vtlib Paging of Tilesets

You can easily handle elevation much larger than RAM, and imagery larger than texture RAM, by using tilesets.  VTBuilder is the easiest way to create tilesets, and libMini is used directly by vtlib to render them.

Data size

Tilesets can get extremely large on disk, which makes them difficult to move around.
You can reduce this greatly with compression, both by using texture compression for imagery (e.g. DXT) and/or further compressing with common archival tools like 7zip.

Example: a 2.4 GB imagery tileset

MB percent  
2396.8 100% uncompressed
 426.7 18% 7zip
300.3 12.5% DXT1 (1/8 size of uncompressed)
139.0 5.8% DXT1 and then 7zip