Hi to anyone, this is Michael
>
> > Now the problem is mapping. Luckily, I have a good sense of
> > orientation in the field plus photographic memory, being able to return
> > directly to CP sites visited years before. But it is simply impossible to
> > explain to anyone how to arrive at many of these sites! I try and include
> > as much location data as possible along with the herbaria I collect, but
> > that is unfortunately often far from precise.
>
> For your extensive and ongoing field work, I think you should seriously
> consider getting a hand-held GPS receiver.
>
> These have now gotten down below $300 USD in price and will give you a
> Lat/Long fix within about 100 meters. This allows precise renavigation
> to the site, and provides data that can be precisely overlayed on topo
> maps or satellite images. In most industrialized countries, differential
> GPS is available with resolution to 1m or so.
(differential GPS is significantly more expensive and works only in a
limited distance to your beacon station. However, there are some slight
hopes that your DoD will give up the "selective availability" feature
which will increase lat/long fixes to about 10m accuracy. And last not
least GLONASS the russian alternative to GPS comes without SA.)
I am using such a gadget for hiking and it is really fascinating. Yes,
a compass and a map works fine most of the time (e.g. the map is good,
there are visible landmarks, i.e. no fog/snow, no disturbances in the
earth's magnetic field) but a GPS receiver and hands full of bateries
provide a psychological backbone.
However, you do not need to have a GPS receiver in order to provide
precise information about locations.
Topographic maps exists for many places and locations can be given in
UTM grid coordinates or lat/lon. With a target precision of perhaps
200m you do not even need to bother what geoid your grid is based on.
(as long as it is not something very exotic).
Anyhow, travelling in areas where precise maps are not available it
might be better nowadays to take a GPS receiver with you as a safety
precaution and as a tool to do "scientific work".
..Michael
> The last integrated circuit technical conference I attended had a paper
> describing a chip for a *wrist-watch* GPS receiver!
> Rick
-- Michael Hasemann | Technical Research Centre of Finland - Automation | Kaitovayla 1, P.O. Box 13023, 90571 Oulu, Finland jmh@tko.vtt.fi | Fax: +358 81 5512320 Tel: +358 81 5512239