[mapserver-users] mapfile projection

Andy Colson andy at squeakycode.net
Tue Jul 14 13:27:21 EDT 2009


Hi all,

I'm working on my first mapping project, so IANAM (I am no a mapper). 
Here is the projection info from a shapefile I'm using:

PROJCS["NAD_1983_StatePlane_Iowa_North_FIPS_1401_Feet",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",4921250.0],
PARAMETER["False_Northing",3280833.333333333],
PARAMETER["Central_Meridian",-93.5],
PARAMETER["Standard_Parallel_1",42.06666666666667],
PARAMETER["Standard_Parallel_2",43.26666666666667],
PARAMETER["Latitude_Of_Origin",41.5],
UNIT["Foot_US",0.30480060960121924],
PARAMETER["scale_factor",1.0]]

I used QGIS to create a mapfile, and it generated this:

PROJECTION
   'proj=longlat'
   'ellps=WGS84'
   'datum=WGS84'
   'no_defs'
   ''
END

I was kind of thinking this (Thanks to FrankW for helping me find the 
right epsg code):

PROJECTION
  'init=epsg:3417'
END


Is the first one even right?  Would there be a difference?  Why might I 
choose one over the other?  I'm going to put this into postgis, with 
srid = 3417, will that make any difference.  (I'd like to avoid 
re-projections.. I think... don't I?)

-Andy



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