-------- Original Message --------
Subject:        Re: MAPS-L: Searching by coordinates questions
Date:   Tue, 17 Jan 2006 11:55:46 -0600
From:   James R. Carter <[log in to unmask]>
To:     Maps, Air Photo & Geospatial Systems Forum <[log in to unmask]>



Relative to questions below about the nature of a search by coordinates, I
have to refer to the paper reference maps by USGS for their geologic
investigations.  Although I have not had to reference these in some years,
I assume they still publish these.

As I remember these maps were by State and showed the outline of the area
of each geologic map.  In some cases the polygons of coverage were very
odd-shaped, as they followed a valley of bit of stratigraphy.  There were
reference numbers so that you could find the source of the original map and
its scale.  If you wanted to know what geological literature existed for
any specific place, you would start with these reference maps.

It seems to me, this is a standard that should be used if you want to
search by coordinates.  If you define your coordinates of coverage based on
the smallest rectangle that encloses the polygon, then in many cases you
will imply availability of map coverage when it does not exist.

Jim Carter, recalling days from my geologic past.

At  1/17/2006, you wrote:
>-------- Original Message --------
>Subject:        Searching by coordinates questions
>Date:   Tue, 17 Jan 2006 10:05:50 -0500
>From:   Jimmie Lundgren <[log in to unmask]>
>To:     Maps, Air Photo & Geospatial Systems Forum <[log in to unmask]>
>
>Dear MAPS-L Subscribers,
>
>        Regarding the MARC Discussion Paper 2006 DP01 on adding
>geographic coordinates to authority records for places, the following
>message was sent to the MARC discussion list by Karen Coyle. I am hoping
>that some of you or your associates will be willing to help address
>these questions. Thanks in advance for any help!
>
>"I would like to see discussion about the use of coordinates for
>searching. This DP says: "Searching by geographic coordinates is offered
>as a mode of access by only a few library catalog systems vendors at
>this time, although it may be offered more frequently in the future."
>The one time that I was involved in an attempt to define a search based
>on coordinates, we ended up not doing it because we couldn't find a
>clear definition of how such a search would work. Would the coordinates
>of a search query have to match the coordinates in the record exactly?
>Would a record be retrieved if query coordinates were within the
>coordinates in the record? Overlapping with the coordinates in the
>record? Would a record be retrieved if the coordinates in the record
>were within the coordinates of the query? Does map scale matter?
>
>So if someone has a query algorithm to offer, I, for one, would be
>interested in seeing it."
>
>Best regards,
>Jimmie
>
>Jimmie Lundgren
>U of Florida
>POB 117007
>Gainesville, FL 32611
>[log in to unmask]
>352-392-0351
>
>
>
>--
>
>.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._
>
>ANGIE COPE
>American Geographical Society Library
>UW Milwaukee
>2311 E. Hartford Avenue
>Milwaukee, Wisconsin 53201
>
>http://www.uwm.edu/Libraries/AGSL/index.html
>Hours: M-F 8:00am-4:30pm
>[log in to unmask]
>(414)229-6282 / (800)558-8993 (US TOLL FREE) / (414)229-3624 (FAX)
>
>.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._

---------------------------------------------------------------------
Dr. James R. "Jim" Carter, Emeritus Professor
Geography-Geology Department
Illinois State University, Normal, IL 61790-4400 USA
                      -- http://www.ilstu.edu/~jrcarter --
tel: (309) 438-2833                                 fax: (309) 438-5310
                               [log in to unmask]
----------------------------------------------------------------------