The texture replacement from the materials editor is the perfect solution. Thanks Gaieus! monks

Wow, thanks a lot for this. I'll give it another go later when I get home following your instructions. Yes, I found quite a number of posts on this but the solution seemed to be something of a moving target as things have changed over time. I'm using drape in the sense that it's used in the GIS industry (as opposed to 3D modelling)- draping a texture over a heightfield (I guess that means orthographically projecting a texture onto it). The draping of geometry sounds very useful too. I did try to do this but I had trouble setting up the rectangle, but I've learned a few more things since then. Another problem I may have is that some of my models placed onto the terrain have become grouped somehow with the terrain mesh- I posted about this elsewhere. I may need to resolve that issue first. Dunno. monks