[mapserver-users] Re: Mapserver WMS seem not to read +towgs84 parameters

[Rahkonen Jukka]

I forget to mention that I am using epsg:3067 in my WMS requests while image data is in epsg:2393 so Mapserver for sure is reprojecting. 
 
-Jukka-
 
________________________________

Lähettäjä: Rahkonen Jukka 
Lähetetty: 3. maaliskuuta 2009 14:59
Vastaanottaja: mapserver-users at lists.osgeo.org
Aihe: Mapserver WMS seem not to read +towgs84 parameters



	Hi,
	 
	I am using  Mapserver version 5.2.0 from MS4W delivery through WMS 1.1.1.  and I was now trying to add the missing +towgs84 parameters for the Finnish epsg:2393 projection.  I located the epsg file from MS4W\proj\nad directory and edited it from this:
	# KKJ / Finland Uniform Coordinate System
	<2393> +proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=3500000 +y_0=0 +ellps=intl +units=m +no_defs  <>
	 
	to this:
	# KKJ / Finland Uniform Coordinate System
	<2393> +proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=3500000 +y_0=0 +ellps=intl +towgs84=-96.0617,-82.4278,-121.743,4.80107,0.34543,-1.37646,1.4964 +units=m +no_defs  <>
	 
	However, adding +towgs84 parameters do not have any effect on the Mapserver output.  I am sure that this certain epsg file is read, because commenting out the <2393> line makes Mapserver to stop working with my mapfile.  In addition, I can make map to shift by editing +x_0 and +y_0 parameters.  I had even another try by skipping the whole epsg file by giving the projection directly in the layer definitions of my mapfile as 
	 PROJECTION
	      "proj=tmerc"
	      "lat_0=0"
	      "lon_0=27"
	      "k=1"
	      "x_0=3500000"
	      "y_0=0"
	      "ellps=intl"
	      "towgs84=-96.0617,-82.4278,-121.743,4.80107,0.34543,-1.37646,1.4964"
	      "units=m"
	      "no_defs"
	    END
	 
	Here I can see exactly the same behaviour.  Editing other parameters, like lon_0, x_0 and y_0 are really changing the output, while editing towgs84 parameters or leaving them out totally has no effect.  It looks to me that towgs84 parameters are not read at all, or all the parameters are interpreted as zeros.  However, I can't believe that this error wouldn't have been noticed by others so far.  So I am just giving the parameters in a wrong way?
	 
	The ESRI projection file at MS4W\proj\nad\ doest have <2393> definitions with a bit different towgs84 values.  Giving my  layer definition as "init=esri:2393" does not change anything, Mapserver does not use towgs84 parameters.
	 
	-Jukka Rahkonen-

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