Jon,
I've work with bathymetry data allot. I used to work, in my younger days,
for the U.S. Naval Oceanographic Office. The problem lies with the gradient
change near the shallows and the coast relative to deeper areas. You'll
notice that shallows are either undershot or overshot also along with the
beach areas. This has to do with the changing gradient in these areas. The
beast approach that I've come up with is to grid these areas separately and
then merge them into your over all grid.
Doug Wilson
Emcon, Environmental Management and Consulting
Anchorage, Alaska
> -----Original Message-----
> From: Jon Rees EG CEFAS [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, May 11, 1999 4:30 AM
> To: 'mapinfo-l'
> Subject: MI Contouring Bathymetry
>
> Hi,
>
> After lurking for awhile I've a question for all you MI power users ...
>
> I've got a rather nice data set of the depths of the Irish Sea on a very
> fine mesh and wish to create contours of various depths. The depths are
> positive (we Oceanographers view the world the other way around !!!) with
> dry land as -99.
>
> I've used vertical mapper and produced some very good contours. However,
> if you look closely the values near the coast are higher than they should
> be (the gridder trying to take account of the -99).
>
> I've tried various other options e.g. set the land to zero, blanking out
> the land using coast regions but to no prevail.
>
> Any suggestions ???
>
> Thanks
>
> Jon Rees
> CEFAS, Lowestoft
> Email: [EMAIL PROTECTED]
> http://www.cefas.co.uk
> Tel: +44 (0)1502 524383
> Fax: +44 (0)1502 513865
>
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