geographic data

David Barr dbarr at EPAS.UTORONTO.CA
Sat Aug 6 05:59:24 CDT 1994

RE: Jack Longino's issues for a survey database.

Assuming I understand the question, the Costa Rican arthropod
survey database would use the 'locality' table for an entry like
Puerto Limon or Vesta.  Then the collection table would be linked
to the Vesta locality for all collections that were closer to Vesta
than to Puerto Limon (or any other entry in the locality table).
If this is correct, then I agree that lat/long and elevation are
better as attributes of a collection than of a locality record.

In mountainous terrain of course, collections very close to the
same 'locality' can have radically different elevations with
significant faunal/floral effects.

It's equally important to have exact latitude and longitude of a
collection site (site of the population sampled) for biogeographic
analyses - e.g., contouring, interpolation (kriging), correcting
for the effects of spatial autocorrelation, etc.  Getting accurate
data for individual collecting sites is unusually easy now with the
general availability of GPS (satellite global positioning systems).

One addition to the sources of latitude and longitude data - GIS &
related mapping programs now enable one to capture coordinates from
the cursor position on a map shown on the computer screen.  Not as
accurate as GPS, but better than nothing if no published gazeteers
are available and for those annoying sites far away from any listed
gazeteer locality.

One can find loads of news and views on GIS - geographic information
systems (including interfacing with various forms of satellite data)
on GIS-L at (the usual listserver conventions apply).

Dave Barr, Royal Ontario Museum, Canada
(416)586-8094  FAX:(416)586-5863  Email:davidb at

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