Stuart > On Thu, Nov 4, 2010 at 11:32 AM, I wrote: > > Hi All, > > > > I recently came across http://www.marinetraffic.com/, which tracks > > shipping by means of their AIS transmitter, which all vessels over 299 > > gross tonnes must carry. > > > > The data is transmitted by radio and includes position, speed, course, > > rate of turn, as well as the vessel type, dimensions etcs.. The > > project collects the data from various volunteer receivers and > > collates it into a DB, and provides mash-ups over Google maps etc. > > > > I think there could be a very nice little project to incorporate a > > data feed from their server through a proxy and into our MP network, > > displaying marine traffic in real-time. This would completely obviate > > the need for AI shipping routes, and at a stroke, the sea in FG would > > become accurately populated. > > Having a bit of spare time over the weekend, I put together a pretty > simple perl script to act as a proxy between the marinetraffic website and > FlightGear. > > At a high level the proxy works as follows: > > 0) FG is pre-provisioned with 40 AI ships at start of day > 1) The script gets the current aircraft position from the property system > over > the telnet interface > 2) The script make an HTTP request to marinetraffic.com to get all the > ships > within a 1 degree x 1 degree square centred on the aircraft position. > 3) For each of the ships, the script sets the type, position, speed > and heading of an > AI ship with the data using the telnet interface again. > > The resulting screenshot isn't particularly impressive, but it does look > more > realistic than the distribution and heading of the normal > materials.xml random ships: > > http://www.nanjika.co.uk/flightgear/ships.jpg > > The screenshot shows a couple of container ships (one with a tug at > the front which > has the wrong model) making their way up the Firth of Forth near > Edinburgh. In the > distance you can just make out a ship berthed at Grangemouth. > > There are a couple of limitations with this approach > - We have to pre-define the number of AI ships in an AI scenario. I've got > 40 > on my system, but I don't have a good feel for what the overhead of each > AI > ship is. If the script finds more than 40 ships when searching, it reduces > the > search area and tries again. It would be much easier if we could define AI > objects at runtime. > - The telnet interface is very slow. It takes a couple of minutes to read > and > write the various properties. > - The current proxy causes a per-client load on the marinetraffic website. > I've > emailed for permission to use the data feed, but I doubt they'll be > too happy if we > were to integrate this into FG itself and have a couple thousand > clients requesting > data every couple of minutes. I think some approach which uses the raw > NMEA data > to get and then feeds it into the MP network would be better. > Unfortunately its not > clear how we can do that. > - Close to shore, ships seem to change their course such that a > snapshot of position, > speed and heading every couple of minutes is insufficient so we get > "jumps" with each > update. I think a better model might be to use the data as a sequence > of waypoints, but > I haven't investigated to see how easy that would be to implement. > > I've emailed the marinetraffic website for permission to use the XML > feeds that I've > reverse engineered and to see if they are interested in helping us with > some raw > data. > > Once I've permission I'll put together a package with the proxy and > the various other > changes so people can have a play. >
That looks like very good work so far. Let's hope you can make more progress. The way ahead that you have outlined looks promising. Vivian ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
