Understand at which screen pixel TerrainQuad mountain peak get rendered

Currently I successfully render TerrainQuad based on real Digital Elevation data. I am able to position the camera into any Earth coordinate (latitude, longitude). I also have the meta information of the coordinates of the mountain peaks around.

I need to understand if these peaks are visible at the render and if they are visible - at which pixels of the rendered image do they appear. How can I do this?

https://dl.dropboxusercontent.com/u/14685507/pic.png

Thank you all in advance!