GPU Ray Tracing Inventor 2023

Autodesk Support

Feb 3, 2022


Overview

Inventor 2023 introduces a new display option that takes advantage of support for hardware ray tracing in recent graphics cards (GPUs). This feature is called GPU Ray Tracing. It is in a pre-release state in Inventor 2023 and will be improved in future updates. Current limitations are described later in these notes.

In earlier releases of Inventor, selecting the "Ray Tracing" display option in a viewport would use the Autodesk Raytracer (ART) which provides interactive results using only the CPU. Now you have the choice to use GPU Ray Tracing in its place, with the potential for higher performance and quality using your GPU.

Using GPU Ray Tracing

To enable GPU Ray Tracing, your system must have a compatible GPU, and then the option can be enabled with Tools > Application Options > Hardware > Enable Viewport GPU Ray Tracing, as shown here:

Once the option is enabled, you can turn on the Ray Tracing display option in a viewport, from the toolbar as before. Note that the "Realistic" visual style must be selected for Ray Tracing to be available.

When GPU Ray Tracing is enabled in a viewport, a small window will be displayed at the bottom right of the viewport:

This includes the following options:

  • Noise Reduction: This applies a "denoising" filter to the result, which allows for the immediate reduction of noise artifacts, which is much faster to render. Denoising can result in some loss of detail in materials or lighting, but often provides a good and rapid result.
  • Quality (Low / Draft / High): This controls the target quality level of the rendered result. Higher quality will take longer to complete but will have fewer artifacts.
  • Save: Save the current rendered image to disk, using the dimensions of the viewport.
  • Pause / Continue: Temporarily stop rendering the current image or resume it. If rendering is already completed (progress at 100%), Continue will collect more samples to further refine the image. This is useful if noise artifacts are still visible.
  • Disable: Finish GPU Ray Tracing and return to the normal Realistic display mode.

GPU Requirements

The performance of GPU Ray Tracing depends heavily on the GPU, with newer or more capable GPUs potentially performing several times faster than older or less capable GPUs. PassMark Software publishes GPU benchmark results that may help you compare options. The "GPU Compute" results correlate closely with GPU Ray Tracing performance.

Image Quality

The topic of image quality is important for GPU Ray Tracing, and two aspects of it are worth describing further: rendering progress and materials (appearances). Image quality is an active area of development for GPU Ray Tracing, and we welcome any feedback you may have on the rendering experience. See the "Providing Feedback" section below.

Rendering Progress

When rendering begins, you will see obvious "noise" artifacts that will resolve over time, as more path tracing sampling are collected. GPU Ray Tracing shows a progress bar that reflects how many samples are collected, relative to the target quality level. With path tracing, rendering is technically never complete, and you could continue rendering indefinitely.

However, in practice, artifacts are quickly resolved, and you will often see good results even before the target quality level is reached. You only need to wait until the image looks good enough for you. The "Continue" option lets the renderer collect more samples if you still see objectionable artifacts.

With the Noise Reduction option enabled, you will usually see few noise artifacts, and achieve good results even faster. However, noise reduction can result in some loss of detail in materials or lighting. If you are interested in saving a "final" rendered image for sharing later, you may want to disable noise reduction and allow the renderer to spend more time rendering.

Materials (Appearances)

GPU Ray Tracing also uses physically-based rendering principles. This means that lighting and materials interact in a way that mimics reality, and more realistic results can be achieved with minimal effort from the Inventor customer. This differs somewhat from earlier renderers but is now becoming common in computer graphics.

In particular, GPU Ray Tracing uses a new physically-based material definition called Autodesk Standard Surface. This definition can represent a wide range of materials often used by Inventor customers. No extra work is required by you. GPU Ray Tracing will automatically and quickly convert your existing Inventor appearances to Standard Surface for rendering, there is no change in the appearance editing user interface.

However, this conversion process may result in visual differences between what you saw with ART and what you see with GPU Ray Tracing. Some of these are known limitations and may be addressed in the future, but in some cases, you may see differences that come from having previously used non-physical material properties. For example, physically-based materials conserve energy, so you may notice that materials that were previously too bright are now darker.

Rendering Timeout

In some situations, GPU Ray Tracing may stop due to taking too much time to render. This happens because Windows includes a feature called Timeout Detection and Recovery (TDR), which will reset a GPU when an operation takes longer than two seconds (by default). In GPU Ray Tracing, such a single operation may be rendering a single sample, which should normally be fast, and certainly less than two seconds.

A timeout occurring when rendering a single sample usually means one or more of the following:

  • The GPU has low performance for hardware ray tracing.
  • The model being rendered has complex geometry, materials, or lighting.
  • The model occupies a large part of the viewport (window), i.e. zoomed in.
  • The viewport size is large, such as with a 4K monitor.

When a timeout happens, Inventor will automatically disable ray tracing, and revert to the normal Realistic display mode. The following message will appear, with the choice to revert to using ART instead:

Providing Feedback

If you want to provide feedback on GPU Ray Tracing or other features in Inventor 2023, please consider joining the Autodesk Forums at forums.autodesk.com. There you will find a forum for Inventor, where you can ask questions that will be visible to other customers and the Inventor team.

Thank you for your help!

Known issues and Limitations

Supported Graphics Cards



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