Help to Re-Project Map Layers on the Fly

[Dan Barron]

Ed,

With one minor change (lon_0=110) this worked perfectly.  I'm a newbie at
projections, have always just used the shapefiles I had without any
problems.  Is there a good tutorial out there for understanding how to work
through projections and determine things like, say the datum if not
specified explicitly?

While looking for a good reference for projection definitions and
abbreviations (e.g. Clarke-1866 = clrk66) I came across these pages:

http://www.safe.com/support/online_help/coordinate-system/coordinate_system_help.htm#predefined_ellipsoids.htm

Is there some better/other resource out there that could be useful?

Thanks again!

Dan


At 12:13 PM 2/2/2005, Ed McNierney wrote:
>Dan -
>
>PROJECTION
>     proj=lcc
>     lat_1=70.0
>     lat_2=50.0
>     lat_0=0.0
>     lon_0=-110.0
>     x_0=0.0
>     y_0=0.0
>     ellps=clrk66
>     datum=NAD27
>END
>
>looks about right.  Remember that you will need PROJECTION blocks for the
>OTHER layers and for the top-level map file to accurately describe the
>other inputs (if any) and the map image output projections as being lat/lon.
>
>      - Ed
>
>Ed McNierney
>President and Chief Mapmaker
>TopoZone.com / Maps a la carte, Inc.
>73 Princeton Street, Suite 305
>North Chelmsford, MA  01863
>ed at topozone.com
>(978) 251-4242
>
>
>----------
>From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
>Behalf Of Dan Barron
>Sent: Wednesday, February 02, 2005 2:37 PM
>To: MAPSERVER-USERS at LISTS.UMN.EDU
>Subject: [UMN_MAPSERVER-USERS] Help to Re-Project Map Layers on the Fly
>
>Hello,
>
>I am looking for a little help to re-project a map layer to LAT/LON for a
>single layer.  Below is the <shapefile>.prj file - how do I define this
>projection in the layer object of the map file?
>
>
>PROJCS["unnamed",
>GEOGCS["unnamed",DATUM["D_unnamed",SPHEROID["Clarke-1866",6378206.4,294.978698213901]],
>PRIMEM["Greenwich",0],
>UNIT["degree",0.0174532925199433]],
>PROJECTION["Lambert_Conformal_Conic"],
>PARAMETER["standard_parallel_1",70],
>PARAMETER["standard_parallel_2",50],
>PARAMETER["latitude_of_origin",0],
>PARAMETER["central_meridian",110],
>PARAMETER["false_easting",0],
>PARAMETER["false_northing",0],
>UNIT["METER",1]]
>
>
>Thanks,
>
>Dan Barron
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