You're far too pessimistic (or maybe you don't know the field well). The problem of estimating the relative poses of the cameras responsible for a set of pho

You're far too pessimistic (or maybe you don't know the field well). The problem of estimating the relative poses of the cameras responsible for a set of photos is a long standing and essentially "solved" problem in computer vision. I say "solved" because there is still active research (increasing accuracy, faster, more robust, etc.) but there are decades-old, well known techniques that any dedicated programmer could implement in a week. If you're genuinely curious, look into structure from motion, visual odometry, or SLAM.