I am going to buy Phantom 3 for survey of semi-residential area but I have some questions: My objective is aerial photography to capture very large area for showing as high resolution map image layer showing much more details than satellite image in mapping application. I want to fly the drone as fast as possible but not too fast to degrade picture quality. I want to fly it as high as possible but not too high to degrade picture quality. The reason for this is to avoid naughty people seeing the drone and shooting it down. What is the best speed and altitude for above scenario? Approximate how long it will take to photograph entire one square mile area?