David Johnson at djx blog has created mattePassMaker, a script for Maya to create black and white matte renders using mentalray’s pass system… which means that many matte passes will take the same time as running one matte! Check out the djx page for a lot more info!
“You can use this script to create black and white matte renders using mentalray’s pass system which means that it takes no longer to render 100 mattes than it does to render one. And since the script makes it so easy to set up these passes you can render a separate matte for every object in your scene, if thats what you want, or for combinations of objects that you select or based on the materials that are assigned.”
