Georeferencing

[Stuart G. Poss]

With regards to the Robin P. and Julian H. dialog, an important point
needs to be reemphasized, namely that locality data (including
georeferencing) made at the time of collection should in some way be
differentiated from locality data (including but especially
georeferencing) added subsequent to the collection event.

        As noted by many, addition of subsequent data has the potential to
either be misleading or worse result in providing inaccurate
information, often inadvertently.  If one adds data subsequently, the
potential exists to characterize a locality different from that
originally collected.  It is information independent from that
associated with the original collecting event.

        Adding precision that is not inherent in the original data is only one
aspect of this problem, but it is an especially important because of the
wide use of coordinate data for GIS, with or without a measure of
accuracy.  The practice of using information models that do not
distinguish between locality fields, such as lat/long, do not permit the
user to distinguish between information taken at the time of collection
from that added subsequently are especially troubling, since the
confidence one can place in the data from such collections is lessened,
the accuracy of subsequent georeferencing aside.

        For those such as myself, who are attempting to use collections data to
assess historical changes in distributional patterns, it is potentially
a disaster; because one may no longer be able to determine what the
original data associated with the collecting event was.  I would
certainly hope that collections failing to use distinct fields or
protocols to distinguish such data would inform users that their data
are suspect.  Collections that have failed to make the distinction and
have also discarded their original non-electronic files and labels may
now be well on their way to becoming worthless as historical archives.


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Stuart G. Poss                       E-mail: sgposs at whale.st.usm.edu
Senior Ichthyologist & Curator       Tel: (601)872-4238
Gulf Coast Research Laboratory       FAX: (601)872-4204
P.O. Box 7000
Ocean Springs, MS  39566-7000
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