2 newbie questions if I may?

[jon_leeke]

1, When rendering a final production image, using V-Ray GPU engine, CUDA or RTX, I've tried both, V-Ray only seems to utilize a small percentage of my GPU's power. Is this normal?

For example during the render:

CUDA - 100% CPU Utilization - only 5% GPU Utilization

RTX - 4% CPU Utilization - 17% GPU Utilization

When using CUDA, is there a reason it only uses a small amount of GPU contribution and in RTX is there a reason it's not using 100% GPU? Is there a way to assign more use from the GPU?

(NVIDIA GeForce RTX 3090)

2, Saving an output render. Here I believe we have 2 options, using V-Ray output system and the native C4D save. If I use the native C4D method the saved image is exactly as it appears in the VFB (as desired), however if I use the V-Ray output system the saved image is not the same as the VFB it comes out darker. Its the same result if I save an image out of the VFB, the saved image is darker than in the buffer. Does anyone know how I output an image that will appear exactly as it does in the VFB?

Thanks in advance

[sirio76]

Don't know about question 1, it can be a number of things, you can try to install the suggested drivers and check your VRAM usage.
Regarding question 2, by default you should get 100% the same results between what you see in the VFB (or save from Vray output) and what you get in PS, if that's not the case maybe you need to restore your PS (or other editing software) color management settings. If you are using a LUT don't forget to select the save in image option.

[jon_leeke]

Yeah I figure it should give the same result but some reason it doesn't. If you take a look at the screen shot, the centre render region if within the VFB, the right is that region saved as a 16bit Tiff saved through C4D (when opened in Photoshop both appear the same) the left however is saved using the V-Ray output system again 16bit Tiff but when opened in Photoshop you can see its darker and duller. No LUT used in this one.

[sirio76]

What happens if you save in 8bit?

[jon_leeke]

The same in 8bit. I'd just use the C4D output however it doesn't seem to apply all of the adjustment layers eg bloom and glare.
I'm sure there is something obvious I'm doing incorrectly but I cant find it!

[sirio76]

If you are using default setting in both C4D and Vray all should work perfectly, if it’s not working then better to open a ticket with the support and share a scene with them.

[jon_leeke]

Thank you, I'll do that. FYI I just updated to V-Ray 6 and still have the same issue

Thanks for your help

[jon_leeke]

I've figured the issue with differing output images tones. In my display correction I had my exposure set to 1 not default of 0 hence the difference in output appearance over VFB appearance. Told you it was a newbie issue

[aleksandar.kasabov]

Hello jon_leeke,

I am glad to hear that you managed to find a solution to this issue. As per the first question:

1, When rendering a final production image, using V-Ray GPU engine, CUDA or RTX, I've tried both, V-Ray only seems to utilize a small percentage of my GPU's power. Is this normal?

For example during the render:

CUDA - 100% CPU Utilization - only 5% GPU Utilization

RTX - 4% CPU Utilization - 17% GPU Utilization

When using CUDA, is there a reason it only uses a small amount of GPU contribution and in RTX is there a reason it's not using 100% GPU? Is there a way to assign more use from the GPU?

Are you monitoring the GPU usage in the Performance tab of the Task manager? If that is the case, please note that it usually doesn't display the correct usage of the GPU. Can you download an external tool (such as GPU-Z) and monitor your usage there? Please let me know what GPU usage you get there. Thank you.

[jon_leeke]

Yes you are right, I totally missed that. Thank you. In my Task Manager, Performance if I change one of the dropdowns to CUDA I can see my graphics card is being used 100% during a render. Strange that Windows shows overall utilization differently