The Raw Diffuse Filter Render Element is similar to the Diffuse Render Element, except it is not affected by Fresnel falloff. The result is a solid mask showing the pure diffuse color as set in the V-Ray Material's settings.
To use render elements, select from the Available render elements column and click the Add button to add the passes you wish to generate at render time. When you render the scene, the added render elements listed in the column on the right, will also render, which can be viewed from the VFB window's channel drop-down menu.
For more information on the parameters on this dialog, see the Render Elements tab page.
