[mapserver-users] New User - Projection Question

[Pericles S. Nacionales]

Hi there.  I don't use Proj.4 myself so I can't help you directly.  However,
I can give you a little advice.

First you need to know what projection these datasets are in.  If they have
different projections then you might want to standardize.  For the
Continental US, the common projection systems are Lambert Azimuthal
Equal-Area, and Albers.  From what you're saying, it sounds like your
datasets are unprojected--in geographic coordinates.  You can certainly use
PROJ.4 and reproject on-the-fly in MapServer.  However, I'd recommend you
reproject your datasets to one of the projections mentioned above.  In
either case, here's the standard Continental US parameters for Lambert
Azimuthal Equal-Area projection:

 Ellipsoid (Spheriod): Clarke 1866
 Central Meridian: -100 (100 degrees West)
 Reference Latitude: 45
 Units: Meters

And here's the parameters for Albers Equal-Area Conic:

 Ellipsoid/Spheroid: Clarke 1866
 Central Meridian: -96
 Ref Latitude: 37.5
 Standard Parallel 1: 29.5
 Standard Parallel 2: 45.5
 False Easting: 0
 False Northing: 0

If you want to use PROJ.4, look at the PROJ.4 documentation for proper
syntax use.  Also, look at the MapServer docs at
http://mapserver.gis.umn.edu/coordinates.html.

Good luck!

-Perry




-----Original Message-----
From: owner-mapserver-users at lists [mailto:owner-mapserver-users at lists]On
Behalf Of Mike Boone
Sent: Friday, July 13, 2001 6:07 PM
To: mapserver-users at lists
Subject: [mapserver-users] New User - Projection Question


Hi all.

I'm a novice user who stumbled upon mapserver as a way to plot GPS tracks on
the web.

I was looking at examples of mapserver in use and found this one:
http://www.sis.ec.gc.ca/msapps/ec_species/htdocs/ec_species_e.phtml

What makes this different from what I've done is that this map's longitude
lines look like they will merge at the north pole. I think this was done by
some projection change, but maybe that layout is stored in the shapefile?

I swiped a 50 states shapefile from nationalatlas.gov and it displays in my
mapserver in a "flat" layout. How can I get it to map-out like the Canada
map in the example?

I have PROJ.4 compiled into my mapserver OK, but I after putting various
PROJECTION settings in my mapfile, I see no difference.

Is PROJECTION the right place to get this result, or do I need shapefiles
made specifically for this purpose?

Please excuse me if my terminology is wrong...I'm still figuring it all out.

Thanks!
Mike Boone
mike at boonedocks.net