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VRayEnvironmentFog as Volume Light

Here’s another PRO method for adding realism to your images. VRayEnvironmentFog can be used to create realistic looking volume light. You can add it to your VRaySun or other VRay Lights, such as VRay IES. Remember this is going to take some extra time so make sure to take your lights aside and test then in an empty scene where you have just several boxes and opening.
After you adjust and find that your light beams being created perfectly to match you scene, merge your main objects that and being hit by the sun and render that image without introducing GI.
That way you will have a clean pass to play with in post work.

To demonstrate how to use this effect, I’ve created a simple interior setup. I’ve added a lot of openings to the side of the wall where our VRaySun will shine through.

Just to shorten the calculation time for this effect, we’ll restrict the fog to a box. We’ll start by adding a Box Gizmo from the Atmospheric Apparatus helpers control panel. Give it the dimensions of our interior space. We’ll be able to use this box as a container for the fog.

Adding VRay Environment Fog

Now we’re going to add our VRayEnvironmentFog effect to the scene. Go to the Environment and Effects menu by pressing 8 and add the VRayEnvironmentFog in the Atmosphere Effects rollout. This effect has some simple controls for tuning your fog. You can set the strength of the fog by using the fog distance and fog height parameters. The longer the fog distance, the weaker the fog effect will get. In the same way, the higher the fog height, the denser the fog becomes.

I’ve set the fog distance to 10m for this interior space and kept the fog height at 1m. The subdivs parameter will control the quality of your noise effect. I’ve also kept the ‘scatter gi’ option unticked as this will increase our render times by a lot. Also worth mentioning is that we can render this effect without GI in our scene and use it as a pass in Photoshop. This is a quick way of adding subtle volume fog without wasting precious render times.

Now add the BoxGizmo to the Gizmos node in VRayEnvironmentFog, and the VRaySun to the Lights node. The effect will now be restricted to the interior space and calculated just for the VRaySun light. Disable the Global Illumination and Affect GI and do a fast test render. If you’re happy with the effect, you can enable GI and render the final result.

Next up I’ve also added some VRay IES lights to the scene and the light nodes list. I’ll just render this one without any GI calculations and use it as a render pass. Moving over to Photoshop, I’ve added this render pass over the original render with the Screen blending mode. Playing around with the Opacity controls gives me the exact amount of light beams I want in the scene.

Hope you’ve enjoyed this PRO method for adding realistic light beams with VRayEnvironmentFog.
Share it with your friends on FB twitter and Google+

POST YOUR COMMENTS BELOW!
Talk soon,
Alex

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