How to Use Environment Fog in Solaris

V-Ray provides tools for creating an atmospheric effect simulating particulate media, such as fog, atmospheric dust, and so forth. The tools can be used both in Houdini and Solaris. In this tutorial, you will learn the workflow in Solaris. The scene used is very simple in order to quickly and easily teach you the basics.

Download Sample Scene

• Add a SOP Create node and, within it, create a geometry to serve as a container for the fog. Adjust the container's size and position if needed.

For this tutorial, a simple box is used as the container.

• Next, create a Material Library LOP, and dive inside it. There, create a V-Ray Material Builder to act as the fog's material. This can be done by right-clicking and selecting V-Ray > Material > V-Ray Material Builder.

Name the material accordingly, e.g., Fog material. In scenarios involving more complex scenes with multiple materials, proper naming will significantly facilitate navigation and management.

• Inside the V-Ray Material Builder node, both a V-Ray Material and V-Ray Output nodes are automatically created.

The V-Ray Output node helps you control which materials inside the builder are to be rendered at the end.

• Create a V-Ray Single material by right-clicking and selecting V-Ray > Material > V-Ray Single. Place it between the V-Ray Material and the V-Ray Output, ensuring that the BRDF input of the V-Ray Single material is connected to the output slot of the V-Ray Material, and its output slot is connected to the material slot of the V-Ray Output.

The V-Ray Single material is needed to treat the fog as an environment fog in Solaris/USD. Its Env. Fog. Mode (USD) option must be set to Environment Fog.

• Reduce the opacity of the V-Ray Material to 0; this parameter can be found in the material’s Diffuse tab.
• Add a V-Ray Fog Effect node by selecting V-Ray > Effects > V-Ray Fog Effect. Connect the node to the use_env_fog input of the V-Ray Single material.

You can add textures for a more complex fog effect look, e.g., V-Ray Checker or V-Ray Noise, or keep it simple.

• Exit the Material Library LOP and create an Assign Material LOP.
• Assign the fog material to the box geometry. To do this, drag the sopcreate1 into the Primitives field of the Assign Material parameters, and drag the Fog material to the Material Path field of the Assign Material parameters.

Alternatively, use the Select primitives button on the right of each field or directly type the paths.

More information on material assignments is available on the Working with Solaris Materials page.

• Return back to the Fog Effect parameters inside the Material Library LOP. There, you might need to adjust the Distance a bit. Configure the rest of the parameters to your liking.

You can find information on each parameter and its effect on the fog on the V-Ray Fog Effect page.

In this tutorial, the following V-Ray Fog Effect parameters are tweaked: Color is green, Phase Function is -0.185, Distance is 0.5, and Density is 0.45.

• Select V-Ray as the renderer in Solaris. See an example rendered image on the right.