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

[Ronald Phillips]

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. 

 

Ron

 

________________________________

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
coordinates.
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:

	SELECT   

	            ST_AsText(

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

	                        ) 

	AS goog, 

	            ST_AsText(

	                        ST_Transform(

	
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.

	Programmer/Analyst

	 

	Summit County Engineer

	538 E. South St.

	Akron OH 44311

	330.643.8061

	http://www.linkedin.com/in/rwphillips

	 

	
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