Curing the "Jaggies"

["Mark Verschell" <markv@xxxxxxxxxxxxxxxxxxx>]

I have a situation where I want to create or "fake" smooth edges to a filled
contour plot. Precisely, I have 2x2 degree data in the Pacific (84x30 points),
with bad values at locations coincident with land. I want to overlay land
contours from the 5 minute Etopo data set. Everything looks great, except that
the filled contours from my 2x2 data have very jagged (staircase) edges - as
expected. E.g.:


     XXXXXXXXXXXX
        XXXXXXXXX
         XXXXXXXX
           XXXXXX
           XXXXXX
           XXXXXX

Where X's indicate my good data points. What I would like to do is "smooth" the
edges to remove the staircase effect. Does anyone know of a good way to do
this?
Unfortunately, I can't just overlay the land, because there are areas on the
boundary of the region (e.g. the Indonesian Sea) where there is no data either.
In addition, there are places where overlaying the land won't completely mask
out missing data regions.

	Thanks, Mark Verschell

P.S. for the missing data points coincident with water points, I am filling in
those regions with a solid color different from the land color. So I would also
be willing to overlay this "water color" over the data, even if it obscures
some of the good points in my data. I.e. I am willing to smooth the edges of my
data field OR overlay a smooth "ocean mask"

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	      Mark Verschell (verschell@coaps.fsu.edu)
	      Center for Ocean and Atmospheric Prediction Studies
	      Florida State University
              2035 E. Paul Dirac Drive
              R.M. Johnson Bldg. - Suite 200
	      Tallahassee, FL  32306-3041
	      (904) 644-6532              (904) 644-4841 (fax)