Getting Started with Arnold GPU

Supported Features

Arnold core features

Arnold GPU supports a set number of Arnold features, including arbitrary shading networks, SSS, hair, atmospherics, instancing, and procedurals. See here for a detailed list of Arnold GPU features and known limitations.

C4DtoA features and known limitations

• Turbulence FD and X-Particles volumes are not supported
• C4DtoA specific shaders from previous versions (prior 2.5.0) are not supported (e.g. when loaded from a previously exported ASS file via an Arnold Procedural):

• • normal_displacement
  • vector_displacement
  • mesh_light_material (visible mesh light)
  • c4d_vertex_map (Vertex Map)
  • xparticles

System Requirements

Pre-populating the GPU cache 

The very first time you render with the GPU, the GPU renderer has to create a cache of shaders. This can delay the time to the first pixel for your first render.

To avoid the one-time delay, we recommend that you run Pre-Populate GPU Cache before you do any renders. Note that pre-populating the cache can take up to 15 minutes.

The cache only needs to be re-populated after installing a new Arnold version, updating to a new NVIDIA driver, or changing the hardware configuration of GPUs on the system.

Selecting a Render device

You can easily switch between CPU and GPU with a single click in the System render settings. 

Matching Noise on CPU and GPU

Matching noise can take a little experimentation because Arnold GPU uses Camera (AA) sampling only. We recommend you also use Adaptive sampling. Here are some guidelines:

• Set the Max. Camera (AA) in the range of 30 to 50 (depending on the scene, you might go closer to 100). In general, the max samples should be a large value. A large max samples means that the quality is controlled by the noise falling under the threshold, instead of by clamping to the max AA.
• Set the Adaptive Threshold to something like 0.015 or 0.02. For a noise-free render, lower the threshold value, maybe even as far as 0.010.
• Set the Camera (AA) samples to around 3 or 4. One of the few reasons to go higher with AA is for motion blur. The higher the number of Camera (AA) samples, the less of a speedup you'll get from adaptive sampling.