New Eevee Rendering Volumetrics much Slower than Legacy #125364

New Issue

rohan stevenson · 2024-07-24T11:28:21+02:00

rohan stevenson commented

2024-07-24 11:28:21 +02:00

System Information
Operating system: Linux-6.5.0-44-generic-x86_64-with-glibc2.35 64 Bits, X11 UI
Graphics card: NVIDIA GeForce RTX 4070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 535.183.01

Blender Version
Broken: version: 4.2.0, branch: blender-v4.2-release, commit date: 2024-07-16 06:20, hash: a51f293548ad
Worked: (newest version of Blender that worked as expected)

Short description of error
New Eevee is rendering volumetrics between 15 and 20 times slower than previous versions

Exact steps for others to reproduce the error

Open a file with well a developed scene, lots of objects and textures - moderate, not super heavy but a generous large scale scene.
Add a volumetric cube with a texture and a size of about 400-600m x/y and maybe half to a third on the z axis.
Make a linked copy of the scene and turn everything to hold out in the outliner EXCEPT the volume cube.

In 4.2, Eevee was rendering 1 frame in nearly 40 minutes on the above machine. In 4.1 on a machine less than half as powerful (8-core RTX 2070) it rendered 1 frame in about 1:30. On yet another (8-core RTX 3070) it rendered in about 1:10. I didn't try on this machine in 4.1 but I am guessing it will render a frame in around 50 seconds.

I also tried 4.2 on the smaller computers because they both run Windows, and they also took an infeasibly long time.

On 4.2 it seems that even though objects are held out all the textures are being loaded and then some. I have 64 Gbs of RAM on this computer and 64 Gb swap file and it maxed both. I have 128 Gbs on one of the smaller computer and it made no difference. By contrast, 4.1 Eevee while rendering only loaded 10 Gbs into RAM. I was also able to render the same scene on a 4-core computer with just 16 Gb of RAM with GTX 1080 Ti.

I tried both Ray-Tracing and non-Ray-Tracing mode and it made no difference.

Initially, I was hoping to do the whole scene with Eevee but it quickly started to bog down and it would not reliably render, so I switched back to Cycles and Eevee hybrid method. But even with everything except the volume held out in Eevee it could not handle it in 4.2.

**System Information** Operating system: Linux-6.5.0-44-generic-x86_64-with-glibc2.35 64 Bits, X11 UI Graphics card: NVIDIA GeForce RTX 4070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 535.183.01 **Blender Version** Broken: version: 4.2.0, branch: blender-v4.2-release, commit date: 2024-07-16 06:20, hash: `a51f293548ad` Worked: (newest version of Blender that worked as expected) **Short description of error** New Eevee is rendering volumetrics between 15 and 20 times slower than previous versions **Exact steps for others to reproduce the error** - Open a file with well a developed scene, lots of objects and textures - moderate, not super heavy but a generous large scale scene. - Add a volumetric cube with a texture and a size of about 400-600m x/y and maybe half to a third on the z axis. - Make a linked copy of the scene and turn everything to hold out in the outliner EXCEPT the volume cube. In 4.2, Eevee was rendering 1 frame in nearly 40 minutes on the above machine. In 4.1 on a machine less than half as powerful (8-core RTX 2070) it rendered 1 frame in about 1:30. On yet another (8-core RTX 3070) it rendered in about 1:10. I didn't try on this machine in 4.1 but I am guessing it will render a frame in around 50 seconds. I also tried 4.2 on the smaller computers because they both run Windows, and they also took an infeasibly long time. On 4.2 it seems that even though objects are held out all the textures are being loaded and then some. I have 64 Gbs of RAM on this computer and 64 Gb swap file and it maxed both. I have 128 Gbs on one of the smaller computer and it made no difference. By contrast, 4.1 Eevee while rendering only loaded 10 Gbs into RAM. I was also able to render the same scene on a 4-core computer with just 16 Gb of RAM with GTX 1080 Ti. I tried both Ray-Tracing and non-Ray-Tracing mode and it made no difference. Initially, I was hoping to do the whole scene with Eevee but it quickly started to bog down and it would not reliably render, so I switched back to Cycles and Eevee hybrid method. But even with everything except the volume held out in Eevee it could not handle it in 4.2.

Screenshot from 2024-07-23 17-00-22.png

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rohan stevenson added the

labels 2024-07-24 11:28:22 +02:00

Pratik Borhade commented

2024-07-31 11:23:45 +02:00

Hi, thanks for the report. Can you attach the simplified .blend file for comparison? Performance impact is likely expected due to ray tracing and a few newer features but there would be a way to improve the performance after few tweaks in render properties.

Pratik Borhade added

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Needs Information from User

and removed

Status

Needs Triage

labels 2024-07-31 11:23:55 +02:00

rohan stevenson commented

2024-07-31 13:27:01 +02:00

Hi, thanks for the report. Can you attach the simplified .blend file for comparison? Performance impact is likely expected due to ray tracing and a few newer features but there would be a way to improve the performance after few tweaks in render properties.

I thought you might ask for this. The .blend files I am working with are too large to send to you but I will if you insist.

I am finding the problem consistent though so if I get time later today I will try with a simplified file with the volume cube.

It does NOT seem to be related to ray-tracing. I thought that as well, but turning it off makes no difference.

Could I suggest simply opening any medium size project (enough geometry and textures) and then putting a volume cube of around 300 metres square and 50-100 metres high? Create a misty foggy ambience. That would be faster and easier than my sending a project. If you can't seem to replicate my problems then I'll send a project.

My final thoughts: I have always found Eevee to use an extraordinary amount of memory even when only rendering volumes with the main scene held out (no textures). I have gotten around this with very large swap files and a smaller machine with 128Gbs of RAM. Eevee often loads anything up to and over 10 times the actual file size. But Eevee-Next is next level. Even with a small scene with a rowing boat, a ship and an ocean its using something like 96 Gb of memory. Crazy.

> Hi, thanks for the report. Can you attach the simplified .blend file for comparison? Performance impact is likely expected due to ray tracing and a few newer features but there would be a way to improve the performance after few tweaks in render properties. I thought you might ask for this. The .blend files I am working with are too large to send to you but I will if you insist. I am finding the problem consistent though so if I get time later today I will try with a simplified file with the volume cube. It does NOT seem to be related to ray-tracing. I thought that as well, but turning it off makes no difference. Could I suggest simply opening any medium size project (enough geometry and textures) and then putting a volume cube of around 300 metres square and 50-100 metres high? Create a misty foggy ambience. That would be faster and easier than my sending a project. If you can't seem to replicate my problems then I'll send a project. My final thoughts: I have always found Eevee to use an extraordinary amount of memory even when only rendering volumes with the main scene held out (no textures). I have gotten around this with very large swap files and a smaller machine with 128Gbs of RAM. Eevee often loads anything up to and over 10 times the actual file size. But Eevee-Next is next level. Even with a small scene with a rowing boat, a ship and an ocean its using something like 96 Gb of memory. Crazy.

Pratik Borhade added

Status

Needs Triage

and removed

Status

Needs Information from User

labels 2024-08-09 12:01:48 +02:00

Bart van der Braak added

and removed

labels 2024-08-14 12:55:03 +02:00

Pratik Borhade commented

2024-09-11 09:02:57 +02:00

Hi, a simple .blend would still help to speed up the investigation. Not much can be done without a reference file in which the performance difference can be observed.

Pratik Borhade added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2024-09-11 09:03:06 +02:00

Pratik Borhade commented

2024-09-11 09:03:29 +02:00

Also check recent 4.2.1/4.3 build: https://builder.blender.org/download/daily/