Re: Dynamic Changing of map projections

Hi Geoff-

Nice applet.  Could you elaborate on how you are doing this? Are
you using a display side coordinate system?  Are your projection
coordinate systems something that could go into the visad.georef
core package?

Thanks.

Don

Geoff Freeman wrote:
Hi All,
At the Bureau of Meteorology in Melbourne we needed to be able to
change Map Projections within an application. Since there has
recently been some mention of this sort of thing in the visad list
I made a demonstration applet to show how this feature works for us.

The applet starts with 4 projections available:
Polar Stereographic,
Mercator Lambert Conformal,
and Direct (longitude -> XAxis, Latitude -> YAxis).
In the applet you can select any of these from the menu. The menu
choices labelled with Custom allow you to change the projection
parameters to suit yourself e.g. centre line or standard latitude;
this will then be the one known to the applet.

The map boundaries should be handled correctly. For example if the centre of a Mercator projection (-30) leaves the right edge of the map
at 150 degrees East then the satellite data should split correctly.

Wind barbs should orient correctly when changing to a Polar
Stereographic projection.

I have also included a color legend bar which does not relate to any data but is simply an example of an object which is unaltered
by pan and zoom.

If there is any interest in this I can make it available to others
(it needs a bit of work yet but we currently use it at BoM).

URL:

http://www.bom.gov.au/general/development/visad/MapDemo.shtml

Cheers

Geoff Freeman

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Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
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