This tutorial shows you how to create the God Rays effect in V-Ray for Houdini.
Overview
"God rays" is a volumetric effect, often used by 3D artists to add a more dramatic effect to a 3D scene. The effect is achieved when a directional light (such as V-Ray Sun) passes through a dusty or foggy atmosphere.
In this tutorial, you can explore the easiest steps on how to get the effect.
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Workflow
Make sure there is a directional light such as the V-Ray Sun in the scene. Other types of lights also work, e.g. a V-Ray Rectangle Light when the Directional parameter is increased.
Create Fog Effect
Create a V-Ray Fog node. To do so, go to the |out| network and add a V-Ray Environment node. Inside this node, create the V-Ray Fog node from V-Ray > Effects > V-Ray Fog Effect.
The fog now renders in the scene, but the default settings do not suit the scene's measurements well. Let's explore the Fog Distance and Fog Height options.
Fog Distance
The Distance parameter controls the distance of the fog from the camera, essentially controlling the fog density. Larger values make it more transparent, whereas smaller values make it denser.
For this particular scene, a value of 10 makes the fog extremely thick, so increase the Distance to something like 850.
Distance is 10
Distance is 300
Distance is 850
Fog Height
The Height parameter determines the height of the fog. For this scene set it to something like 330 so it covers all the wooden interior.
Height is 10
Height is 330
Height is 500
Fog Color
The Color parameter determines the color of the fog - see how changing it affects the overall mood. For this particular scene, let’s settle with dark blue to achieve an eerie look.
Color is light green
Color is dark green
Color is blue
Modify Lights
To further enhance the effect of fog color, tweak the V-Ray Sun light parameters. Change the Sun color to bluish.
When multiple lights are present in the scene but you want only some of them to be responsible for the god rays effect, you can include light sources by setting the Light Mode to Selected Lights in the fog node and then adding the lights to the Lights list.
Final Result
Now let's add some more geometry to the scene and apply materials to them to complete the look of a boat's interior.
