This page gives some basic details about the Refraction Glossiness render element and how it is used in compositing.
Overview
The Refraction Glossiness Render Element stores the image's refraction glossiness as a grayscale image that represents the degree of Refraction Glossiness set for materials in the scene. White areas have the most refraction glossiness, while dark areas have little.
The amount of refraction glossiness for a material is set by its Refraction Glossiness parameter. For example, V-Ray Material (VRayMtl) has a Refraction Glossiness parameter, and Skin Material (VRaySkinMtl) has parameters for primary and secondary refraction glossiness.
Attributes
The parameters for this render element appear in the Attribute Editor under Extra V-Ray Attributes.
Enabled – When enabled, the render element appears in the V-Ray Virtual Frame Buffer.
Deep output – Specifies whether to include this render element in deep images.
Filename suffix – The text added to the end of the rendered file, when saved as a separate file (e.g. myrender.reflGloss.vrimg).
This render element is not supported with V-Ray GPU rendering.