Product design visualization needs the highest visual quality possible – as fast as possible
How does VRED 2021 provide users with real time raytracing? Autodesk implemented a rendering pipeline that combines NVIDIA’s hardware accelerated raytracing and hardware accelerated AI-based de-noising functions. How can you take advantage of this new feature? Let’s take a look.
How to setup real time ray tracing in VRED
The first step is to enable raytracing. Go to the Raytracing icon in the menu strip and opt for either CPU or GPU raytracing. (see images below)
With one of the options enabled, go to the Rendering pulldown menu and select Render Settings. A multi-tab dialogue box opens.
In the General Settings tab, you can enable and disable the de-noising option. Then select the Raytracing options in the same dialogue.
Here, you set the illumination mode and this determines the image’s raytracing rendering quality. The five options start at Precomputed and end at Full Global Illumination.
Set the raytracing quality settings by selecting one of these five options.
This video shows CPU and GPU raytracing performance with several rendering modes.
What is under the hood? A look at the Quadro RTX 8000 architecture
The Quadro RTX 8000 is the most powerful Quadro in the RTX family and is based on NVIDIA’s Turing architecture. The GPU has over 18 billion transistors and it has 48 GB of GDDR6 ECC graphics memory.
What is interesting here are two specialized groups of cores in the GPU. The first are the 72 RT Cores which support the GPU for raytracing. The second are the 576 Tensor Cores. In this case, the Tensor Cores accelerate the AI-based de-noising feature in VRED. GPU de-noising is used whether the raytracing is done with the GPU or with the CPU.
This makes it possible is to quickly generate an initial but incomplete raytraced image with the raytracing hardware. That image is sufficient for an AI to apply de-noising and finish the image much faster than it is possible to do using brute-force computations - even with dedicated hardware.
Select the Raytracing option to turn on GPU or CPU raytracing.
In the Render pulldown, select the Render Settings option.
In the General Settings tab, turn on and off the (GPU) de-noising function
Set the interactive quality level for raytracing in Raytracing Quality tab
How fast is real time ray tracing and how is the quality?
If raytracing is not used, then VRED renders this model at well over 200 FPS. That is more than enough for applications like virtual reality.
| Render Setting | GPU | CPU |
|---|---|---|
| Precomputed | > 42 FPS | 6-7 FPS |
| Precomputed + Reflections | > 25 FPS | 4-5 FPS |
| Precomputed + Shadows | >15 FPS | 3 FPS |
| Precomputed + IBL | 9 FPS | 2.5 FPS |
| Full Global Illumination | 8 FPS | 1.5 FPS |
| Full Global Illumination + De-noising | 7 FPS | 1.2 FPS |
VRED's de-noising uses the GPU for both GPU and CPU raytracing.
In these performance tests, the model, the lighting, and the other objects in the scene are static. I only change the viewpoint. In this situation, using one of the precomputed render settings could be sufficient. In this case, VRED and the Quadro RTX 8000 render more than 40 FPS.
But as soon as lights and objects in the scene are moving, selecting a more intensive raytracing setting is useful. For this scene, VRED and the Quadro RTX 8000 render a respectable 7 FPS with full global illumination and de-noising enabled. And while the scene is static in this example, I would expect the same performance in a dynamic scene since lighting, reflections, shadows, etcetera, are calculated for each frame.
In the case of CPU rendering, the frame rates begin for the dual Xeon below the performance where the frame rates for the Quadro RTX 8000 end. And I should stress that in the final test with de-noising, the de-noising function is still performed by the GPU, not the CPU.
The short video shows GPU and CPU rendering side by side for each of the raytracing rendering settings. There are other setting combinations possible. For example, any of the settings with calculated shadows could also add the de-noising step which I only do in the final setting of full global illumination. None-the-less, the video should give you a good feeling for the level of rendering quality and performance in VRED.
Autodesk VRED’s render quality settings:
CPU Rasterization - Does not compute direct reflection, refraction, or any other sophisticated visual effect. (editor’s note : this is not a raytracing mode)
Precomputed Illumination - Comparable to VRED OpenGL rendering mode, this uses precomputed ambient occlusion and indirect illumination for rendering and calculates specular reflections and refractions and correct shadows from light sources.
Precomputed + Shadows - Uses precomputed image-based lighting and indirect illumination, but does not use precomputed ambient occlusion values. Instead, it calculates shadows based on the active environment.
Precomputed + IBL - Uses precomputed indirect illumination and samples the environment.
Full Global Illumination - Does not use any precomputed values, however, it accurately samples the global lighting distribution in a physically-based approach. Some features like Photon Mapping require the render mode to be set to Full Global Illumination.
A Final Perspective
In product design, image quality is everything. In a competitive world, speed is everything. VRED 2021 and an NVIDIA Quadro RTX 8000 workstation give you the best of both.
VRED achieves this by combining NVIDIA’s hardware accelerated raytracing pipeline and NVIDIA’s AI pipeline. The hardware acceleration in both areas is new with NVIDIA’s RTX family of GPUs.
The great news for product designers is that the trade-off between interactive visualization and raytraced rendering quality is disappearing. Now that it is in Autodesk’s VRED, the functionality can only get better as NVIDIA improves performance and Autodesk continues to optimize VRED.
