[ka-Map-users] Re: equidistant projection assumption

[Moran Ben-David]

Ricardo,

I suggest you do what mapbuilder developers had to do...

Which is to rip open proj4 (http://proj.maptools.org/) and lookup the
projection calculation you are looking for in there.

The file you want should have look like PJ_<your projection>.c.  Keep in
mind that inside that file, the coordinates are all in radians and not
decimal degrees.

moran

> -----Original Message-----
> From: ka-map-users-bounces at lists.maptools.org [mailto:ka-map-users-
> bounces at lists.maptools.org] On Behalf Of Ricardo Stuven
> Sent: Thursday, February 16, 2006 10:10 AM
> To: ka-map-users at lists.maptools.org
> Subject: [ka-Map-users] Re: equidistant projection assumption
> 
> I'm trying to load a WMS layer using the DEMIS service which only
> accepts EPSG:4326 coordinates. So I need to convert from ka-map's
> cylindrical equidistant coordinates to geodetic decimal degrees. I've
> checked out mapbuilder library and I found it doesn't implement this
> conversion. But I've found this reference:
> http://chukchi.colorado.edu/GDSIECE/
> 
> lat = ((-y + center_y) / height) * 180
> lon = ((x - center_x) / width) * 360
> 
> ...and others that just say:
> lat = y * 180 / PI
> lon = x * 180 / PI
> (radians to degrees)
> 
> Please, can someone guide me on how to manage ka-map to deal with
> this? For example, telling me the values height and width should have
> or whether should I assume center is (0, 0). Thank you.
> 
> Regards,
> Ricardo Stuven.
> 
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