Please show example of texture in Dirt Radius

[richard_aubin]

I see some 3DS Max users using a texture in the Radius slot, and I would like to see an example of how to do this in VRay for Rhino.

https://youtu.be/38-TGp5QCMY?t=451

[Grigio18]

Here it is, same method...

[richard_aubin]

The objective is to create a procedural texture in a similar method as the author of the video I shared. My query is specifically about how to use a bitmap/texture in the radius texture slot to influence the radius of the Dirt texture.