[Mapserver-users] WMS client re-projection errors

[Matthew Perry]

Tyler,
  The area is all in zone 10. And the nad83->nad27
datum shifts are certainly working. Maybe it's just
wgs84->nad27??

- matt

--- Tyler Mitchell <tjmitchell at riverside.bc.ca> wrote:
> Is the image crossing UTM zones?
> I recall reading something very recently that says
> Proj couldn't handle 
> datum shifts, but may now.  I'm not sure that's the
> issue though.
> 
> mapserver-users-admin at lists.gis.umn.edu wrote on
> 07/13/2004 12:31:20 PM:
> 
> > Hi folks,
> > 
> >   I have some shapefiles in UTM, NAD27, Zone 10
> > (epsg:26710) which I'm trying to overlay on a WMS
> > shaded relief layer from the USGS in Geographic,
> WGS84
> > (epsg:4326). The problem is a noticable distortion
> on
> > the y axis. Features line up at the center of the
> > image, but become more and more distorted as you
> move
> > above or below the center-line. 
> > 
> > These three images should capture the idea (keep
> your
> > eye on the peak in relation to the roads around
> it):
> > 
> > http://darkstar.rr.nu/download/mapserv1.jpg
> > http://darkstar.rr.nu/download/mapserv2.jpg
> > http://darkstar.rr.nu/download/mapserv3.jpg
> > 
> > 
> > It is almost as though the WMS image is vertically
> > compressed. However, when using a WMS image from
> > terraserver (nad83), the map is aligned properly.
> I am
> > running mapserver 4.2.0 on slackware linux with
> proj
> > 4.4.7 & the datum shift files. Perhaps the
> requested
> > WMS extents are not accurate because of the datum
> > shift?? Is there something unique to shifting from
> > wgs84 to nad27?? Anyone have any ideas?
> > 
> > 
> > The abbreviated mapfile is as follows:
> > -----------------------------
> > MAP
> > 
> >   PROJECTION
> >     "init=epsg:26710"
> >     # UTM zone 10, Nad27, meters
> >   END
> > 
> >   LAYER
> >     NAME "Shaded_relief"
> >     GROUP "bg"
> >     STATUS OFF
> >     TYPE RASTER
> >     CONNECTIONTYPE WMS
> >     CONNECTION
> >
>
"http://gisdata.usgs.net:80/servlet/com.esri.wms.Esrimap?
> > servicename=USGS_WMS_NED&"
> >     METADATA
> >       "wms_srs"    "EPSG:4326"
> >       "wms_title"    "Shaded Relief"
> >       "wms_name"    "US_NED_Shaded_Relief"
> >       "wms_server_version"    "1.0.0"
> >       "wms_format"    "image/png"
> >       "wms_group_title" "background"
> >     END
> >     PROJECTION
> >       "init=epsg:4326"
> >     END
> >   END
> > 
> >   LAYER
> >     NAME "Roads"
> >     STATUS OFF
> >     DATA "clip1"
> >     TYPE LINE
> >     TOLERANCE 2
> >     DUMP true
> >     METADATA
> >       "wms_title"    "Klamath Basin Roads"
> >       "wms_srs"    "EPSG:26710"
> >       "wms_abstract" ""
> >       "wfs_title"   "Klamath Basin Roads"
> >       "wfs_srs"    "EPSG:26710"
> >       "wfs_abstract" ""
> >     END
> >     CLASS
> >       NAME "Roads"
> >       STYLE
> >         SYMBOL 1
> >         SIZE 2
> >         COLOR 0 0 0
> >       END
> >     END
> >   END
> > 
> > END
> > ---------------------------------
> > 
> > 
> > Here is a link to a small, clipped shapefile if
> anyone
> > feels inclined to try it out...
> > 
> > http://darkstar.rr.nu/download/clip1.zip
> > 
> > 
> > ... and the urls to recreate the three sample
> images
> > are:
> > 
> > http://localhost/cgi-bin/mapserv?
> >
>
mode=map&map=/var/www/htdocs/klamath2/klamath2.map&mapext=594418.
> >
>
2128140883+4727975.646318736+602962.0885061937+4733853.
> >
> 945029724&mapsize=610+420&layers=Roads+Shaded_relief
> > 
> > http://localhost/cgi-bin/mapserv?
> >
>
mode=map&map=/var/www/htdocs/klamath2/klamath2.map&mapext=594411.
> >
>
1981378223+4730115.122579895+602955.0738299277+4735993.
> >
> 421290884&mapsize=610+420&layers=Roads+Shaded_relief
> > 
> > http://localhost/cgi-bin/mapserv?
> >
>
mode=map&map=/var/www/htdocs/klamath2/klamath2.map&mapext=594411.
> >
>
1981378224+4726172.874518348+602955.0738299278+4732051.
> >
> 173229337&mapsize=610+420&layers=Roads+Shaded_relief
> > 
> > -----------------------------------
> > 
> > Thanks... Any ideas are greatly appreciated!!
> > 
> > Matthew Perry
> > Humboldt State University
> > Natural Resources Planning
> > 
> > _______________________________________________
> > Mapserver-users mailing list
> > Mapserver-users at lists.gis.umn.edu
> >
>
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