My brother and I have a land surveying company and I'm in line patiently to take/pass my test and get my part 107 exemption in order to use the drone in our business. I am a huge proponent of the open source software community I have already found a program (VisualSFM) to take my photos and generate a dense point cloud for topo and 3d modeling. My challenge now is adding Ground Control Points (GCP's) to my point clouds to give real world values to my topo maps (as opposed to relative) I also Teach part time at a small private school that meets in our building and am considering incorporating Drones into our curriculum. (Coding, basic photogrammetry, etc.) Any ideas on adding Ground Control Points?