This page provides information about the Object ID Render Channel in V-Ray for Blender.
Overview
Two or more objects in the scene can share the same Object ID.
The Object ID Render Chanel creates selection masks based on Object ID that shows each object (by Object ID) in a solid unshaded color.
UI Path: ||V-Ray Node Editor|| > World > Render Channels > Matte > V-Ray Object ID
Properties
Enable Deep Output – Includes this render element in deep images.