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Tuesday, July 9, 2013

How to make volumetric lights and fog in V-ray for Maya (God rays)

This is not that hard to accomplish but no one ever writes tutorials on it! How frustrating... here is how to do it.

NOTE: The fog effect will be affected by the scale of your scene so probably best to work in real world scale. This tutorial was done at a relatively small scale so you may need to adjust your numbers some from my values.

First set up the scene for you shafts of light. In this case we are going to make a window with sunlight flowing in the window.

I've created a simple hollow box with a cut out in the wall for the window.

Create an area light top create menu>lights>v-ray rect light. and position it in your window to give you some soft ambient light filtering int other room.

Now in your V-ray render settings. Indirect illumination tab let's turn on GI.

Now create a normal spot light creat menu>lights>spot light.

Position your spot light so that it some distance away from your window and focused in on it. Narrow the angle on the light so that it's literally spotted right on the window.If it helps you can select the light in the outliner and then in your viewport Panels>Look through select to aim it
right in line wit the opening. Make sure to turn on "Use Raytrace Shadows" in your spot lights settings.

You should have something like this we can see the spot light gently hitting the floor.

Now let's turn on volumetrics. Goto your V-ray render settings. v-ray Tab. Then to the Environment sub drop down. Turn on "Use environment volume" checkbox. An press the checkerboard box to load it.

The create render node screen comes up. Type "fog" in the quick search box at the top option to select Vray Environment.

Now press the arrow next to the Environment Shader to see the settings for your fog effect. Let's do a test render.

At the default settings the scene may be very dark or even render black. This is because of how thick the fog is.

Now you could turn the fog density down, but then you will lose your "shafts effect" so let's instead turn the lights up.

First turn your area light at the window up to 3.

Now let's turn our spot light up to 300.

And now we finally have shafts beginning to show up. Everything is pixeled though so go back to your fog settings.

Render settings>V-ray Tab>environmental drop down. Press the right arrow. And turn up the Subdive setting on your fog to 32. Then turn the Shadows rays up on your area light and spotlight to 24. To smooth things out.

This should give you a good starting place for creating volumetric light effects on your own. Here is a great

To get even more realism in your Fog you can play with the Scatter GI properties in your fog attributes. Set it from 50-200 to see the effect of the GI bouncing around in the Fog.

The final render is looking much better. Now go make some sweet volumetric scenes with V-ray for maya!!
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