3D Animation

Rendering with mental ray

October 30, 2008 October 30, 2008 So who likes rendering? Who likes rendering with mental ray®? Everyone’s hands went down, I know it. Okay, admittedly mental ray is not the easiest, friendliest renderer out there, but once you get to know it, it is one of the most robust, tweakable, powerful renderers (as well as one of the most prevalent) in the industry. And hey! It comes free with every copy of Maya, so it’ll also save you a few thousand bucks toward buying another third party renderer. mental ray is at heart a physical renderer - meaning it attempts to recreate the physical properties of light as you and I see them, instead of using tricks and "cheats" to achieve the same effect (not that cheating is inherently a bad thing; sometimes it’s necessary to get a project done on time). The problem is, actually recreating the physical world takes quite a few complex algorithms to achieve. This is where we get things like Global Illumination, Caustics and Final Gathering. The complaint most people have is that they are too tricky to set up in Maya, and if not tweaked properly, can take forever to render. Well, thankfully there are a number of settings you can alter to make sure a render doesn’t take forever. Here’s a hidden node that can be used to get "under the hood" of mental ray: Type these 2 lines of code into the command line (or save them to a shelf): select metalrayGlobals;openAEWindow; This opens the hidden settings of mental ray, where you can really fine tune the render. Start with the Memory and Performance dropdown. Here you can set the amount of physical memory that mental ray can use (don’t set this to the maximum your computer has; you need to leave some for the OS). You can also change the Acceleration Method to BSP2. This is an advanced and new mental ray algorithm that automates a lot of the render time breakup of your scene, so things like Final Gather and Global Illumination tend to render quicker. You can also uncheck "Inherit Verbosity" near the top, and change the Render Verbosity to "Progress Messages", which will give you a detailed readout of what exactly is happening as mental ray renders in the Output Window (the other window that opens when Maya starts). Reading and understanding these messages can help you to further refine the settings to speed things up. A final note, some resources to fully understand what’s actually going on: the book "mental ray for Maya, 3ds Max, and XSI: A 3D Artist’s Guide to Rendering" by Boaz Livny and the site www.mentalraytips.com (some fantastic advanced tips can be found there). Check ‘em both out, then get cracking on those renders.