Photo Jim is correct. I've even ran into a problem like this while shooting at ground level with our Sony A7s. There were multiple buildings in my shot but I was closer to some buildings that others when I set up my tripod. I leveled the tripod and it made the buildings I was closest to look straight but the others looked slightly tilted. Had a devil of a time explaining it to my boss. SanCap is not totally wrong though either. I've noticed when photographing buildings with out I1 and X3 camera, depending on how close we are to things and how tilted the camera is, there can be distortion of square or rectangular objects like buildings. My suggestion, even if viewing the video, as you shoot, through a small iPhone or Android, look carefully at where you are in relationship to the objects you want to shoot before you press the button. Also, shoot multiple shots, move the quad copter a little, shoot some more, do it again and again if you have the time and battery power. I'd rather have just one or two perfect shots out of dozens, than a few that look odd and that the client doesn't understand why they're "off."
