This page gives some basic details about the Caustics Render Element and how it is used in compositing.
UI Path: ||Shading viewport|| > Shader Tree > Add Layer button > V-Ray Render Elements > V-Ray Additional Outputs > Caustics
This render element is enabled and controlled through the V-Ray Additional Outputs properties.
Enable Caustics – Enables the Render Element.
Name – Sets a custom name for the Caustics Render Element.
Deep Output – Specifies whether to include this Render Element in deep images.
Apply Color Mapping – Applies the color mapping options specified in the Color mapping rollout of the V-Ray Main Render Settings.
The Caustics Render Element is useful for changing the appearance of caustic elements after rendering in a compositing or image editing application. Below is an example of its use.
The VRayCasutics Render Element is added to the Beauty render to form the final image.