How to dynamic loading very large terrain?

I have a satellite image, about 30GB

  1. Unity3d cannot support this image, how to loading to unity3d?
  2. Terrain, first load the full screen new dragged out of the terrain, and the system can release has been towed away topography memory is loaded automatically when the mouse to drag the map.How to achieve?
  3. Any Plug-in ?

thanks!

This: http://rogerpugh.weebly.com/pterrain.html