Well, let's see... I've invested a couple of thousand hours in small aircraft, and I've taken courses in photogrammetry and air photo interpetation... What altitude you have to fly at depends on what lens you use, and that depends a lot on what you have. Further considerations include, as you know, that wide angle lenses tend to have distortion and telephoto lenses tend to flatten subjects. Second, all lenses have a 'field of view/ distance', so you'll need to determine what that is for the lens you're using.
Next, traditional aerial photography is done using a camera mounted into a special hole in the belly of the aircraft, so that the images are more or less straight down. If you're shooting out the window, you're going to have to remember your analytical trigonometry to figure out the surface area on the ground. The other way is to shoot something that you know to be a specific distance on the ground, print the image, measure the distance on your print and use a ratio to get the scale at that altitude with that lens (ASL or AGL). From there you could extrapolate, but there's always going to be some error. For example, if you're shooting out the window, is every shot going to be at exactly the same angle? On each trip?
Finally, your pilot would know this, but if you're going to be flying over any built-up/ urban areas, you have to consider a minimum 500 foot AGL or the FAA will be on your butt.
So, why isn't this guy just buying existing aerial photography of the area and creating a photomosaic if necessary? I don't know how it works in the US, but I'm sure there's some gov't agency that has hard copy/ and or digital files of the area.
Mike.
Poll
