VS: [mapserver-users] projection = geographer's pain

[Rahkonen Jukka]

Hi,

Have you double-checked that your map extent correspods with the map projection?
Or if you could send your whole mapfile I am pretty sure that you will get a final answer to your problem.

-Jukka Rahkonen-

> -----Alkuperäinen viesti-----
> Lähettäjä: mapserver-users-bounces at lists.osgeo.org 
> [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta 
> Monier Clement
> Lähetetty: 27. lokakuuta 2008 13:39
> Vastaanottaja: 'Pietro Giannini'; mapserver-users at lists.osgeo.org
> Aihe: RE: [mapserver-users] projection = geographer's pain
> 
> 
> Thanks for your answers Roger & Pietro.
> 
> I've followed your advice by trying these 4 test-cases :
> 
> 1) 
> Map proj set to :   "init=epsg:3785" (web spherical Mercator, 
> manually added
> into espg file)
> Layer proj set to : "init=epsg:4326" (latlon wgs84, proj system of my
> shapefiles)
> 
> => got a blank map
> 
> 2)
> Map projection set to : "init=epsg:4326"
> Layer projection set to : "init=epsg:4326"
> 
> => got a map
> 
> 3)
> Map projection set to : "init=epsg:3785"
> Layer projection set to : "init=epsg:3785"
> 
> => got the same map as 2)
> 
> 4)
> Map projection set to : "init=epsg:4326"
> Layer projection set to : "init=epsg:3785"
> 
> => got a blank map
> 
> I've also tried with another well-known existing epsg 
> proj-system (instead of the manually-added 3785 code), but 
> got the same results.
> I've made other attempts by replacing "init=3785" by full 
> description proj-string like "+proj=longlat +ellps=WGS84 
> +datum=WGS84 +no_defs  no_defs"
> or "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 
> +x_0=0.0 +y_0=0
> +k=1.0 +units=m +nadgrids=@null  no_defs"
> But it didn't change anything...
> 
> It seems that :
> - a map is drawn only if the map's and layer's proj-systems 
> are the same.
> - the output projection is always overridden by the shapefile 
> system, no re-projection is done anyway.
> 
> Let me know if you have any further leads to solve this issue.
> 
> Thanks for your help
> 
> Clément	
> 
> -----Message d'origine-----
> De : mapserver-users-bounces at lists.osgeo.org
> [mailto:mapserver-users-bounces at lists.osgeo.org] De la part 
> de Pietro Giannini Envoyé : vendredi 24 octobre 2008 21:40 À 
> : mapserver-users at lists.osgeo.org Objet : Re: 
> [mapserver-users] projection = geographer's pain
> 
> I can confirm that projection is often a pain!
> 
> However, the problem may be in the projection of the layer.
> 
> The PROJECTION section in a layer declare the projection of 
> the data source of this layer, while the PROJECTION on the 
> map level is the projection wich you want to show the whole 
> map. So you can overlay more data sources in different 
> projection in a single map.
> 
> Try to set the layer PROJECTION as "init=epsg:4326".
> Let us know...
> ciao
> ........................... pg
> 
> 
> --
> Pietro Giannini
> Bytewise srl - Area GIS
> 41°50'38.58"N 12°29'13.39"E
> 
> 
> 
> 
> On Ven, Ottobre 24, 2008 16:55, Monier Clement wrote:
> > Hi,
> >
> >
> >
> > I'm running MS4W v2.2.8 (including MapServer 5.2) on windows.
> >
> > My datasource is shapefiles with WGS84 projection (epsg:4326).
> >
> > I would like MapServer to render these data into a "Web (spherical)
> > Mercator" projected map (epsg:3785) in order to perfectly 
> overlay the
> > GoogleMaps tile images (for the moment, my maps are slightly shifted
> > north.)
> >
> >
> >
> > I've added this string at the end of the file "epsg" in 
> /ms4w/proj/nad :
> >
> > <3785> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 
> +lon_0=0.0 +x_0=0.0
> > +y_0=0 +k=1.0 +towgs84=0,0,0,0,0,0,0 +units=m 
> +nadgrids=@null +no_defs <>
> >
> >
> >
> > But I don't know how to modify my request and mapfile in 
> order to get the
> > correct map.
> >
> > I've tried many combinations so far but with no success until now.
> >
> >
> >
> > Do I have to change the projection system of my shapefiles ?
> >
> > Is MapServer able to change projection between input and output ?
> >
> >
> >
> > Request : "&SRS=epsg:3785"
> >
> >
> >
> > MapFile :
> >
> >
> >
> > [Map section]
> >
> >   METADATA
> >
> >     "wms_srs"   "EPSG:4326 EPSG:3785" # is this correct ?
> >
> >   END
> >
> >
> >
> > PROJECTION
> >
> >    "init=epsg:3785" # is this correct ?
> >
> > END
> >
> >
> >
> > [Layer section]
> >
> >   METADATA
> >
> >     "wms_srs"   "EPSG:3785" # is this correct ?
> >
> >   END
> >
> >   PROJECTION
> >
> >    "init=epsg:3785" # is this correct ?
> >
> >   END
> >
> >
> >
> > With these settings, the pictures I got from MapServer are 
> still shifted.
> >
> >
> >
> > Thanks for your help
> >
> >
> >
> > Clement
> >
> >
> >
> > _______________________________________________
> > mapserver-users mailing list
> > mapserver-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >
> 
> 
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