I'm not clear what you mean "your map is totally flat", nor what you intend to do with the Attribute, Light map, etc. If you use a Heightfield Load on the L3DT exported .TER file, it should load in fine. If it doesn't, that's problem #1 and we can try to address it. You would need to load Attribute, etc. maps separately *if* they're in a compatible image format, and what you do with them would depend on what you're trying to achieve. I'm not familiar with what L3DT is generating, so it's hard to say what they'd be useful for.
- Oshyan