Well I tried this "Last Shader" idea and it kinda works. In the image you can see some of the effects I'm after but a whole lot of undesirable elements. The population is set to "Displacement", my last shader, as its "Sit on terrain" and is distributed via a surface layer with a min height of 400 (200 fuzzy zone) and no Max height and a max slope of 20d degrees (no fuzzy zone). As you can clearly see there are areas that fall within these constraints but have no populations. I've tried with the slope constraints set to Final Normal, Terrain Normal and Planet/Object Normal. Final Normal (fig 5) and terrain Normal populate a small cluster on the top of the tower whilst Planet/Object Normal populates most of the sides as well (pretty sure I shouldn't be using the last one anyway).
Attached is the tgd file if any of you wizards fancy a go at it (you know who you are
) Just use your own model...
I'm just about giving up on this one. I don't think populations can go under overhangs, possibly because if they could you'd have two objects in the same vertical space or something like that. Anyone from PS care to chime in on this one
Richard