200046: basic topology and the Data Model with geo-locations

>From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
>Organization: .
>Keywords: 200004062200.QAA23842

Hi Bill-

>I originally created the system intrinsic RealTupleType
>for earth location with the (lon, lat, alt) order, but by
>popular demand the system now has intrinsic RealTupleTypes
>for both ways.

Actually, there isn't an intrinsic for LatLonAlt (but it
would be nice).  The SpatialEarth*DTuple intrinsics are
(lon, lat) and (lon, lat, alt), but the coordinate systems
in VisAD (visad.data.mcidas.AREACoordinateSystem, 
visad.bom.Radar*DCoordinateSystem and visad.jmet.GRIBCoordinateSystem)
that use lat/lon have references of order (lat, lon), so
RealTupleType.LatitudeLongtitudeTuple was added.  Most of 
the time that I've seen earth coordinates documented, it has
been (lat,lon) (ex: 40N 105W) rather than (lon,lat).  So,
for me adding alt would give (lat, lon, alt).  Since 
Radar3DCoordinateSystem uses the order (lat,lon,alt) perhaps
having this intrinsic would be good also.  That way people
could choose either way.

Just my $.02

Don Murray                               UCAR Unidata Program
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