 **Blender Version** Broken: version: 3.6.2, branch: blender-v3.6-release, commit date: 2023-08-16 16:43, hash: `e53e55951e7a` Worked: (newest version of Blender that worked as expected) **Short description of error** <tr> <img src="/attachments/6c7b6136-054f-4f19-9e96-021d74ca1705" alt="Snag_a8e98af" height=400px></td> <img src="/attachments/34e509be-aeeb-4d86-9104-7f85d1b887b8" alt="Snag_a8e98af" height=400px></td> </tr> Overlapping VDB/Volume objects create clipping issues where empty space of one volume meets another volume. Changing VDB space from Object to world does not address this issue, neither does changing the float precision from from half to full. Neither does increasing the volume steps, volume light bounces, or the transparency light bounces. This has been a consistent issue now since maybe as far back as 2.79, then it could be mitigated by the "optimise empty space" being disabled, but now that's seemingly gone, the issue is back and really needs addressing. **Exact steps for others to reproduce the error** - Open the attached Blend file - head into rendered viewport. You will see clipping like in the images attached Alternatively, just add a vdb or volume bake to a scene and instance it or duplicate it to overlap with one another and in Cycles you will see the clipping happen Download from this link [NEW LINK](https://hub.true-vfx.xyz/s/p6qN69KLpCFbMHc) Thank you for looking into this EDIT: Updated link

Snag_a8e98af.png

1.9 MiB

Snag_a8adafb.png

1.5 MiB

👍 1

Richard Traynor added the

labels 2023-08-23 15:50:52 +02:00

Richard Traynor commented

2023-08-23 16:05:43 +02:00

For some reason the site is not allowing me to attach the file, it's under 500mb at 377mb, I'm attempting to attach again via this comment EDIT: welp, no. Seems like it uploads, and gives me the green light but then simply does not appear when I click comment
2nd EDIT: Download from this link UPDATED LINK

For some reason the site is not allowing me to attach the file, it's under 500mb at 377mb, I'm attempting to attach again via this comment EDIT: welp, no. Seems like it uploads, and gives me the green light but then simply does not appear when I click comment 2nd EDIT: Download from this link [UPDATED LINK](https://hub.true-vfx.xyz/s/p6qN69KLpCFbMHc)

Germano Cavalcante commented

2023-08-23 21:55:22 +02:00

Thanks for the report, @True-VFX.

This bug report could potentially be related to:
#107418: Visible density seen inside an overlapping volume with zero density value (Cycles).
#105549: Render issues when two VBD overlap if rendered with motion blur.

Unfortunately we don't have the necessary VDB files to see the issue.

VDB files are not packed along with Blender, so the attached file is missing them. And it's big (0.4GB) because of the 4k textures included.

Could you provide a simplified file showing the problem?

Also make sure it's not some setting that's causing the problem (like the amount of transparency bounces).

Thanks for the report, @True-VFX. This bug report could potentially be related to: #107418: Visible density seen inside an overlapping volume with zero density value (Cycles). #105549: Render issues when two VBD overlap if rendered with motion blur. Unfortunately we don't have the necessary VDB files to see the issue. VDB files are not packed along with Blender, so the attached file is missing them. And it's big (0.4GB) because of the 4k textures included. Could you provide a simplified file showing the problem? Also make sure it's not some setting that's causing the problem (like the amount of transparency bounces).

Germano Cavalcante added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2023-08-23 21:55:32 +02:00

Marc-Whitelaw commented

2023-08-23 22:26:13 +02:00

Hi Germano,

Thanks for the reply. I am experiencing this issue too. From my experience the issue is coming from VDB's that have been scaled up or down within Blender. I think there might be a problem with the way Blender scales VDB's.

I will create a test scene and upload here when I can.

Hi Germano, Thanks for the reply. I am experiencing this issue too. From my experience the issue is coming from VDB's that have been scaled up or down within Blender. I think there might be a problem with the way Blender scales VDB's. I will create a test scene and upload here when I can.

Samuel-A-Krug commented

2023-08-23 22:58:59 +02:00

I don't have much to add here other than the fact that clouds (and Volumetrics in general) seem to be something that cycles otherwise excels at, and this is glitch makes it near unusable in many scenarios.

I included a few renders at the bottom with an example of this issue. In the bottom middle on the left render you can see the blocky artifacts appearing, and in the right they have been photo-shopped out. This was fine for a still, but for animations (which I was originally trying to do here) this would have made it unusable. Marc (who made the comment above mine) does a fair bit more work with animations than I do, and has experienced these issues a fair few times.

It's useful to note that many artists are switching to Cycles (Marc included) from renderers like Redshift, Octane and Arnold particularly because Cycles handles clouds and such so much better. This is a rather large roadblock for us, and we definitely need at least a solution.

Thank you all!
Sam

I don't have much to add here other than the fact that clouds (and Volumetrics in general) seem to be something that cycles otherwise excels at, and this is glitch makes it near unusable in many scenarios. I included a few renders at the bottom with an example of this issue. In the bottom middle on the left render you can see the blocky artifacts appearing, and in the right they have been photo-shopped out. This was fine for a still, but for animations (which I was originally trying to do here) this would have made it unusable. Marc (who made the comment above mine) does a fair bit more work with animations than I do, and has experienced these issues a fair few times. It's useful to note that many artists are switching to Cycles (Marc included) from renderers like Redshift, Octane and Arnold particularly because Cycles handles clouds and such so much better. This is a rather large roadblock for us, and we definitely need at least *a* solution. Thank you all! Sam

CloudEnv1.png

2.6 MiB

CloudEnv1_0-00-00-00.png

2.8 MiB

Richard Traynor commented

2023-08-23 23:12:40 +02:00

Thanks for the report, @True-VFX.

This bug report could potentially be related to:
#107418: Visible density seen inside an overlapping volume with zero density value (Cycles).
#105549: Render issues when two VBD overlap if rendered with motion blur.

Unfortunately we don't have the necessary VDB files to see the issue.

VDB files are not packed along with Blender, so the attached file is missing them. And it's big (0.4GB) because of the 4k textures included.

Could you provide a simplified file showing the problem?

Also make sure it's not some setting that's causing the problem (like the amount of transparency bounces).

I have fixed the downloaded file. Seems that VDBs will pack and bloat the blend file, but will not actually be present. Unpacked the file and added to a link here which you will need to download and unzip NEW LINK

> Thanks for the report, @True-VFX. > > This bug report could potentially be related to: > #107418: Visible density seen inside an overlapping volume with zero density value (Cycles). > #105549: Render issues when two VBD overlap if rendered with motion blur. > > Unfortunately we don't have the necessary VDB files to see the issue. > > VDB files are not packed along with Blender, so the attached file is missing them. And it's big (0.4GB) because of the 4k textures included. > > Could you provide a simplified file showing the problem? > > Also make sure it's not some setting that's causing the problem (like the amount of transparency bounces). > > > > I have fixed the downloaded file. Seems that VDBs will pack and bloat the blend file, but will not actually be present. Unpacked the file and added to a link here which you will need to download and unzip [NEW LINK](https://hub.true-vfx.xyz/s/p6qN69KLpCFbMHc)

Marc-Whitelaw commented

2023-08-24 00:48:46 +02:00

Hello again Just uploading an animation test I ran out last week which highlights the issue.
I will do a more dedicated test as soon as I have time.

Just to echo what Samuel was saying. Cycles is amazing at rendering volumes. I have used Arnold, Mantra, Karma and just switched from Redshift purely because Blender Cycles is the best I have used so far. Fixing this overlapping vdb issue is a big concern for many people and hopefully we can isolate the cause and rectify it.

It appears that keeping the scale at 1 of the vdb's just minimizes the clipping issue but doesn't solve it.

I am in the middle of a big project so will try find some time to do a dedicated test to share here.

Really hoping we can escalate this issue as it would be greatly beneficial to the community.

Chat soon

Hello again Just uploading an animation test I ran out last week which highlights the issue. I will do a more dedicated test as soon as I have time. Just to echo what Samuel was saying. Cycles is amazing at rendering volumes. I have used Arnold, Mantra, Karma and just switched from Redshift purely because Blender Cycles is the best I have used so far. Fixing this overlapping vdb issue is a big concern for many people and hopefully we can isolate the cause and rectify it. It appears that keeping the scale at 1 of the vdb's just minimizes the clipping issue but doesn't solve it. I am in the middle of a big project so will try find some time to do a dedicated test to share here. Really hoping we can escalate this issue as it would be greatly beneficial to the community. Chat soon

byc_vdb_debug_v02.mp4

9.9 MiB

byc_vdb_debug_v01_0120.jpg

1012 KiB

Germano Cavalcante added

Status

Needs Triage

and removed

Status

Needs Information from User

labels 2023-08-24 00:51:27 +02:00

Pratik Borhade commented

2023-08-24 05:38:57 +02:00

Hi, thanks for the report. I can confirm in uploaded file.
Similar artifacts has been observed before due to possibly same or different reasons. (#97094, #96153, #83604, #79762)
@brecht @Sergey , can you check?

Hi, thanks for the report. I can confirm in uploaded file. Similar artifacts has been observed before due to possibly same or different reasons. (#97094, #96153, #83604, #79762) @brecht @Sergey , can you check?

Pratik Borhade added

Module

Render & Cycles

Status

Needs Info from Developers

and removed

Status

Needs Triage

labels 2023-08-24 05:39:15 +02:00

Sergey Sharybin commented

2023-08-24 10:03:21 +02:00

The link in the description seems to be broken, so i used the link from this comment #111434 (comment)

I can not reproduce the issue on Apple M2, and on NVidia GP100. I don't currently have machine with Ada, so will take a bit to test that.

Just to confirm: is the issue here only happens on GPU and not CPU?

The link in the description seems to be broken, so i used the link from this comment https://projects.blender.org/blender/blender/issues/111434#issuecomment-1004981 I can not reproduce the issue on Apple M2, and on NVidia GP100. I don't currently have machine with Ada, so will take a bit to test that. Just to confirm: is the issue here only happens on GPU and not CPU?

Pratik Borhade commented

2023-08-24 11:41:20 +02:00

I can reproduce artifacts on both CPU and GPU. But they are less visible in CPU render

**System Information**
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3050 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 532.03
Blender version: 4.0, 6e20beba22df

I can reproduce artifacts on both CPU and GPU. But they are less visible in CPU render ``` **System Information** Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3050 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 532.03 Blender version: 4.0, 6e20beba22df ```

Richard Traynor commented

2023-08-24 13:51:48 +02:00

In this particular case, the issue is present in Optix. I have attached images below using different render devices (I have tested optix with GPU+CPU and this doesn't mitigate the issue)

Snag_f4a5eeb.png

463 KiB

Snag_f4a791a.png

495 KiB

Snag_f4a6b9d.png

561 KiB

Marc-Whitelaw commented

2023-08-24 23:59:16 +02:00

I ran a test with an animated vdb (Houdini simulation) and while using Cuda there were still artifacts present when rendering with GPU. Never tested CPU though but ultimately for time constraints GPU is always preferred.

Pratik Borhade referenced this issue

2023-09-25 05:40:48 +02:00

vdb still showing blocky artefacts #112778

Sebastien Larocque commented

2023-10-02 02:44:24 +02:00

I’ve just updated my original bug report on a similar topic to this one. I’m writing here to invite you to look at it as it probably demonstrates the cause of the problem or a part of it.

I ran an extensive and very detailed test. Originally, I had written about overlapping volumes creating artifacts. In my new test, I discovered that non-overlapping volumes also have artifacts, but are only visible in particular cases.

I believe it is related to this report and developers should look at it in connection with this report here as it provides a new perspective and elements to understand the strange artifacts in volumes.

My new post is on October 1, 2023.
#107418 (comment)

I’ve just updated my original bug report on a similar topic to this one. I’m writing here to invite you to look at it as it probably demonstrates the cause of the problem or a part of it. I ran an extensive and very detailed test. Originally, I had written about overlapping volumes creating artifacts. In my new test, I discovered that non-overlapping volumes also have artifacts, but are only visible in particular cases. I believe it is related to this report and developers should look at it in connection with this report here as it provides a new perspective and elements to understand the strange artifacts in volumes. My new post is on October 1, 2023. https://projects.blender.org/blender/blender/issues/107418#issuecomment-1035101

Samuel-A-Krug commented

2023-10-02 03:33:43 +02:00

@SebBlender I just looked through it, thanks for the addition. As a fellow professional, this definitely is a headache.

👍 1

Lukas Stockner commented

2023-10-05 02:15:53 +02:00

The download link here seems dead again, does someone still have the file?

In any case, there appear to be at least three open "overlapping volumes cause artifacts" tickets where the issue is that the boundary geometry of the domain is exactly overlapping. Could you check whether that is the case here (e.g. by simply moving each volume by a random tiny amount in all three directions)?

The download link here seems dead again, does someone still have the file? In any case, there appear to be at least three open "overlapping volumes cause artifacts" tickets where the issue is that the boundary geometry of the domain is exactly overlapping. Could you check whether that is the case here (e.g. by simply moving each volume by a random tiny amount in **all three directions**)?

Pratik Borhade referenced this issue

2024-02-01 06:44:32 +01:00

Volumetric rendering not working with Boolean difference, when using Shade Smooth #117692

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Volume overlap clipping #111434