dirtmap
The Dirtmap is an advanced ambient occlusion shader for Mental Ray 3.2+.
The package consists of the Dirtmap.xsiaddon and all the files contained within it, a short documentation and the source code, so you can modify it to your heart's content.
The package also contains all files necessary to make it work with Maya.
For a more detailed description, help files and credits please take a look at
the files enclosed.
You can download it here:
Please follow the instructions enclosed for how to install.