-------- Original Message --------
Subject:        RE: Simple? Cataloging Questions
Date:   Wed, 9 Sep 2009 14:12:11 -0400
From:   Grabach, Kenneth A. Mr. <[log in to unmask]>
To:     [log in to unmask] <[log in to unmask]>
References:     <[log in to unmask]>



Paige put it really well.  I want to add a bit, partly to make sure I am understanding what you are really trying to ask.  The coordinates as given in 255 $c should be thought of as the corners of a quadrangle.  First are the West-East boundaries or corners.  If you have a map that straddles the Prime Meridian, say a map of Britain, of France, North Africa, etc., the western coordinate would be rendered as W, and the Eastern as E.  If the meridian is one of the bounding longitudes, you would render it depending on which hemisphere the map is actually in.  Where the Greenwich meridian as to the eastern edge, the map is showing something in the Western hemisphere, so you would use W.  If the meridian is at the western edge, the map is showing the Eastern hemisphere, and the longitude would be rendered as E.

The same holds for the Equator, and the North-South boundaries or corners.  If the map straddles the Equator, you would use both N and S for the coordinates of the map.  If the map shows the Equator as at the southern edge, the map is in the Northern hemisphere, and you would use N.  Conversely, if the map is in the Southern hemisphere, with the Equator at the northern edge, you would use S.

Cartographic Materials gives further explanation of this, in 3D.  It also tells how to render coordinates for world maps.  But again, how to render the Prime Meridian or the Equator only enter into it when one or both is a bounding coordinate.  You are really telling the user what hemispheres the map portrays a view of:  East or West, or both, and North or South, or both.

Ken Grabach                           <[log in to unmask]>
Maps Librarian                          Phone: 513-529-1726
Miami University Libraries
Oxford, Ohio  45056  USA


-----Original Message-----
From: Maps, Air Photo & Geospatial Systems Forum [mailto:[log in to unmask]] On Behalf Of Maps-L Moderator
Sent: Wednesday, September 09, 2009 1:51 PM
To: [log in to unmask]
Subject: Re: Simple? Cataloging Questions

-------- Original Message --------
Subject:        Re: Simple? Cataloging Questions
Date:   Wed, 09 Sep 2009 13:51:03 -0400
From:   Paige Andrew <[log in to unmask]>
To:     [log in to unmask], [log in to unmask]
References:     <[log in to unmask]>



Kathy,

You are mixing up your projection statement with your coordinates
values. No directional information goes with projection information,
only the name of the projection as it appears on the map goes into
255$b. Coordinates go into 255$c and must include directional
information. Although not necessarily "politically correct" I think
the direction for Greenwich prime meridian has traditionally been "W
0[degrees]"

Paige

At 01:37 PM 9/9/2009, Maps-L Moderator wrote:
>-------- Original Message --------
>Subject:        Simple? Cataloging Questions
>Date:   Wed, 9 Sep 2009 10:08:08 -0700 (PDT)
>From:   Kathleen Stroud <[log in to unmask]>
>To:     Air Photo Maps-L <[log in to unmask]>
>CC:     Dawn Collings <[log in to unmask]>
>
>
>
>In the Statement of Projection (field 255 $c) What is the direction
>(E or W?)for the Prime Meridian,  0 degrees? Do we have to fill in
>the direction blank?
>
>Thanks,
>
>Kathy Stroud, Map/GIS Librarian
>Biological/Agricultural Sciences and Map Services, Shields Library
>100 NW Quad Ave.
>Davis, CA 95616-5292
>530-752-5248