Rendering with V-Ray GPU

This page provides information on rendering with V-Ray GPU.

Overview

Rendering with V-Ray GPU performs the raytracing calculations on the GPUs installed in the system, rather than the CPU (both GPUs and the CPU are used in CUDA mode). Since GPUs are specifically designed for massively parallel calculations, they can speed up the rendering process by an order of magnitude.

To enable GPU rendering, go to Render Properties (with the V-Ray Render Engine selected) and set the V-Ray Engine to GPU. You can select which GPUs (if multiple) to use or whether CUDA mode utilizes the CPU. This is done by clicking on the Devices button, which opens the V-Ray Preferences.

V-Ray GPU can be used with both Progressive and Bucket Sampler types.

Supported Hardware and Drivers

V-Ray GPU renders with the NVIDIA CUDA and RTX platforms.

Below is a list of tests we have performed and the results:

• NVIDIA – When the engine is set to V-Ray GPU (with RTX disabled), the CUDA platform is used. It is supported only in 64-bit builds of V-Ray for Maxwell and later NVIDIA cards. See here if your card has the minimum required computing capability.
• NVIDIA RTX – When the engine is set to V-Ray GPU with RTX enabled, V-Ray GPU uses the RT Cores in NVIDIA RTX GPUs.
• Hybrid Rendering (running CUDA on GPU and CPU): V-Ray GPU CUDA rendering can be performed on CPUs and NVIDIA GPUs at the same time. Using Rendering Devices, you can enable your CPUs as CUDA devices and allow the CUDA code to combine your CPUs and GPUs to utilize all available resources. See the section for more.

V-Ray GPU supports rendering on multiple GPUs. See the sections below on how to choose devices to run V-Ray GPU on.

V-Ray GPU needs compatible GPU device(s) to use for rendering.

Choosing Devices for GPU Rendering

You may not want to use all available GPU devices for rendering, especially if you have multiple GPUs and you want to leave one of them free for working on the user interface, or you may want to combine your CPU and GPU together (see the Hybrid Rendering section below). To do this, click on the Devices button in the Render Settings. It will open the V-Ray Preferences window, with the Device Selection tab opened. From here, you can again toggle between RTX and CUDA modes, and select which of your hardware devices you would like to utilize.

Hybrid Rendering with CPU and the CUDA Engine

V-Ray GPU can perform hybrid rendering with the CUDA engine, utilizing both the CPU and NVIDIA GPUs. V-Ray can now execute the CUDA source on the CPU as though the CPU were another CUDA device. To enable the hybrid rendering mode, select CUDA in the V-Ray GPU Render Settings. You can choose which devices to include in the render from the Devices button.

The hybrid rendering mode does not require any special drivers. Furthermore, you can use the CPU as a CUDA device even if you don't have an NVIDIA GPU and/or NVIDIA drivers installed. This mode can be used on computers that don't even have GPUs. The hybrid render engine running on a CPU supports the same features as the regular V-Ray GPU CUDA engine.

References

• The NVIDIA CUDA developer zone: https://developer.nvidia.com/category/zone/cuda-zone
• For more information on hardware recommendations, see the Hardware Recommendations article.