p.s., Re: anyone plotting coastlines?

• To: jfmoses@xxxxxxxxxxxxxxxxxxxx
• Subject: p.s., Re: anyone plotting coastlines?
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Tue, 28 Mar 2000 11:03:46 -0600

> > Also, i've got a set of Quikscat wind speeds at irregular points in a
> > scalar and am about to write an objective analysis class to fill in the
> > holes so i can isocontour.  i see hints of grid interpolation methods but
> > still find it hard to understand how to implement (i'm not that familiar
> > with how the pieces fit together) - so find myself resorting to custom code
> > to keep my spirits up.  suggestions welcome here too!
>
> The easiest way to do this is to put your wind speeds into a
> FlatField whose domain Set is an Irregular2DSet that defines
> the locations of the wind speeds.  If you map the domain
> RealTypes to spatial DisplayRealTypes and map wind speed to
> Display.IsoContour, then the VisAD display logic will render
> contour lines based on the irregular topology.  This will
> allow you to skip the explicit objective analysis (which would
> of course interpolate your wind speeds to a Gridded2DSet).

I should point out that the current VisAD algorithm for
contour lines of irregular data does not produce labels.
To get labels, you can construct a 'FlatField winds' of
your wind speeds with an Irregular2DSet for its domain
Set, then construct a 'Linear2DSet gridded_set' that
covers the region of your Irregular2DSet, then do:

  FlatField gridded_winds = (FlatField)
    winds.resample(gridded_set, Data.NEAREST_NEIGHBOR, Data.NO_ERRORS);

Now gridded_winds has the wind speed interpolated to a
regular grid, and if you link it to a DisplayImpl you can
get contour lines with labels.

Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html