Category Archives: Uncategorized

mental ray Progressive Rendering and AO Acceleration

Facilities that have had raylib integrations of mental ray have long had access to developer examples of progressive rendering and new features as they are released. Unfortunately this hasn’t been the case with OEM integrations and most users have had to wait for these updates. In addition to that, Maya doesn’t have all the necessary pieces to make true interactive rendering easy to expose.

The Official mental ray Blog “Inside mental ray” has just posted an example of Ambient Occlusion (AO) rendered progressively using GPU acceleration in mental ray. This is a great example of ongoing improvements and scene examples using the correct API for features like progressive rendering.

This is also a good way to see further development in GPU acceleration and where it would be useful for scene rendering and look development.

The video is embedded below but be sure and visit the mental ray Blog to see a great explanation by Rajko.

mental ray – In The Lab

Xgen Hair in mental ray

Part of building a better user experience for mental ray in Maya is providing information on how to use features in Autodesk Maya 2015 like Xgen hair.

Sandra and Julia at NVIDIA ARC have written a quick tutorial on using Xgen hair with custom shaders and expressions to control hair rendering in mental ray.

Take a look at their post here. There’s also a comments section if you have a question on the tutorial.

Happy rendering!

Expressions in Xgen

mental ray Direct Sales and Support

Just announced is that NVIDIA is now selling mental ray Standalone directly to users. Previously you would buy Standalone from your integration partner like Autodesk as well as support. This support comes with as few as 10 licenses.

Important things to note about this:

  • Support is provided through NVIDIA directly
  • Access to private support forum
  • Enables DCC application updates
  • Types of support based on customer and need
  • Current versions of mental ray available as well as fixes sooner

As a side effect this moves mental ray into the realm of a separate product from DCC applications and makes NVIDIA the source of information for mental ray in the future. Feedback from customers now reaches developers at ARC without filtering through an integration partner.

Take a look at their new page here: mental ray Standalone

Official Blog announcement here.

Courtesy Jamir Blanco

GI GPU Prototype Testing

You can find more details and some newer test images on the Official mental ray Blog. Take a look here.

Also a new post with illustrative animation on exposed settings can be found on this blog here.

GI rendered with the GPU, image courtesy of Lee Anderson.

See Lee Anderson’s original version of the above image at his site here:

Maya 2015 shipped with an additional but unexposed feature to use GI on the GPU. You can learn more about this feature here. You can also hear more about where this is headed here.

**NOTE: this is a PROTOTYPE of a feature as-yet uncompleted (alpha stage). Testing is being made possible by cooperation with Autodesk and NVIDIA ARC. Your thoughts on controls and most important features to support are very important to collect.**

The prototype is a limited-feature version initially released for simple scenes and testing. It does not support everything you’re used to yet like motion blur or visibility cutouts. However, it operates as a brute force solution on the GPU or CPU, allowing you the flexibility to render it on the necessary hardware or take advantage of the speed offered by GPUs. Note that you should be using an NVIDIA GPU that is a newer generation to take advantage of the feature (able to run Optix Prime) This GI feature is very fast on the GPU and is under active development at NVIDIA ARC. A thread has been started in the 3ds Max and Maya ARC forums along with a simple UI to allow you easier usage of the feature. You can learn how to use the feature from developers and what to expect when it is complete. Find the Maya thread here. Main controls to note:

  • Rays: Primary quality control
  • Anti-Aliasing Passes: The number of passes per pixel (GPU implementation) Note that this multiplies the rays for each pixel based on its value. If you increase it, think about lowering the ray count. A minimum value of 4 is recommended as well as keeping the integer a square of some number, i.e. 4, 9, 16, 25, etc
  • Filter: This does not operate in the same way as the FG interpolation filter and typically provides better results. It is measured in pixels. Higher numbers can destroy shadow details. I recommend trying to keep it low. (5 or less) 0 is off. Hopefully more will be explained about this technique at SIGGRAPH….
  • Mode: Diffuse only is the most complete feature. This ignores specular interaction but is typically enough for VFX-type scenes. It’s also the fastest mode. Other modes may not be finished and/or rely on older techniques initially.

In order to use the GPU effectively, your scene must be able to fit all geometry onto the GPU memory. Hair is tessellated right now. Presampling provides the data for shaders so texture data isn’t loaded at the same time. This allows you to use legacy and/or custom shaders without penalty with the new technique. Since motion blur isn’t currently supported I wouldn’t use this for animation unless you use post blur. If your scene is particularly dense, you can use the CPU mode with another option.   Improved GI (using GPU) Improved GI (using GPU)