Modeling Quality Control

Vray Rendering Engine

Primatte Keyer

Red Scarlet-X

Keylight Keyer


CheatSheet_Vray01Like most rendering engines, it’s best to make sure all your materials, cameras and lights are specific to the engine you’re rendering with.

In VRay’s case, always use VRay shaders, the VRay Physical Camera, and VRay lights as much as possible, if not totally. They are all built to work in unison, giving you better, faster, and more accurate results. More on this later.

This first page of this VRay Cheat Sheet will focus on the Rendering Global Options. The second page will discuss VRay Materials, and the third will discuss Lights and Cameras.

Essential Options:

CheatSheet_Vray021) File Name Prefix: write out the filename sequence you want to save your renders to. Never use a lossy compression unless it’s for preview purposes only. I usually stick with TIF, TGA, or OpenEXR (best). For more information on filetypes, check out my Filetypes CheatSheet.

2) Image Format Options: I always use lossless compression. For the TGA format, I use RLE (Run Line Encoding), for OpenEXR, I like PIZ or ZIP. Kick your bits per channel up from 16 to 32 if you will do color correction or are rendering out HDRs (High Dynamic Range Images).

3) Animation Checkbox: Check to render out a sequence of frames by specifying Start and End frames. VRay does not render out self-contained, compressed movies like AVI or MOVs, for various reasons. You can compile your frames in another program if you need a rendered, preview movie like After Effects or Premiere.

4) Renderable Camera: Pulldown to select your camera view to render from. You may still need to re-activate the proper window (simple click in it) if you change your view during renders.

5) Resolution: Choose a preset or custom pixel size. HDTV 1080 is 1920×1080, 720 is 1280×720. Anything smaller should be for preview or web.

CheatSheet_Vray036) Use V-Ray VFB: Using the VRay Frame Buffer will give you interactive bucket control so you don’t have to wait for the computer to get to the part of the image you are looking for (just hold the mouse over the area to render next). Similar to an on-the-fly ROI (Region-of-Interest).

7) Hide Render View: This will hide the Maya default render buffer window. As of the latest version, there is a bug in which VRay ignores this selection and always displays it.

8) Render Viewport Subdivision: This allows you render your geometry in subdivision preview mode (Maya: 3 on your keyboard) without Smoothing modifiers on your meshes and baking in heavy topology. Keep in mind, VRay Proxies ignore this setting and you must mesh smooth to render smoothly.

CheatSheet_Vray049) Turn off Default Lights: Only use the lights you added to the scene, not the viewport lights. If both options are off, you get a black scene. Don’t turn this off if you haven’t added lights.

10) Sampler Type: The core of VRay – simply, this is how well the image will look. Choose Adaptive DMC (Deterministic Monte Carlo). There are three flavors of Sampling in VRay- Fixed, DMC and Subdivision (version 3 of V-Ray now comes with a fourth sampler type: Progressive – more on this later!). You want to choose the one most appropriate for your scene. I use Adaptive DMC most of the time. More on this in Advanced Settings.

11) Adaptive DMC Max Subdivs: How many times the pixel will be subsampled. The actual number of pixel samples is the square of this parameter (e.g. 4 subdivs produce 16 samples per pixel). Use between 4 to 10 for quick renders, 50 to 100 for production renders. More on this in Advanced Settings.

12) Threshold: This is the noise in the render (in actuality, it is the color threshold that is measuring the difference in intensity between neighboring pixels). 0.1 for quick renders, .01 to .005 for production renders. More on this in Advanced Settings.

13) Motion Blur: Turn on for motion blur for production renders. Keep off for drafts and previews as this will slow down render times.

Indirect Illumination Tab

CheatSheet_Vray0614) On: This is your bounce light. Keep off for faster renders in draft mode, though GI calculation is normally very fast anyway.

15) Primary Bounces: First bounce calculation. Choose Brute Force. More on Primary Bounce Engine types in Advanced Settings.

16) Secondary bounces:All bounces after the first bounce. I use Light Cache here. More on Secondary Bounce Engine types in Advanced Settings.

17) Light Cache Passes: the number of threads you are rendering on. I have a 6 core, hyper-threaded machine, so I choose 12. If you specify less threads than your computer has, you will get a warning that some threads are idle and lose performance.

Settings Tab

18) Dynamic Memory Limit: This will help you avoid from crashing your program if the scene is too heavy when the ray caster is using Dynamic or Auto. Here’s the simple formula: (RAM – OS = DML). I use 30,800. Ram (32 gigs – Windows 7 overhead = 30800)

CheatSheet_Vray0719) Use Distributed Rendering: This allows you to steal processors from other computers on your networks long as they are running VRay Render Slave. Make sure all your textures are either with relative paths or are copied to the same place on all network computers (otherwise network buckets will come back black).

That’s it! That’s all you need for a quick render without much tweaking. Now let’s get into the nuts and bolts!

Rendering out 16-bit TIFs from VRay Maya and importing into Nuke will give you a channel-read error on the Read nodes. Instead of re-rendering, resave them through a batch action in Photoshop.

If you don’t set up your Project Settings and folders per maya file, just include the full path for the renders in the File Name Prefix.

You will get physically accurate lighting if you set both the primary and secondary GI multipliers to their default value of 1.0. While other values are possible, they will not produce a physically accurate result.