Introduction
V-Ray GPU offers fast interactive feedback for look development and final rendering. Faster iterations free up time to explore ideas, boost productivity, and produce better results. This article presents the workflow of interactive rendering in V-Ray GPU, along with some valuable tips to help you maximize your hardware's performance.
Settings overview
Settings to control interactive rendering can be located in the IPR tab of the Render Settings.
- IPR Rays Per Pixel (value range from 1 to 8 ) - the number of rays that are traced per pixel for one image pass. The higher the value, the smoother the image will be, plus it increases GPU usage on high-end cards like the RTX 3090.
- IPR Ray bundle size (value range from 128 to 512) - controls the number of rays processed together in a bundle during interactive rendering.
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Undersampling (value range = 0 to 4) - controls the initial sampling rate of the image. If set higher than zero, V-Ray renders the image at a lower resolution to speed up the initial preview.
Where to find the IPR tab:
Recommended settings
Below are presented ready-to-use presets for a variety of hardware configurations, based on internal testing, to ensure optimal performance and GPU usage. The 'Undersampling' value is a matter of personal preference, so feel free to experiment with it.
Preset for high-end GPUs (RTX 3090 and RTX 4090):
- Rays Per Pixel 4
- Ray Bundle Size 256
- Undersampling 2
Preset for mid-range GPUs (RTX 3060, RTX 2080ti):
- Rays Per Pixel 2
- Ray Bundle Size 256
- Undersampling 2
Preset for low-end GPUs (RTX 1080, RTX 2060 Super):
- Rays Per Pixel 1
- Ray Bundle Size 128
- Undersampling 2
Preset for multiple high-end GPUs:
- Rays Per Pixel to 8
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Ray Bundle Size to 512
Using NVIDIA AI Denoiser with interactive rendering
The NVidia AI Denoiser uses AI to guess what the image should look like without the noise. It works well with high-frequency noise in early passes of interactive rendering, calculates super fast on the GPU, and suits interactive rendering perfectly.
As of V-Ray 6, you are able to pick a dedicated device for denoising. When having multiple GPU, this improves the interactive performance as well as GPU memory usage as denoising happens on a separate device.
You can choose which device does the denoising through the Maya UI or the standalone Device Select tool.
Learn more in our article about How to use the GPU Device Select tool in V-Ray.
Note that NVIDIA AI Denoiser is not consistent when denoising render elements if used for final rendering. This means that there will be differences between the original RGB image and the one reconstructed from render elements that are denoised with the NVIDIA AI Denoiser. It also doesn’t support cross-frame denoising and will likely produce flickering when used in animation.
For final rendering, it is recommended to switch to V-Ray or Intel’s Denoisers.
Workflow for Interactive rendering in V-Ray GPU
- Add the V-Ray Denoiser Render Element/Channel or activate the Denoiser
- In Maya: Render Settings > Render Elements > Denoiser
- In Houdini: V-Ray Render Elements node > V-Ray > Render Channel > V-Ray Denoiser (RE)
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In Cinema4D: Render Setup > Common tab > Denoiser
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Set the engine to "NVidia AI Denoiser"
Note: In V-Ray for Maya, you can set an Engine for IPR rendering and different one for final rendering.
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Set the Denoiser update frequency by using the Post Effect Rate/Image Effects Update Freq.:
For high-end GPUs (RTX 3090 and RTX 4090): 100
For mid-range GPUs (RTX 3060, RTX 2080ti): 50-75
For low-end GPUs (RTX 1080, RTX 2060 Super): 10-50
A value of 100 means that the denoiser will update as frequently as possible; a value of 0 will disable updates.
Where to find the setting:
For final rendering, if you are using Progressive mode, you will need to set Post Effects Rate to 0 for optimal performance. You don’t want the Denoiser to update every second.
- Set the IPR Rays Per Pixel and IPR Ray Bundle Size from the presets above
- Set the Max. Noise based on personal preference
Preview of the settings in action with a high-end GPU preset for the RTX 4090.
Use of GPU Light Cache in interactive rendering
By default, V-Ray uses the BF/BF GI engines for interactive rendering. For interior scenes, however, where illumination relies on indirect lighting, it is recommended to enable the Light Cache in IPR option.
Although it reduces interactivity, as it must be calculated for every change or camera movement, it gives more accurate lighting and produces less noise.
It is recommended to use values between 750 to 1500 for GPU LC Subdivs for interactive rendering. This will improve GPU LC performance and overall responsiveness for interactive rendering. For final rendering, you can increase the value to 2000-3000.
Where to find the setting: