[mapserver-users] Projection error, RT90 in MapServer

[Rahkonen Jukka]

Hi, 

Have you tried adding 'towgs84=0,0,0,0,0,0,0' also to RT90 definitions?

-Jukka Rahkonen-


> -----Alkuperäinen viesti-----
> Lähettäjä: mapserver-users-bounces at lists.osgeo.org 
> [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta Fia
> Lähetetty: 22. tammikuuta 2010 10:56
> Vastaanottaja: mapserver-users at lists.osgeo.org
> Aihe: [mapserver-users] Projection error, RT90 in MapServer
> 
> 
> Hello,
> 
> I have a problem showing data in the former Swedish standard reference
> system RT90 2,5 gon V. The point is projected ~250 meters 
> northwest of where
> it should be. I have used the projection parameters for MapServer from
> Spatialreference.org.
> 
> The underlying map projection is SWEREF 99 TM (the new 
> standard Swedish
> reference system), with the following projection parameters:
> PROJECTION
> 	'proj=utm'
> 	'zone=33'
> 	'ellps=GRS80'
> 	'towgs84=0,0,0,0,0,0,0'
> 	'units=m'
> 	'no_defs'
> END
> 
> I have then tested to pinpoint an intersection, in both 
> WGS-84 and RT90, but
> the RT90 point does not end up where it should be.  I have 
> double checked
> that the RT90 coordinates are correct by transforming them to 
> WGS-84. See my
> attached screenshot.
> http://n2.nabble.com/file/n4438959/rt90_mapserver_error.jpg 
> 
> For the WGS-84 point I have the following projection parameters:
> PROJECTION
> 	'proj=longlat'
> 	'ellps=WGS84'
> 	'datum=WGS84'
> 	'no_defs'
> 	'units=m'
> END
> 
> And the RT90 point has:
> PROJECTION
> 	"proj=tmerc"
> 	"lat_0=0"
> 	"lon_0=15.80827777777778"
> 	"k=1"
> 	"x_0=1500000"
> 	"y_0=0"
> 	"ellps=bessel"
> 	"units=m"
> 	"no_defs"
> END
> 
> I have also tried all the other RT90 projections provided by
> Spatialreference.org, just to see if any of them would work 
> better, but
> without luck.
> 
> Have I made a mistake somewhere, or are there any suggestions 
> of why this
> error occurs? I'm out of ideas. 
> 
> Regards,
> Sofia
> -- 
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> 959p4438959.html
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