I was looking at this stack exchange question. How do I calculate the ground footprint of an aerial camera?

I'm trying to calculate the area a photo footprint captures depending on the elevation of a drone. This answer explains it very well, but I'm having trouble understanding the x and y-axis gimbal angle the answer describes.

In particular, for mapping applications a drone's camera is normally not directly pointing down, but instead point a bit forward, perhaps 10 or 15 degrees. I'm wondering if this is the x-axis or the y-axis. In most examples, both the x and the y axis angle are the same, but this doesn't make sense, since most drones, like the DJI Phantom 3 has a camera that only moves along the up and down axis.

Any help would be greatly appreciated.

  • That answer assumes the camera is tilted on two axes. Assuming your drone platform itself is level, your camera can only tilt on one axis. The answer to the other question also has some other fundamental problems that yields answers in which the hypotenuse of a right triangle is shorter than the length of the perpendicular sides! – Michael C Sep 1 '16 at 2:58

If I were going to calibrate a drone's image "footprint," assuming that the camera reports the gimbal angles (otherwise you have no way to make a measurement), I'd either hang or hover the drone over a calibrated target, such as tape marks on a driveway. Then take a few pictures at different gimbal angles and identify the image area covered by the tape marks. A little trigonometry will give you the footprints.

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