Creating fog with Thea for Rhino
The optimal way to use Global Medium is by using a box surrounding the scene and limiting this way the calculation to that specific area.
Step 1: Creating the Container
Create a box containing the part of the scene that you would like to render.
Step 2: Fog Material
- In order to have fog in the scene, we need to create a new material and apply it to the container object that we created in the previous step.
- Delete all the layers from the material, switch to the Medium tab and enable it by clicking on the checkbox.
- Set a near-white color (e.g. 240,240,240) for both Absorption and Scattering Color.
- Change the Absorption and Scattering Density values to 0.001 and 0.01 respectively.
Step 3: Assign the Medium material to the Camera
The only problem now is that once the camera goes inside the Container object that created in the first step, we will not be able to see the fog. For this to work, we need to go to the Camera Tab and from the bottom of the panel, in the Asssign Container section, switch from Global Medium to the material we created in the previous step.
Controlling the density
In order to control the density of the fog, we need to change the Scattering Density value. High values will make the fog thicker.
Note: Tracing depth also needs to be set to a higher number in order to see the fog effect. To avoid higher render times, we can enable Extended Tracing from Render Settings that will take care of that.