Vray Opacity map

Leaves, feathers, and many other things like those would be a pain to model. So the use of opacity masks have been used on grids to give a quick version of these things.

Its the same principle in VRay material but it would be setup slightly different seeing as how there is no opacity slot. For this we use the refract slot and set the IOR to 1. That takes care of your opacity.

A common mistake in the standard material with this method is people forget that if they want to have specular highlights they will need to use a mask in the specular slot to kill the highlight on the supposedly empty transparent areas. With VRay material reflections are used for specular highlights so we will need to add the mask to the reflection slot instead.