Re: filling a 'coastline' ??

• To: Stuart Maclean <stuart@xxxxxxxxxxxxxxxxxx>
• Subject: Re: filling a 'coastline' ??
• From: Bill Hibbard <bh@xxxxxxxxxxxxx>
• Date: Thu, 25 Jan 2007 18:32:58 -0600 (CST)

Hi Stuart,

I'd like to try to 'fill' the coastline data derived from e.g. OUTLUSAM using the mcidas BaseMapAdapter. Using the Rivers.java approach, I can get the coastline drawn as lines, but not as filled polygons. I should point out that I am not entirely certain that the data in OUTLUSAM is actually all closed polygons.

The fill() method was written at the request of the
Australian BOM for the purpose of filling coastlines
and other geographical boundaries, and does that
successfully.

I did see on the list how DelaunayCustom.Fill might be useful. However, I got an exception

visad.VisADException: path self intersects
       at visad.DelaunayCustom.fillCheck(DelaunayCustom.java:499)
       at visad.DelaunayCustom.fillCheck(DelaunayCustom.java:451)

which may or may not have been specific to my data.

Boundaries from a file like OUTLUSAM are likely to
have all sorts of self intersecting cases. One of
the main problems is boundaries whose first and last
points are identical. Leave off the last point and
let the fill() method implicitly close the polygon.

My bigger concern is that i am using a display side coordinate system and Map Projections from ucar.unidata.geoloc, much like the IDV does. It seems to me that I cannot do the fill in lat/lon, I would need to fill in x,y, or am I being very stupid?

A display side CS should not be a problem since the
fill() method is just converting one Data object to
another (i.e., working on the data side before any
display logic is invoked). Its easiest to use the
fill() signature whose argument is a Gridded2DSet
with manifold dimension = 1 and which returns an
Irregular2DSet. These Sets are then both in lat/lon
coordinates, and the Irregular2DSet is passed to the
display logic.

Good luck,
Bill

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