[Proj] Coordinate change transforming to EPSG:4326

[Noel Zinn]

In this regard, be aware of EPSG dataset coordinate operation method 1024
("Popular Visualization Pseudo Mercator"), which solves this problem
correctly by defining a new projection.

Section 1.3.3.2 of Guidance Note 7-2 at www.epsg.org

Noel

-----Original Message-----
From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Hamish
Sent: Wednesday, May 27, 2009 1:43 AM
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] Coordinate change transforming to EPSG:4326


Miguel wrote:
> I am using proj.4 as part of PostGIS. Version 1.3.1 of
> postgis included PRO Rel. 4.5.0, whereas version 1.36
> includes PROJ Rel. 4.6.1
> 
> When I transform a coordinate from EPSG:23209 to EPSG:4326
> I get the following results.
> 
> 
> In Postgis 1.3.1 (PROJ.4 Rel. 4.5.0):
> 
> "POINT(549556.009066526
> 4801796.3531214)";"POINT(-8.38839299999999
> 43.3657910268222)"
> 
> In Postgis 1.3.6 (PROJ Rel. 4.6.1):
> 
> 
> "POINT(549556.009066526
> 4801796.3531214)";"POINT(-8.38839299999999
> 43.3666118995462)"
> The second coordinate of the transformation to 4326 changes
> by 0.004 degrees (approx).
> 
> If I use cs2cs from command line (version proj446_win32), I
> get:
> 
> 
> -8.38839300     43.36661190
> 
> Why do I get a different result in postgis 1.3.1 and in
> postgis 1.3.6?
> 
> Why do I get the same result in PROJ4 4.4.6?

see
http://trac.osgeo.org/proj/wiki/FAQ#WhydoIgetdifferentresultswith4.5.0and4.6
.0


Hamish



      

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