Geographically square pixels

[Ed McNierney]

Peter -

If you have an image in that projection, the scale MUST be expressed in "degrees".  That's not a very useful value because a degree of latitude isn't the same size as a degree of longitude, and "one degree" measured at an angle isn't a very useful measurement to most people.  However, that's the property of the map projection you're using, and that's what the scale will be.

If you need to provide the ability to measure distances in feet or meters or the like, you will need to construct a JavaScript measurement tool or similar doodad to do the calculation.  The USGS does something like this on the National Map viewer site.

        - 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

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On Behalf Of pw
Sent: Wednesday, November 10, 2004 1:08 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Geographically square pixels

Hello,

In my configuration file (.map file)  if  I have an image that is projected with equal area degrees pixels,
(ie: each pixel is evenly sized in 'seconds' not feet or meters) how can I set up mapserver to know what scale the pixels are in the X and Y direction for the raster?

I have been looking at the proj4 manual and at the mapserver manual and there doesn't apper to be any way to define the extents of an input raster in degrees so that it can be mapped to, say, lambert.

Thanks for any insight,

Peter