[Taxacom] Inappropriate accuracy of locality data
kmagnacca at wesleyan.edu
Tue Nov 30 14:12:31 CST 2010
On Mon, November 29, 2010 11:28 am, Tom Schweich wrote:
> Always keep the datum with the original collection data. In my
> case, it's WGS 1984. In North America, some like to use NAD 1983.
> They're both good systems. At Mono Lake, though, the same
> coordinates in WGS 1984 and NAD 1983 are 86 meters apart. If the
> location is simply "Mono Lake," then it's no big deal. However,
> if the location is the highly faulted terrain south of the lake,
> the 86 meter difference could easily put you in the wrong drainage.
If you have an 86m difference in the US, you're doing something
wrong. WGS84 is essentially NAD83 extended to the entire world.
Even here in Hawaii there is essentially no difference between them.
My personal gripe is that most GPS units don't record any kind of
accuracy information when they take a point. I also use a Garmin
76csx and it is capable of recording points to 3-5m accuracy even
under forest cover, but not every point is like that; and to keep
track of accuracy means having to write it down in a notebook and
add it in later.
University of Hawaii-Hilo
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