Another excellent source for great circle navigation formulae is Ed Williams' "Aviation Formulary" website at: http://williams.best.vwh.net/avform.htm. It's the best I've seen on the subject.
- Bill Thoen On Sat, Aug 12, 2006 at 10:43:53PM +0200, Just van den Broecke wrote: > Andy, > > Thanks! It works. > > best, > > --Just > > Just van den Broecke [EMAIL PROTECTED] > Just Objects B.V. tel +31 65 4268627 Skype: justb4 > The Netherlands http://www.justobjects.nl > > Andy Armstrong wrote: > > >On 10 Aug 2006, at 18:54, Just van den Broecke wrote: > > > >>For the experts: I am looking for a formula, preferably as Java > >>(Script)-code, to calculate the course between two lon/lat pairs as a > >>value between 0 (north), through 180 (south) to 360 degrees (like in > >>the values from a GPS RMC sample). I can calculate Great Circle > >>distance, but somehow couldn't find course-calculations Googling. > > > > > > From the gpsbabel sources: > > > >/* This value is the heading you'd leave point 1 at to arrive at point 2. > >* Inputs and outputs are in radians. > >*/ > >double heading( double lat1, double lon1, double lat2, double lon2 ) { > > double v1, v2; > > v1 = sin(lon1 - lon2) * cos(lat2); > > v2 = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(lon1 - lon2); > > /* rounding error protection */ > > if (fabs(v1) < 1e-15) v1 = 0.0; > > if (fabs(v2) < 1e-15) v2 = 0.0; > > return atan2(v1, v2); > >} > > > >It's C but it's not going to be hard to translate into JavaScript :) > > > > > -- > > > > > _______________________________________________ > Geowanking mailing list > [email protected] > http://lists.burri.to/mailman/listinfo/geowanking > _______________________________________________ Geowanking mailing list [email protected] http://lists.burri.to/mailman/listinfo/geowanking
