Portable Mapping Pods on Helicopters
Recently I was contacted by a helicopter operator in Tasmania to see if our portable mapping pods could be adapted to fit a Squirrel B3 helicopter bound for Antarctica over the summer. Our camera pods were initially designed to fit to the landing gear leg of a Cessna 172, so the obvious problem was where to mount the thing? After a bit of head scratching it was decided that the best place to fit the system would be the end of the skid. A small adapter bracket was engineered and the pod was fitted to this. Rest of the install was fairly painless as the system only relies on one cable that can be closed in the door simplifying cable routing.
Never having flown a camera on a helicopter before we had some initial concerns about the possible extra vibration from the helicopter rotors and how this may effect the imagery. While our camera pods do have a vibration isolation plate in them, this was designed around the expected engine vibration frequencies of a Cessna 172 not a helicopter. So we were unsure about how this would perform, and it turns out it performed fairly well, with no blur evident in the imagery.
In order to test the vibration and the demonstrate the accuracy of the system, a test flight was in order. In order to minimize aircraft costs a survey area close to the airport was chosen. We wanted to give the system a reasonable test, so an area of around 30 sqkm was chosen. Imagery was captured over this area at a GSD of 8cm, and a local surveyor collected 15 ground control points (GCP’s) to test the systems spatial accuracy. The system performed well and the resulting mosaic and digital surface model from the test flight can be seen below.