I was wondering if it is possible to use a pre-existing mesh as the heightfield for osgEarth, I can't see any support for it. What I would like to do is use osgEarth with a imagery loaded via gdal but the heightfield specified via our own mesh.
If there is no current support, would writing a new driver be the right way forward? Could that still support holes in the mesh?
You are correct; there is no support for a pre-existing mesh at this time. Doing this is not as simple as adding a new driver - a driver can only supply a parametric height field. So various upgrades/additions to the core would be required as well.
You are not the first person to ask for this feature. It will likely make it in there at some point.