V-Ray for Maya – Tips and Tricks

As a new user to both V-Ray and Maya, I was incredibly frustrated by the lack of tutorials, documentation and general user guides. Learning by trial and error is rewarding but also very slow and not ideal in a production environment.

These things improve over time and this page is my attempt to contribute.  The aim is to collect bits and pieces of useful information that people might need in everyday work and add to the list over time. I might even start adding images.

Some parts may become outdated as new releases roll out but sometimes even old information is better than none at all.

FumeFX smoke flickering when using V-Ray Dome Light

V-Ray 3.0 – FumeFX 3.5.5 – Maya 2015 Extension 1 +SP5

Nasty flickering going on in your FumeFX smoke? This is a combination of V-Ray’s Importance Sampling and Fume’s Illumination Mapping. You could turn off the Illumination Map but that would just kill your render times, so it’s easier to go the dome light’s settings and turn off Tex Adaptive.

Fixing faceted displacements (or pixelated textures in general)

V-Ray 2.4 – Maya 2012

Doing displacements and seeing ugly faces of polygons on the surface? That’s just your texture that needs a proper filter applied to it. Go to your texture file node and add V-Ray Texture Filter from the Attributes. Check the activation checkbox and set the filter to Smooth, or Smooth with mipmaps. The method you can leave to whatever you think looks best. Fixed!

Quick Linear Workflow

V-Ray 2.4 – Maya 2012

For new users, trying to wrap your head around the whole Linear Workflow thing can be enough to make you run into the forest, live in a cave and never look at a computer again. The thing is, most people make it sound far more complex than it should be from the point of view of a CG artist. To simplify: A gamma of 0.4545 gets applied to all incoming color values and a gamma of 2.2 is applied to the resulting render. I’ll probably be ripped to pieces by people who are far more techs savvy than me for saying that.

There’s two ways of working with Linear Workflow in V-Ray for Maya: Manual and accurate when you know what you are doing, or automatic and good enough for lazy bastards (like me). How to make use of the latter? Just use the settings in the image above and you are set.

Couple of things to keep in mind though. Always render out in a 16- or 32bit format when using LWF. In other words, save your images as EXR. Oh, and remember to tick the Convert image to sRGB for RenderView under VRay Common tab or your renders will look way too dark.

That’s a quick fix. I recommend delving deeper into the matter since LWF affects your output quality in a major way. Just be prepared to be confused.

Motion Blur with RealFlow

V-Ray 2.4 – Maya 2012

Figuring out what settings to use to get V-Ray’s motion blur to work with meshed RealFlow bin-files required some research and I finally found these buried somewhere in the official V-Ray forums. The relevant fields can be found under the Camera panel in the V-Ray tab of render settings.

Duration set to below 1. (Default 1.000)
Interval Center to 0. (Default 0.500)
Bias to 0 (Default is 0.000 anyway)

Enjoy the beautiful motion blur! Keep in mind that you might have to tweak the Geometry Samples option if your fluid mesh is moving really fast and you start seeing some odd ghosting effects.

Matching Camera and Motion Blur in V-Ray and Nuke

V-Ray 2.4 – Maya 2012 – Nuke 7.0v9

There’s a couple of things you need to consider when matching renders in V-Ray and Nuke’s scanline. First is the Fit Resoluton Gate in your render camera Attributes. If your Film Back doesn’t match your resolution, this should be set to Horizontal. This is also the setting to use whenever you are exporting the camera to be used in just about other 3d application.

The second important thing is to tweak the Motion Blur. Set the Interval Center to zero and you are good to go.

In Nuke, go to your scanline render option and find the MultiSample tab. Put the Shutter Offset setting to Custom and 1, then tweak the Shutter settings until the scanline output matches whatever is coming out of V-Ray.

Getting rid of noise in specific areas

V-Ray 2.4 – Maya 2012

One of the things I fell in love with when I started using V-Ray was that you can really easily direct your samples where you need them. When dealing with noisy images, increasing general sampling can often lead to frustratingly long rendertimes and you really want your CPU to spend it’s time where it counts. Always try increasing specific subdiv settings before touching the overall sampling parameters.

The trick is figuring out what exactly is the cause of the noise. Noisy shadows? Increase the subdivs in your area light settings. Motion blur not smooth enough? Check the settings under Camera panel in Render Settings. You’ll find subdiv parameters just about everywhere in V-Ray, be sure to make good use of them.

Using Multi Mattes for easy object and material masks

V-Ray 2.4 – Maya 2012

Multi Matte is an easy way of producing multiple matte passes without relying on cumbersome render layers. This works both on materials and objects, so it’s super-useful.

First, create a Multi Matte render pass under Render Elements tab in Render Settings. Just find it on the list on the left, double click on it and it’s active. You can now access the settings, which you might want to tweak a bit. It’s a good idea to turn on Consider for Anti-Aliasing as well as Use material IDs. Make sure you assign different IDs to different colors, 0 for Red, 1 for Green, 2 for Blue for example.

Keeping in mind what ID numbers we assigned, you can now add the attributes to any object or material you wish to use as a matte. Just add an Extra Vray Attribute from the dropdown, assign an ID and you’re set. Easy!

PS: Mask not visible through a transparent material? Make sure you have Affect Channels set to All Channels under Refraction in the V-Ray material settings. Thanks to Juuso for the tip.