Having Problems with RTX & CUDA (SketchUp)

[Rusty_Bullitt]

Hi everyone.

Since putting in a new graphics card i'm having problems with RTX & CUDA rendering with complex and/or high resolution images - particularly when using displacement maps. Basically the software either finishes rendering before it's begun, or it crashes the software completely.

I can still render the same scene on the CPU, but it's time consuming and only seems to handle resolution up to 3-4k.

I am using VRay for SketchUp 4.20.01

The graphics card is an EVGA GeForce RTX 2080 Ti

I am currently waiting for a RAM upgrade (currently 16gb) - I don't know if this will help. One error message I get is this..... " failed to create dump file: "(error 183) "

I don't know what the problem is.

I'm not very tech savy so please talk in layman's terms as much as possible.

I really need help with this, trying to find paying work urgently and my hardware / software is letting me down!

[konstantin_chaos]

Hi Rusty_Bullitt,

There are a couple of reasons why this might be happening:

1. Your GPU drivers might have to be updated.
I believe that the 'Finish' before it starts was sometimes caused by that.
So the first thing I'd do is try updating the drivers to the latest version.

2. If SketchUp crashes all together it might be a crash in V-Ray Core.
To test this we'll need a SketchUp scene to test.
An exported .vrscene might also work.
Just make sure to pack all the necessary assets.

3. This might also be a memory issue (GPU or CPU RAM).
The CPU problems that you've faced sound suspicious.
Keep in mind that even though V-Ray GPU (CUDA and RTX) use your graphics card there are still some calculations done on the CPU.
I'd try removing the C++/CPU from the list of GPU devices first.
Another calculation done on the CPU that might be causing trouble is the Light Cache global illumination.
To test this theory, you can go to Settings/Advanced Panel/Global Illumination and select Brute Force from the Secondary Rays menu.

There is some additional information that might help us figure out what's going on:

- What kind of displacement do you use? Is it Normal or 2D?
Keep in mind that in SketchUp it's relatively easy to go overboard with the amount of displaced surfaces in the scene.
The reason is, the displacement is applied to materials (not objects) and it is sometimes hard to keep track of all the displaced surfaces in the scene.
Does disabling displacement help?
To globally disable the effect use the following option: Settings/ Render Parameters/ Switches/ Displacement.

- There is a log that V-Ray creates which might contain some useful information about the crash.
Can you please share this fileas well?
It's located here: %AppData%\Chaos Group\V-Ray for SketchUp
Full path: C:\Users\@user\AppData\Roaming\Chaos Group\V-Ray for SketchUp

As a last note I'd suggest you upgrade V-Ray to the latest version - 4.20.02

Hope that helps,
Konstantin

[Rusty_Bullitt]

Thanks Konstantin, I'll answer point by point.

1. I do have the latest NVIDIA 'Studio' Driver installed. Version 451.48.

2. I can send you the scene, is there a recommended way to easily pack' all the assets? There are a lot of assets in this scene!

3. The CPU was already unticked on the list of GPU devices.
'Brute Force' is already selected.

Additional

- I've been using Normal displacement, what is the difference between normal & 2D?

- Yes, disabling the displacement allows me to GPU render the scene.

- There is a text document in the file location on my C Drive, but it is empty? Or is it the FBS File?

- How can I find the Version Upgrade 4.20.02? I have an annual license paid in March, so I should be able to upgrade without further payment, right?

[konstantin_chaos]

Hi,

1. I do have the latest NVIDIA 'Studio' Driver installed. Version 451.48.

That's great.

2. I can send you the scene, is there a recommended way to easily pack' all the assets? There are a lot of assets in this scene

There are 2 ways to do that:
1. Use Extentions>V-Ray>Pack Project
2. Use the FIle Path Editor to Archive and Repath all the scene assets and archive them together with the skp.

3. The CPU was already unticked on the list of GPU devices.
'Brute Force' is already selected.

That's good, it narrows things down.

- I've been using Normal displacement, what is the difference between normal & 2D?

The two displacement modes use completely different methods in the back.
Each has it's benefits and downsides.
The 3d displacement tends to be slower to generate if you want to use it for small details and is also dependent on the mesh topology of the displaced geometry.
The 2d mode can render very small details extremely quickly but doesn't work with 3d procedural textures and is still not supported on GPU (this will change in V-Ray 5).
The 2d displacement also causes issues when applied to big number of objects. You might experience very long generation before the rendering actually starts in this case.

- Yes, disabling the displacement allows me to GPU render the scene.

This sounds like a memory issue.

- There is a text document in the file location on my C Drive, but it is empty? Or is it the FBS File?

Again, this may be pointing to a memory issues.

- How can I find the Version Upgrade 4.20.02? I have an annual license paid in March, so I should be able to upgrade without further payment, right?

https://download.chaosgroup.com/?lic...201&product=47
It's free. All 'update' and 'hotfix' versions are.
Keep in mind that with your annual license even major version upgrades are.

[Rusty_Bullitt]

Thanks Konstantin, I have sent you a message.

[Rusty_Bullitt]

.....and thank you for your help!

[konstantin_chaos]

Hi,

Thanks for the scene.
I tested it and I can totally reproduce the issue - there is not enough GPU memory for the displacement.
The thing is that you have displacement applied to almost all the objects in the scene and the displacement quality is quite high.
There is an option called Edge Length.
It tells V-Ray to subdivide the mesh until that the longest resulting edge is 4px long (in the image).
Making the image resolution bigger makes things worse since this increases the poly count.

What worked for me is setting all the edge lengths to 12 instead 4.
This way my GPU memory was enough and the quality is reasonable.
I've shared the modified scene in a personal message - SU 2020 / V-Ray 4.20.02

And note that adding RAM to your workstation will not help in this case.
It's the GPU memory which is the problem.
Again, in V-Ray 5 we'll have a slightly different solution for that.

After you optimize the displacement in the scene you can try rendering with Light Cache.
This might speed things up considering it's a closed space.

Otherwise the scene is nicely set up.

Konstantin

[konstantin_chaos]

A script that you can use to set all the edge lengths in the scene:

VRay::LiveScene.active.grep(:GeomDisplacedMesh) { |plugin|
    plugin[:edge_length] = 24
}
VRay.refresh_ui

Change the number 24 to whatever you want and execute the script in the ruby console.

Hope that helps,
Konstantin

[Rusty_Bullitt]

This has been most helpful, thank you!