osgEarth is a C++ terrain rendering toolkit. Just create a simple XML
file, point it at your imagery, elevation, and vector data, load it
into your favorite OpenSceneGraph application, and go!

osgEarth supports all kinds of data and comes with lots of examples to
help you get up and running quickly and easily.

Some optional requirements are recommended for enhanced functionality
and/or performance. They include:
    poco, protobuf, rocksdb
