The code for azimuth on a sphere isn't so gnarly you couldn't whip it up in plpgsql, http://trac.osgeo.org/postgis/browser/trunk/liblwgeom/lwgeodetic.c#L924 P. -- Paul Ramsey http://cleverelephant.ca http://postgis.net On Tuesday, June 18, 2013 at 11:16 AM, Jeff Herrin wrote: > I don't need it to be too accurate. We're pushing hotel info into the GDS (sabre, expedia, orbitz, etc). They require airport info relative to the hotel. Example: DFW is 25 miles NW of the property. I thought about just faking it...comparing the hotel's lat/long from the airports. I can probably get N,S,E,W reliably enough, but i'm not sure at what point N becomes NW, etc. That just seems like a really crude bad way to do it, but the alternatives seem unnecessarily complex. I found some examples that use bearing but they all take headings in degrees (which im not seeing in earthdistance). I guess I'm going to have to either setup postGIS or brush up on my trig. > > thanks, > altimage > > From: "Steve Crawford" <scrawford@xxxxxxxxxxxxxxxxxxxx (mailto:scrawford@xxxxxxxxxxxxxxxxxxxx)> > To: "Jeff Herrin" <jeff@xxxxxxxxxxxxx (mailto:jeff@xxxxxxxxxxxxx)> > Cc: pgsql-general@xxxxxxxxxxxxxx (mailto:pgsql-general@xxxxxxxxxxxxxx) > Sent: Tuesday, June 18, 2013 11:37:10 AM > Subject: Re: earthdistance compass bearing > > On 06/18/2013 10:42 AM, Jeff Herrin wrote: > > I'm trying to get a compass bearing (N,S,NW,etc) using earthdistance. I can successfully get the distance between 2 points using either the point or cube method, but I've been struggling with getting the bearing. Any tips? > > > PostGIS has some functions that may be of use but might be overkill depending on your use but I don't see anything in earthdistance. > > What are you trying to solve? > > It's one thing if you are looking for a one-degree-accurate magnetic-variation-compensated great-circle heading for a 6,000km flight using WGS84 projection (initial-heading, of course, as it will vary over the course of your travel). > > If you just want to be accurate to eight compass-points over a few city-blocks then simple trig is probably more than sufficient. > > Cheers, > Steve -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
