[postgis-users] Amatuer question - Distance between two points

[Michael Signup]

Neat. Thanks very much Chris.

Michael

Date: Fri, 7 Nov 2008 07:25:59 -0600
From: kc5hhq at gmail.com
To: postgis-users at postgis.refractions.net
Subject: Re: [postgis-users] Amatuer question - Distance between two points

Michael,
  If your SRID is not in UTM, you will need to use the utmzone function to transform it into the correct UTM SRID. This will result in the distance being measured in meters.

Have a look at http://postgis.com/support/wiki/index.php?How%20to%20get%20distance%20measurement%20in%20meters%3F and http://postgis.com/support/wiki/index.php?plpgsqlfunctions

   
This is the query I use. My wkb_geometry is in SRID 4326.
Select distance(transform(wkb_geometry,utmzone(GeomFromText( 'POINT($lon $lat)', 4326 ))),transform(GeomFromText( 'POINT($lon $lat)', 4326 ),utmzone(GeomFromText( 'POINT($lon $lat)', 4326 ))))


On Fri, Nov 7, 2008 at 5:55 AM, Michael Signup <michael.signup at hotmail.com> wrote:












Hi,

This is probably a very simple question but I am unable to find anything to point me in the right direction.

I am trying to understand how I can make distance related queries with PostGIS. To do this, I am attempting to calculate the distance between:


in Lat/Long
Point A(-38.034031,145.201711) and Point B(-37.899854,145.087116)

I have tried several methods and am still getting the distance as 92072.62 (I don't know what units this is in, but I am trying to get it in meters).


Google Earth calculates the distance as 17.4 km (approximately).

Regards,
Michael




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