This video tutorial goes through the steps to create and render custom permeable grass paving in Vray for Rhino. The key steps in this video can be found below:
00:00 - Introduction
00:40 - Creating a concrete material
02:25 - Adding a 'displacement map' to create the pavers
05:31 - Creating a grass material
05:56 - Using 'Vray Fur' to create grass strands
07:30 - Using a density map to control the placement of the grass/ VRay fur
09:27 - Tweaking the tile parameter to adjust the sizing of the pavers
10:50 - Using a custom paving pattern to control this effect