[postgis-users] I can't make sense of this.

Ronald Phillips rphillips at summitengineer.net
Thu May 20 09:55:31 PDT 2010

I want to provide a geometry that was input from Google Maps (SRID 3857)
for GPS units (SRID 4326). How should I do that?


I hated to post this, frankly. I know it's a "thinko;" I'm not
understanding the concept. If I describe a geometry in SRID 3857, then
it seems to me that that point would have a slightly different
description in SRID 4326. Instead, they're wildly different. So, I know
I am misunderstanding in some basic way. 





From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Emilie Laffray
Sent: Thursday, May 20, 2010 12:48 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] I can't make sense of this.


Why would you expect them to be similar? There are different sets of
Your first set of coordinates looks like wgs84 but you set the srid to
Google srid. 
It doesn't make sense.

	On 20 May 2010 17:38, "Ronald Phillips"
<rphillips at summitengineer.net> wrote:



40.28787)', 3857)


	AS goog, 



ST_GeomFromText('POINT(-81.064544 40.28787)', 3857)

	                        , 4326)


	AS gcs


	3857 is "Google's" SRID, and 4326 is a fairly standard GPS SRID.
I'm getting this:


	Goog: "POINT(-81.064544 40.28787)";

	Gcs: "POINT(-0.000728215188753794 0.000361912093851508)"


	What am I doing wrong, that they're so different?


	Ronald Phillips, B.S., M.S.



	Summit County Engineer

	538 E. South St.

	Akron OH 44311




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