[Mapserver-users] Projection help

[Eric Bridger]

Kieran,

I know little about projections, but recently got a UTM layer to display
on my non-projected map. So here's what I found:
1) make sure mapserver was compiled with PROJ4 support: /cgi-bin/mapserv
-v will tell you.
2) Create an overall map projection in the map file, near the top:
PROJECTION
 "proj=latlong"
END
3) Create a utm projection for the UTM layer:
LAYER
  PROJECTION
    "proj=utm"
    "ellps=GRS80"
    "zone=19"
    "north"
    "no_defs"
  END
 ...
4) The other layers need no PROJECTION, will default to latlong
5) shpinfo.pl -file="your_utm_shapefile" will report the EXTENT in
meters of the UTM layer. I started with a map file just to get the UTM
shapes alone to display.
6) Caveates:  Maine and Mass are in UTM zone 19. Virginia is in zone 18:
see:
http://www.colorado.edu/geography/gcraft/notes/coordsys/gif/utmzones.gif
My UTM data was NAD83 not NAD27.  Not sure how much difference this
makes.

HTH
Eric Bridger


On Wed, 2003-02-26 at 12:44, Kieran J. Ames wrote:
> List,
> I've never had to project data (until now) and would like to ask for
> some help in trying this out.
> All my data are either internally created or derived from ArcView
> StreetMaps.
> The only information I include in my map file are the UNITS DD statement
> at the top and the scalebar's UNITS MILES statements. I have no other
> projection information included.
> I'd like to include the Fish and Wildlife Service's wetlands polygons,
> but they are projected in UTM, NAD 27, meters.
> Could someone tell me how I could include these layers to match up to my
> decimal degree data? I'd want to include wetlands (coastal waters) from
> Maine to Virginia.
> 
> Sample working map file layer definitions follow.
> 
> Thanks,
> Kieran
> 
> LAYER
>   NAME "Background"
>   TYPE Polygon
>   STATUS DEFAULT
>   DATA 'National/Backgrnd'
>       CLASS
>         COLOR 162 202 240 # OCEAN BLUE
>      END  # CLASS
> END  # LAYER
> 
> LAYER
>   NAME "North-America"
>   TYPE Polygon
>   MINSCALE 18000000
>   STATUS DEFAULT
>   DATA 'National/North-America'
>       CLASS
>         Name 'North-America'
>         COLOR 109 185 14
>         OUTLINECOLOR 0 0 0
>      END  # CLASS
> END  # LAYER
> 
> 
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