Re: curvilinear grid to Set

Hi Jan-Rolf,

I assume you mean dummy values for grid locations.

I can think of two approaches to this:

1. Set the dummy grid locations to Float.NaN (i.e., missing)
and use the Gridded2DSet constructor signature:

  public Gridded2DSet(MathType type, float[][] samples, int lengthX,
           int lengthY, CoordinateSystem coord_sys, Unit[] units,
           ErrorEstimate[] errors, boolean copy, boolean test)

with test = false. This will tell the constructor not to
test for missing (i.e., NaN) locations, and not to test for
topology consistency among locations. Some operations with
such a set will fail (throw an Exception, or fail in some
more silent manner), including possibly some operations
necessary for visualizing the data. But its worth a try,
since if it works in your case, it'll be the easy approach.

2. Construct an Irregular2DSet from only the non-missing
locations. You can either use an Irregular2DSet constructor
without a Delaunay argument and let it invoke a Delaunay
algorithm to derive a tology for your non-missing points, or
you can pass it a DelaunayCustom that you construct to define
the topology among the non-missing points. For this, you might
break each intact grid box (i.e., all four corners are
non-missing) into two triangles, express each grid box with
three non-missing corners as one triangle, and eliminate all
grid locations that are not part of at least one triangle.

Good luck,
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738

On Tue, 15 Apr 2003, Hendriks, Jan-Rolf (HMC) wrote:

> I am trying to produce a Set corresponding to my curvilinear grid. The
> problem is: my curvilinear grid (dimensions m x n) contains dummy values for
> some m,n points (where m and n are just index values for the grid).
> for example:
>   X--X--X
>    \   \
>     X--X
>      \   \
>       X--X
> where the curvilinear grid contains a m x n (3 x 3) grid, the 2 missing
> corresponding x,y value-pairs do have some dummy value.
> Is it possible to use a Gridded2DSet or some work around ?
> Best Regards,
> Jan-Rolf Hendriks
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