This is my first post.
FYI.
Over the last couple of weeks there have been 2 new Blender add-ons to import DTMs/DEMs.
The first, written by Tim Spriggs from HiRise, imports HiRise DTMs into Blender.
The add-on is now part of the Blender 2.56a Beta release and is available at:
Download Page
The Blender Wiki page for the add-on.
I am a beginner with Blender but here are 2 of my attempts with the add-on.
I am using an XP Pro box with 2GB of ram.
I am still working on the colors and lighting.
Zumba Crater
Victoria Crater
The second add-on, written by Valter Battioli, imports LRO Lola and MGS Mola data.
This add-on is still in development.
BlemderArtist.org thread.
The Blender Wiki page for the add-on.
I just started playing with this one.
Dave