Yilmaz Arslanoglu wrote:
you need to be clear by what you mean here: I suspect you mean:
"The shortest distance between two points following the surface of the
earth"
Yes Chris, you are right. Actually my purpose is to make a bathymetric
prediction of a given position, with the help of the contours and sounding
points at hand. I just thought that it would be a better idea to take shortest
distances in calculations (maybe the Kriging) rather than using pure lat-lon
values. So does it make sense to use the geodesic distances for the
closeness criteria?
I don't think so -- at that scale, it really won't make much difference
-- probably far less than the accuracy you need, so I don't think it's
worth the computational overhead.
If you want to do a little better than simple lat-long, do the
calculations in projected coordinates, using a appropriate projection.
Do be careful about Kriging -- Kriging assumes a certain smoothness to
the data -- it won't capture cliffs well. though no matter how you slice
it, if you don't have a sounding there, you're not going to get it perfect.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
[email protected]
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