Thanks Demian for the upvote!
Yep used the different grass height in the test images ( hence the different patches on the stacked planes on the left)
It would be great if this could be added to a dedicated feature as I have the feeling Rhino isn't the best suited textures setting wise.
Ideally we would have 2 slots : one for transparency and one for height (bump map as Gadget rightly mentioned), but that's obviously a complicated thing..
Could environment be used for the height and transparency as what it should be for transparency? So we could both controlled height and areas
Obviously I understand how complicated all those things are to implement.. anyway again thanks for all the listening for the feedback!