Which Projection to use?

[Fawcett, David]

Nelson, 

I assume that you are trying to use MapServer as a WMS or WFS server.
If you haven't seen this HowTo, check it out:
http://mapserver.gis.umn.edu/docs/howto/wms_server  It gives you an
example map file and tells you what metadata is required.

Part of serving a WMS/WFS is that people who want to use your data
service need to know what projection it is in.  To do this, they send a
GetCapabilities request and are returned a document that describes your
service.  Projection information is needed for the GetCapabilities.  

The first step is to determine/understand what spatial reference system
(projection) your data is in.  Once you know that, you can add
projection blocks to your map file.  For your situation, it sounds like
the input projection for your data is the same as the output projection
of your map.  In other words, you are keeping it in the same projection.
In this case, you just need to put the same projection blocks at in the
MAP object and the LAYER object of your map file.  

If your data was in UTM Zone15, NAD83, you could use a block like this:

PROJECTION
   "init=epsg:26915"
END    

David.

-----Original Message-----
From: LITTLE Nelson [mailto:nelson.little at tenix.com] 
Sent: Monday, September 17, 2007 10:27 PM
To: Fawcett, David; MAPSERVER-USERS at lists.umn.edu
Subject: RE: [UMN_MAPSERVER-USERS] Which Projection to use?


David,

Thanks for your reply. What PROJECTION info do I specify and what values
do I give that data? 

I see in the mapfile reference page the examples either reference a
projection from the epsg file (which one would I use?) or supply the
values for proj, ellps, datum. 

I don't want my x-y data to be projected any differently to how it is
presented in the map files.

Cheers,
Nelson

-----Original Message-----
From: Fawcett, David [mailto:David.Fawcett at state.mn.us] 
Sent: Monday, 17 September 2007 11:37 PM
To: LITTLE Nelson; MAPSERVER-USERS at lists.umn.edu
Subject: RE: [UMN_MAPSERVER-USERS] Which Projection to use?

If all of your data is in the same projection, you don't need to define
projections in your map file.  

One exception is that if you are serving the data up as a WMS or WFS,
you will need to define MAP and LAYER level projections.  You will
likely also need to add metadata at the LAYER and MAP? level that
includes information about the projection.  

David.

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of LITTLE Nelson
Sent: Monday, September 17, 2007 1:42 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Which Projection to use?


Hi all,

I have shape files which are in x,y coordinate form (units of meters)
and didn't think I needed any projection information because I was
dealing with such a small area, thus never defined any PROJECTION info
in my map file. Now I am getting the following error: 

[MapServer Error]: _msProcessAutoProjection(): WMS/WFS AUTO PROJECTION
must be in the format 'AUTO:proj_id,units_id,lon0,lat0' (got '').

I gather from the error message that I need to define at least a map
level projection entry, but I am not sure what I should use?

Any help much appreciated

Cheers,
Nelson

Disclaimer :
The contents of this e-mail including any attachments are intended only
for the person or entity to which this e-mail is addressed.  If you are
not, or believe you may not be, the intended recipient, please advise
the sender immediately by return e-mail, delete this e-mail and destroy
any copies. Tenix does not warrant nor guarantee that this email
communication is free from errors, virus, interception or interference.

Disclaimer :
The contents of this e-mail including any attachments are intended only
for the person or entity to which this e-mail is addressed.  If you are
not, or believe you may not be, the intended recipient, please advise
the sender immediately by return e-mail, delete this e-mail and destroy
any copies. Tenix does not warrant nor guarantee that this email
communication is free from errors, virus, interception or interference.