Using dirt along with displacement?

[alexthg]

A couple question with vraydirt & displacement:

1. How to use vraydirt texture in vraydisplacement texmap? Well, I've tried already, but it doesn't work. The idea is to use vraydirt as mask around crevices & contact with other objects. For example, to mask the carpet displacement around carpet borders & contact with tables, chairs, etc.

2. Is there any way to make vraydirt ignore vraydisplacement? So the dirt will only take the original mesh in account, and not occluding the mesh generated by the displacement. For example, when using grass displacement, I don't want vraydirt to occlude the complex mesh generated with displacement, but only those crevices & areas in contact with other objects (such as when the lawn meets trees, curbs, etc).

[Neilg]

Not possible, at render time displacement may aswell be geometry and dirt is calculated at render time based on surrounding geo.

Ive taken to using normal maps because of this, send your displacement map through crazybump and it tends to do a pretty spot on job of it after a bit of tweaking. Tends to look so much better with real dirt on it that the slight drop in definition is worth it.

Works well with brick/hard sufaces, but you may have some trouble with grass. If you use the dirt to create edging, it may be worth getting into the habit of modeling it - after a bit of getting used to it, it looks really good.

[vlado]

You can do this if you first bake the dirt map with RTT and then use this in place of the actual vraydirt in the displacement.

Best regards,
Vlado