"Curtis Olson" wrote:
> On Wed, Jan 14, 2009 at 12:23 PM, Martin Spott <martin.sp...@mgras.net>wrote:
> > BUT, the story about merging vector data is still not right on topic.
> > Your response lacks an explanation why you consider it as being
> > impractical to blend the bathymetry data against the coastline in the
> > same manner as we're currently dealing with the SRTM elevation grid.
> (1) SRTM data has +/- 5 to 10 meter error built in. In land regions with a
> very flat slope leading up to the coastline that can lead to things like
> hundreds of meters of coast line inaccuracy, or very odd artifacts and very
> unnatural boundaries. How about the Dead Sea or Death Valley?
>
> (2) I think it will be very easy for entire regions to get put under water
> if there are small errors in terrain elevation or small errors in tide
> computation.
To my understanding of your posting you're implying that someone would
like to move the shoreline around. Indeed, if we would derive the
coastline entirely from the SRTM elevation, then we theoretically
_might_ run into trouble, but nobody's talking about such a plan.
BTW, the sort of bathymetry data I'm talking about has, per definition,
always an 'elevation' at or below zero MSL, therefore, as long as we
neither move the coastline (or simulate global warming ;-) , there's
no risk of putting KSFO under water, simply because it's above sea
level and inside the coastline.
Cheers,
Martin.
--
Unix _IS_ user friendly - it's just selective about who its friends are !
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