SV: [mapserver-users] Projection error, RT90 in MapServer

[Sofia Bryntse]

Hi Jukka, 

Wonderful! You fixed the problem, thank you very much! This solution saves me hours of work. :)

And you are right about the 'units=m' in the wgs84 projection, it works fine without it.

Regards,
Sofia
________________________________________
Från: Rahkonen Jukka [Jukka.Rahkonen at mmmtike.fi]
Skickat: den 22 januari 2010 16:06
Till: Sofia Bryntse; mapserver-users at lists.osgeo.org
Ämne: Re: [mapserver-users] Projection error, RT90 in MapServer

Hi,

How about these parameters?


"+proj=tmerc +lat_0=0 +lon_0=15.80827777777778 +k=1 +x_0=1500000 +y_0=0 +ellps=bessel +units=m +towgs84=414.0978567149,41.3381489658,603.0627177516,-0.8550434314,2.1413465,-7.0227209516,0 +no_defs"

Taken from http://www.zonefivesoftware.com/SportTracks/Forums/viewtopic.php?t=3543&postdays=0&postorder=asc&start=25

By the way, I suppose the unint in your WGS84 definition are wrong. Maybe you do not need the line at all.

> PROJECTION
>       'proj=longlat'
>       'ellps=WGS84'
>       'datum=WGS84'
>       'no_defs'
>       'units=m'
> END


-Jukka-


-----Alkuperäinen viesti-----
Lähettäjä: Sofia Bryntse [mailto:Sofia.Bryntse at et.slu.se]
Lähetetty: pe 22.1.2010 16:09
Vastaanottaja: Rahkonen Jukka; mapserver-users at lists.osgeo.org
Aihe: SV: [mapserver-users] Projection error, RT90 in MapServer

Hi Jukka,

Thank you, I tried adding your line to my RT90 projection parameter list now, but it didn't help. The point moved 50 meters or so, but not in the right direction. (See attached screenshot.)

Regards,
Sofia
________________________________________
Från: Rahkonen Jukka [Jukka.Rahkonen at mmmtike.fi]
Skickat: den 22 januari 2010 11:16
Till: Sofia Bryntse; mapserver-users at lists.osgeo.org
Ämne: Re: [mapserver-users] Projection error, RT90 in MapServer

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
> --
> View this message in context:
> http://n2.nabble.com/Projection-error-RT90-in-MapServer-tp4438
> 959p4438959.html
> Sent from the Mapserver - User mailing list archive at Nabble.com.
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> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
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>

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