Recently I'm working at the function of draping vectors to the terrain. I read the source code of osgEarth1.3(which means much less code for me compared to the latest version) and found it uses class osgSim::Overlay. However, when I dive into osgSim::Overlay, I can't really get what this class wants to do. The only thing I know about osgSim::Overlay is that it captures a texture and puts it on the terrain. Does anyone know about how the texture image is produced? Or is there some paper which explains the algorithm? Please help me know.
The texture for an overlay is typically created using an RTT (render-to-texture) camera. How these work is beyond the scope of this forum, but you can find discussions and examples in the OSG distribution and on the osg-users forum.