Support for global terrain?

Hi, guys!
A global terrain is a virtually limitless terrain representing a certain fragment of Earth’s surface. It can be generated on the basis of ordinary raster images and/or GIS data. It is Geo-referened and the surface would be curved by earth curvature. This type of terrain can be successfully used for flight simulators: most of the time the plane remains at a very high altitude and low-resolution data is sufficient.