Clear material History when changing render engine

Dear users
Is there a way you can clear all material history when changing render engines?
Sometimes I need to change render engines from Brazil to Vray or Vray to Brazil or either to Rhino renderer-I want to clear all existing materials and reapply as sometimes the maps cant be found.
Also when a map cant be found when rendering how can I find what material is missing the map.

Cheers jahn

Do you have a material with which it regularly happens? Could you put that in a simple scene on a box and share the file along with all necessary bits and pieces?

No its more when you open someone else’s file who hasnt saved the materials and when you go to render there is a dialog box stating what maps etc are missing from the file-

  1. I want to clear all materials and maps
    2.I need to find which material is missing the map rather than hunting through all materials

The dialog has a button where you can both see what materials are in question, and allows you to select new inage textures.

The dialog should pop up already on opening of the file.

Does it not give you the information and change tool you need?

Does this n

If your rendering engine is using the modern rendering tools in Rhino - as, for example Brazil does, you just need to open the material editor, select all of the materials and delete them.

Unfortunately, VRay is not there yet, although they are working on it. For them, you will need to contact Chaos Group, because their material system is completely custom.