Rails looks ideal. There is one issue I have with any set up like this though, and that is the difference between where the drone is and where it thinks it is. GPS seems to be out by up to 2m on any given day and that has been almost fatal on several occasions.
What I would like is to be able to draw a rail/waypoint route etc, whether it be with your app or Litchi (DJI is less of a problem with its insistence that you prefly the route) and adjust the entire route (maybe marquee select and drag) to allow for the GPS error. (Or for the app to adjust it for me)
For example, I had to fly down a tree-lined drive recently. The route was drawn as I wanted it flown but the GPS was out by about 1 metre. Not only did I shave a tree, the video looked amateurish.
I would like to draw a spot on the map and tell the drone to go there. Then once it's where it's been told to go, I could tell it where it actually is and adjustments could be made. So in my example I could tell it to go to the middle of the drive; it would actually go about 1m to one side and I could then point on the map where it really is. It would then adjust the route accordingly. That's my dream.
Or I could just fly high like everyone else, but I'd be looking for another job.
(eta did I just confuse everybody with that 'explanation'?)
That makes sense John! GPs inaccuracies do cause issues but the trouble with letting you tell the drone where it is, is that it could be fatal if you pick a wrong spot. But we can add some validation checks to make sure you're within a certain range. Another way to do it is to just be able to displace the path and shift it around the map, since you'll only need to make relative changes. Do you like the DJI "waypoint recording" system ? That could be a potentially useful concept here.