Issue: Volume 36 Issue 5: (July/August 2013)

Caustic Visualizer for Maya

Gavin Greenwalt

Visualizer is the first in a planned set of plug-ins for Autodesk’s Maya and, in June, 3ds Max. Visualizer for Maya adds to the viewport’s rasterized OpenGL renderer a fully raytraced OpenRL viewport rendering mode as well as a production renderer. This isn’t just an updating view like IPR, but a full-fledged interactive viewport with transform manipulators, lights, shapes, bones, vertexes/edge overlays, and everything else you would expect in a regular viewport but with the added fidelity normally reserved for a finalframe renderers. The easiest way to understand what Visualizer gives you is to take the functionality of Maya’s new Viewport 2.0 but with the image quality of Nvidia’s Mental Ray.

For a real-time raytracer, Visualizer supports an impressive slice of both Maya's and Mental Ray’s built-in shaders and lights. With the exception of a couple notable omissions, such as subsurface scattering and 3D motion blur, Visualizer offers a nearly complete emulation of Mental Ray’s look and feel, right down to Maya’s color management system.

I found a few discrepancies between the Visualizer preview and a Mental Ray render; however, the developers are extremely responsive and seem to be committed to perfectly emulating Mental Ray’s look. I found in my testing that the number of final shader tweaks needing to get a match in Mental Ray for final output were usually minimal. Even with extremely complex multi-layered shaders, Visualizer faithfully reproduced the shader network. I was very skeptical that a third party could accurately emulate all of the idiosyncrasies of Maya’s materials, but Visualizer has proven up to the task, easily besting Maya’s own Viewport 2.0. And with Visualizer’s batch renderer, if you’re happy with the image in your viewport, you’re done, no tweaking necessary!

Visualizer is just like working in any other Maya viewport, but delivers a photorealistic image as you’re working. When it comes to interactivity, Visualizer is in its own class. No other GPU renderer or IPR solution for Maya comes close. While other real-time raytracers, like V-Ray RT, can have up to a second or two of latency after making a change, Visualizer delivers multiple frames per second of feedback. Even while modeling, making topology changes, and tweaking edge loops, Visualizer was able to deliver several frames per second on just the CPU. And if you add in a Caustic R2100 or R2500 RTU, performance is improved even more without being limited by GPU memory. (Caustic coined the term RTU, or Ray Tracing Unit, to distinguish the product from a GPU.)

On an Ace hardware TV spot, I was able to match the lighting and prep the render in a fraction of the time it would have taken through a regular trial-and-error iterative rendering approach or even using a GPU preview. Visualizer changes the way you work. You’re no longer hunting and pecking, trying to guess the perfect lighting setup; you’re simply seeing it play out in front of you in real time and are able to respond to it intuitively as an artist. Visualizer and a Caustic card nearly paid for themselves just in time savings on my first project.

I also like that Visualizer doesn’t lock me into using proprietary lights and materials. If you find yourself in need of some feature that only Mental Ray can deliver, you haven’t wasted any time attempting to optimize your scene for Visualizer: You can simply change your production renderer selection and continue working. It’s very much a WYSIWYG experience, with the choice of outputting exactly what you see in the hardware-accelerated viewport and utilizing the speed of Visualizer, or taking advantage of unique Mental Ray features where needed.

It’s not entirely unicorns and lollipops, though. Visualizer’s v1.0 immaturity is evident in its omission of a few features, which are now a given even for most GPU renderers, such as per-pixel displacement and instancing (instancing is mostly made up for by the R2500’s 16gb of memory, which can hold up to 120 million polygons). Overall, Caustic Visualizer is painfully close to being an extremely disruptive force in the renderfarm space.

Visualizer is a difficult product to review because it doesn’t really fit into any of the normal holes that you would try to judge a renderer by. Its closest comparison would be Viewport 2.0, which ships with Maya. Compared to Viewport 2.0, Visualizer offers unparalleled fidelity and photorealism – and excellent performance. On the other hand, in spite of its currently limited capabilities, it’s impossible to not compare it to a GPU IPR renderer such as V-Ray RT. For look development, compared to V-Ray RT, Visualizer offers better support for complex shaders, sports accurate Mental Ray emulation, and is considerably more interactive and responsive, but it currently lacks some critical production renderer features, such as 3D motion blur and instances. What it lacks in features, Visualizer (especially when paired with a Series 2 RTU) delivers performance and capability in spades.

If you mostly use Mental Ray or Maya lights and materials, Visualizer is an amazing product. If, however, you depend on third-party lights and materials, Visualizer’s value is limited, unless you are willing to accept the aforementioned feature limitations for final frame rendering. With expanded support for other renderers, Visualizer could be a must-have plug-in for every Maya user. As it stands now, though, V-Ray and Pixar RenderMan users should keep an eye on Visualizer’s future updates before jumping into the OpenRL ecosystem.

Gavin Greenwalt is a VFX supervisor and senior artist for Straightface Studios in Seattle. He can be reached at

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