20000727: Creating Overlays

>From: "Vimal Gopal" <gopal@xxxxxxx>
>Organization: GST
>Keywords: 200007271837.e6RIb5T25977


>    I was wondering whether anyone knew whether there is a way in VisAD
>to apply an overlay to VisAD displays.  By overlay, I mean, geopraphical
>boundries, long/lat lines, etc.  I'm guessing the way to do this is by
>using sets and to "connect the dots".  Any insight is appreciated.

Map lines best described by a UnionSet of Gridded2DSets which each
Gridded2DSet is a segment of the line. A simple example of map lines is
in Rivers.java in visad/examples. In this example, each of the segments
of the river is a Gridded2DSet and a UnionSet is constructed to make the
complete river.

An example of map overlays on a satellite image can be seen by running
'java -Xmx64m SatDisplay' in the visad/examples directory. In this
example, visad.data.mcidas.BaseMapAdapter reads in a remote McIDAS map
file and creates a UnionSet of Gridded2DSets - each of which is a map
line segment. The same can be done with things like Shapefiles. Unidata
has a a ShapefileAdapter which we hope to make available in the near

Don Murray
Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
Unidata WWW Server               http://www.unidata.ucar.edu/
McIDAS Demonstration Machine  http://mcdemo.unidata.ucar.edu/