GPS for old specimens

[Eric or Pat Metzler]

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JOSEPH E. LAFERRIERE wrote:
>
> Contrary to what my distinguished colleague Dr. Humphries said
> yesterday, it is frequently impossible and often misleading to
> attempt to assign precise coordinates to old specimens.

There was a thread about this subject 6 months ago.  Chrissy van Hilst
cvanhils at sivm.si.edu  compiled all responses.  Here is how we tackled
the problem in Ohio.

Good Luck.

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From: Metzler <spruance at infinet.com>  You might want to
consider a scale of relative uncertainty (fuzziness scale) as
described below.  This was also printed in the ACS newsletter a
couple years ago
 Eric H. Metzler
Ohio Biological Survey
614 888 3642
spruance at infinet.com
THE COMPREHENSIVE SURVEY OF OHIO MOTHS AND
BUTTERFLIES
                 completed by The Ohio Lepidopterists

Project No. NGSCW-91-11
Information pertinent to the concept of RELATIVE CERTAINTY

 in the final report to ODNR  30 September 1992

The Ohio Lepidopterists strived to provide detail about the capture
localities of the records in the collective databases.  The detail
included all information from the locality labels associated with
each specimen.  In addition, The Ohio Lepidopterists sought to
provide the latitudinal and longitudinal coordinates for as many of
the collecting localities as possible.  The purpose of this report is to
provide information pertinent the  methods used to calculate those
coordinates.  Two thousand one hundred fourteen discrete
collecting locations were registered for specimens collected in
Ohio.  The exactness of the localities varied from vague, such as
someplace within the state of Ohio, to extremely specific, whereby
the stated location is a few feet.  The center of each location was
used to record the latitude and longitude, but given the unequal size
of the recorded locations, a method was developed to stipulate the
size of the geographical area represented by each locality.  A
SCALE OF RELATIVE CERTAINTY was conceived to
represented the size of the area for each locality. The Scale of
Relative Certainty was designed to reflect the precision of the data
labels.  Since some labels indicate a linear site, i.e. "along highway
82", the Scale of Relative Certainty has two scales, one for square
area, S1, S2, etc., and one for linear sites, L1, L2, etc.  The Scale of
Relative Certainty is printed at the end of the report.  The method
of plotting Latitude and Longitude is straight forward. If the
collector knew the latitude and longitude, those calculations were
used.  For most other sites, county maps as published by the Ohio
Department of Transportation (ODOT) were used.  Occassionally
the ODOT maps were supplanted by 7.5' topographic maps, other
county maps, or other city maps.  The ODOT county maps included
tick marks for latitude and longitude.  In a few cases, i.e. Lake
County and Ottawa County, the tick marks were found to be in
error, thus The Ohio Lepidopterists used topographic maps to
replace the ODOT tick marks with correct coordinates.  The
locations written on the specimen data/locality labels were located
on the county maps, and a rule was used to calculate the latitude
and longitude to degrees, minutes, and tenths of minutes. For
locations that indicated an area, i.e. Vinton County, Brown
Township, Section 11, the center of the area was used as the
precise spot for the latitude and longitude.  For linear sites, the
exact center of the linear site was used to  calculate the latitude and
longitude.  The Scale of Relative Certainty was employed to
determine the correct uncertainty code.  The uncertainty codes
were applied starting from largest area to smallest area.  Localities
were not made to fit into the most precise code.  For example, the
square area of the City of Columbus is larger than a township but
smaller than a county.  Rather than make the square area of the City
of Columbus more precise than stated on the label, the code for
county, S7, was used.  Given the diversity of habitats in an area the
size of  Columbus, accuracy greater than what is stated on the data
label creates precision that is unwarranted.  As the sizes of the
localities get larger, useful detail about the habitat requirements of
the species are lost.  Future researchers can use the database to
access the specimen if they need to know more about the sample.
The codes of relative certainty were recorded in the database in
degrees, minutes, and tenths of minutes.  The computer used these
data to calculate the coordinates in degrees, tenths, hundredths, and
thousandths of degrees.

The Scale of Relative Certainty follows:

SCALE OF RELATIVE CERTAINTY

September 28, 1992

CODE DEFINITION
S1        Precise location, plus or minus 200 ', is known.
S2        Location is known to be within a circle 1/4 mile in
            diameter.
 S3       Location is known to be within a circle 1/2 mile in
            diameter.
 S4        Location is known to be within a Section or
                 equivalent.
 S5        Location is known to be within a circle 2 miles in
             diameter.
S6        Location is known within one township (about 36 sq.
             miles) or equivalent.
S7        Location is known to be within a County.
S8        Location is known to be within 1/2 of the State of
            Ohio.
S9        Location is known to be within the State of Ohio.

 L1       The linear site is known to be no more than 1/2 mile
            long.
L2        The linear site is known to be no more than 1 mile
             long.
L3        The linear site is known to be no more than 2 miles
             long.
L4        The linear site is known to be no more than 6 miles
            long.
L5        The linear site is known to be no more than 36 miles
            long.
 L6        The linear site does not exceed a distance equal to
           1/2 of the State of Ohio.
 L7        The linear site does not exceed a distance equal to
             the diameter of the State of Ohio.
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