Re: earthdistance compass bearing

From: John R Pierce <pierce(at)hogranch(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: earthdistance compass bearing
Date: 2013-06-18 18:27:28
Message-ID: 51C0A690.1050208@hogranch.com
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On 6/18/2013 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?

calculating the angle between two points on the surface of a sphere is
non-trivial.

You'll probably need to use PostGIS for that, and the ST_Azimuth()
function, which returns angle in radians betweeen two points (multiple
by 180/PI to get degrees)

--
john r pierce 37N 122W
somewhere on the middle of the left coast

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