This page provides an outline of the different methods for using materials in V-Ray for Unreal.
Overview
V-Ray for Unreal incorporates several different means to produce and use materials in Unreal. Materials can come from Unreal itself using the V-Ray Material Instance Asset. The Render material from .vrscene feature enables the use of the original material from the imported vrscene. More powerful and versatile materials, created by external software using V-Ray, can be exported to .vrscene files that serve as External Material Libraries and used within V-Ray for Unreal.
V-Ray Material Instance Asset
The V-Ray Material Instance Asset is a material asset that enables you to easily create V-Ray materials in Unreal. For more details see the V-Ray Material Instance Asset documentation.
Render material from .vrscene
This feature allows you to switch between rendering the material that was set in Unreal Engine or the material that was stored in the .vrscene file. This opens the possibility to use various and more complex materials that were created outside Unreal but still render in V-Ray for Unreal (e.g. Blend materials, Carpaints, Subsurface materials, etc.). For more details see the Render material from.vrscene documentation.
External Material Libraries
If you would like to use a material that is not yet supported, you can take advantage of the functionality to map Unreal materials to V-Ray materials created with another V-Ray plugin (e.g. materials coming from V-Ray for Maya, V-Ray for 3ds Max, etc.). For this to work, the materials have to be exported as a .vrscene file (this would be the EML file). The mapping works by matching the name of a material in Unreal to the name of a material in the EML file. In addition, the materials in the EML file need to have a scene_name parameter set. This is the name that is used to match a material in Unreal. For more details see the External Material Libraries documentation.