RE [gdal-dev] Translating between UTM and Geographic

[Steve.Toutant at inspq.qc.ca]

The problem might not be in your code but in the WKT projection 
information (sSpRefParams).


Steve Toutant, M. Sc.
Analyste en géomatique
Secteur environnement
Direction des risques biologiques, environnementaux et occupationnels
Institut national de santé publique du Québec
945, avenue Wolfe
Québec, Qc G1V 5B3 
Tél.: (418) 650-5115 #5281
Fax.: (418) 654-3144
steve.toutant at inspq.qc.ca
http://www.inspq.qc.ca
 




"Henneke, Amanda M" <amanda.m.henneke at boeing.com>@lists.osgeo.org 
Envoyé par : gdal-dev-bounces at lists.osgeo.org
23/09/2009 11:16 AM

A
"gdal-dev at lists.osgeo.org" <gdal-dev at lists.osgeo.org>
cc

Objet
[gdal-dev] Translating between UTM and Geographic








Hello all-

I'm trying to figure out how to reproject some points from a UTM 
projection to Geographic (WGS84) projection.  This works fine when I'm 
working in UTM Zone 12 with NAD83.  When I try the same code for Zone 11 
NAD27, I get a slight shift in the points (to the east) and an extremely 
slight shift up (to the north).

I've included the following code as it stands now, I've tried all sorts of 
things thinking that I need to somehow include more information for the 
new spatial reference (the destination SR), and so far I'm coming up 
empty...

Anyone have any ideas what I'm missing?

Where sSpRefParams is a string that contains the WKT projection 
information from a valid layer...

srOld = new OSGeo.OSR.SpatialReference(sSpRefParams);

srNew.SetGeogCS("Geographic Coordinate System", 
OSGeo.OSR.Osr.SRS_DN_WGS84, OSGeo.OSR.Osr.SRS_DN_WGS84, 
OSGeo.OSR.Osr.SRS_WGS84_SEMIMAJOR, OSGeo.OSR.Osr.SRS_WGS84_INVFLATTENING, 
"Greenwich", 0.0, "degree", 0.0174532925199433);

ctTransform = new OSGeo.OSR.CoordinateTransformation(srOld, srNew);



Amanda M. Henneke
IG/DB Tools - TSS Capability Center
Boeing - St. Louis
314-777-6856



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