Re: RE: [mapserver-users] Gauss-Krüger

[Rahkonen Jukka]

Hi,
 
Your projectin setting is likely to give you unpredictable results, because init:epsg:26915 means
<26915> +proj=utm +zone=15 +ellps=GRS80 +datum=NAD83 +units=m +no_defs  <>
and now you are giving additional, different definitions for the type of projection, ellipsoid and datum.
 
What do you know about your old maps?   Obviously they were not originally in digital format but they have been scanned later, oriented to North-South and georeferenced with world file or something?  It is quite possible that you can find out the exact projection that was used for producing the map but it is a good start that you know it is Gauss-Krüger.  Below are two proj4 strings for Gauss-Krüger projections 
 
# DHDN / 3-degree Gauss zone 2 (deprecated) German
+proj=tmerc +lat_0=0 +lon_0=6 +k=1 +x_0=2500000 +y_0=0 +ellps=bessel +datum=potsdam +units=m +no_defs  <>
#Finnish KKJ
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  <>
 
What you need to chase up are
proj=tmerc #this is clear, Gauss-Krüger is a transverse Mercator projection
lat_0       #origin of latitude
lon_0        #origin of longitude, the central meridian of the projection zone
k             #scale factor, I suppose it is usually 1 in European Gauss-Kruger projections
x_0         #false easting in meters
y_0         #false northing in meters
ellps       #name of the ellipsoid; may be hard to find an accurate equivalent to 1908 situation
datum     #name of the datum; same as above
towgs84  #affine transformation parameters, usually either datum or towgs84 are needed
 
 
-Jukka Rahkonen-


________________________________

	Lähettäjä: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta Daiane Fraga
	Lähetetty: 16. marraskuuta 2010 13:02
	Vastaanottaja: Fuchs Juan Carlos; mapserver-users at lists.osgeo.org
	Aihe: RE: RE: [mapserver-users] Gauss-Krüger
	
	
	Hi,
	
	I understand what you say. But this is not my question. I'm with a map in a coordinate system outdated (the maps are dated from 1908). And I'm using an application that interacts with Google Maps, which has caused problems. Did you know how to do some kind of conversion from the Mapserver?
	We can do a conversion to the WGS 1984, but it has to be done manually for each map.
	I'm not sure that may maps have a known Mapserver projection. 
	
	I'm using this:
	    PROJECTION
	        "init=epsg:26915"
	        "proj=latlong"
	        "ellps=WGS84"
	        "datum=WGS84"
	    END
	
	
	Thanks!
	
	Daiane Fraga
	
	
	
	
	
	---------- Forwarded message ----------
	From: Fuchs Juan Carlos <jfuch at indec.mecon.gov.ar>
	Date: 2010/11/12
	Subject: RE: [mapserver-users] Gauss-Krüger
	To: Daiane Fraga <daiane.a.fraga at gmail.com>
	
	
	
	Hi Daiane
	You have to find in Prij.4 the right EPSG code for your maps
	in wich country / region are you interested?
	 
	yust to sart with ...
	 
	in the .map you have to insert two groups of code
	 
	in the header (first zone) goes the poyection of the map you are producing
	PROJECTION
	  "init=epsg:heregoesyourcode" 
	END
	 
	for each Layer you call to build the map
	Layer
	....
	PROJECTION 
	  "init=epsg:heregoesyourcodeof thesourcelayer"
	END
	....
	end
	 
	hope it help someway
	Cheers
	JC
	 

		-----Mensaje original-----
		De: Daiane Fraga [mailto:daiane.a.fraga at gmail.com]
		Enviado el: Viernes, 12 de Noviembre de 2010 12:03 p.m.
		Para: mapserver-users at lists.osgeo.org
		Asunto: [mapserver-users] Gauss-Krüger
		
		
		Hello,
		
		Did someone have any problems using Mapserver with Gauss-Krüger?
		I know that Mapserver is compatible with proj.4 library and the proj.4 library supports Gauss-Krüger. But I dont know how to use it. 
		Somebody could help me?
		
		Thanks.
		
		Daiane
		
		
		


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