In the context of greening the inland shipping industry I am analyzing GPS data on moving ships. For these ships I would like to separate the data for upstream/downstream movement (up/down river). This turns out to be less than straightforward.
I was wondering if someone might have a good idea of doing so.
The best I was able to come up with so far:
- Make a list of GPS markers (manually) that tracks each (main) river and compare each ships location/motion with the markers: should work but marking the rivers/large open water sections might turn out to be impractical.
- Look at the overall change in GPS location and see if the ship has moved towards/away from the source of the river: would be inaccurate for small ship trips and/or bendy rivers.
The first approach seemed promising to me but I wonder if one could somehow make use of existing maps and somehow use these?
Edit: The current plan is to extract waypoints for the typical ship-routes from a waterway map. These waypoints will have an id, the GPS lon/lat and the local upstream angle. To find out whether a ship is moving upstream we simply have to find the nearest waypoints and compare its angle of movement with that of the local upstream angle as given by the waypoint. I will let you know if we succeed and if so how.