[mapserver-users] projection confusion

[Ed McNierney]

Matt -

There isn't any "look right" here - the expected shape of these polygons
is completely dependent upon the projection chosen.  Since you're
talking about "buildings", I'm assuming that they are pretty small
polygons (in a global sense) and therefore won't be affected as much by
the projection, except in their orientation.  That is, the difference
between UTM and decimal degrees will be a shape that's about the same
but rotated (roughly).

If your buildings are being projected into nowhere, check the EXTENTS
parameter in the map file.  If you're not defining a projection, you'll
need to be sure that the range of coordinates in your shapes lies within
the extents of the map.  If your coordinates are in decimal degrees,
then your extents need to be in decimal degrees, too.

If you can post the map file and/or the shape file data it would be
helpful if you're still stuck.

	- Ed

Ed McNierney
Chief Mapmaker
TopoZone.com
ed at topozone.com
(978) 251-4242


-----Original Message-----
From: Matt Carlson [mailto:matt at aruke.com]
Sent: Thursday, September 20, 2001 3:55 AM
To: mapserver-users
Subject: [mapserver-users] projection confusion


version : 3.3.011
built with proj : 4.4.3

hi,  we are dealing with a client right now that is saying that the
building
polys being served up by mapserver look 'crooked'.  is this a projection
issue?  the files are using dd for units, do these need to be projected
a
certain way to look right?  i tried playing with some different
projections
in my map file and always came up with a white map.  i'm suspecting my
map
is being projected out into nowhere.  when the data was originally made
it
was projected from meters to wgs84 dd.  do i need to define a projection
in
mapserver in order for these buildings to come out right?  is this
something
that can be defined in the map file?

thnks for any help, i'm a programmer not a gis guy basically lost here.

matt