Catching lat lon in wrong country errors

[Steve Ginzbarg]

Mary Barkworth brought up the problem of how to catch errors where
the lat lon for a specimen doesn't fall within the country where it
was said to have been collected.

The Alexandria Digital Library has fields w_b_coord, e_b_coord,
n_b_coord, and s_b_coord. ADL Catalog records give

titles:
Alabama
geographic-locations:
Lat/Lon Bounding Box: North=35.07 South=29.76 East=-84.87 West=-88.5

Is anyone who is using ADL as their geographic authority file making use
of the bounding boxes of countries and their political subdivisions
to check if a lat lon for a specimen actually falls within a
rectangle containing the country and political subdivisions it is
reported for?

The Getty Thesaurus of Geographic Names
http://www.getty.edu/research/conducting_research/vocabularies/tgn/ind
ex.html gives only the centroid and not a bounding box.

MicroCam for Windows by Scott A. Loomer, loomer at att.net, has the
latitude and longitude of each point in the polygon forming the
border of a country or political subdivision. One could calculate the
area's bounding box by finding the maximum and minimum latitude and
longitude of all the points forming the border. Is there a way to
determine whether a latitude and longitude from a specimen is within
the "fill" area of the polygon?

Does anyone know of other geographic authority files that include
bounding boxes for political subdivisions?

The following response is from the HERBARIA list:

From:   "Mary Barkworth" <Mary at biology.usu.edu>
        To:     <herbaria at scarab.science.oregonstate.edu>
        Subject:        [HERBARIA] Map problems
        Date sent:      Mon, 20 Dec 2004 16:03:30 -0700

Further to my question/comments about lat lon errors in our database
(and the majority are correct, despite my phrasing in the message that
triggered Steve's comment:
The following from Russell, the student to whom I sent the email that
started the thread:

Steve asked:  Is there a way to determine whether a latitude and
longitude from a specimen is within the "fill" area of the polygon?
Yes, it's called the point-in-polygon algorithm.  Depending on how
accessible the data in Microcam turn out to be, I'm looking forward to
implementing it.  It's quite exciting to think that something I learned
in a CS class will actually be put to use in the `real' world!
Once we get it working, it won't be hard at all to stitch it into a
lat/lon data entry form, so we will be able to flag all the current
errors as well as prevent some future headaches.

Hmm.  Herbaria are part of the real world? What a lovely thought!

Mary

_______________________________________________
HERBARIA mailing list
HERBARIA at scarab.science.oregonstate.edu
http://scarab.science.oregonstate.edu/mailman/listinfo/herbaria

-Steve Ginzbarg

Steve Ginzbarg, Assistant Curator
Herbarium (UNA)
Department of Biological Sciences
Box 870345
The University of Alabama
Tuscaloosa, AL 35487-0345

(205) 348-1829, FAX: (205) 348-6460
sginzbar at bsc.as.ua.edu