Re: MetApps ShapefileAdapter

• To: Bill Hibbard <billh@xxxxxxxxxxxxx>
• Subject: Re: MetApps ShapefileAdapter
• From: James Kelly <J.Kelly@xxxxxxxxxx>
• Date: Mon, 27 May 2002 00:11:05 +1000

Thanks Bill,

I'd gladly try the straightforward way, but I can't think of one!

If there was a signature for ScalarMap.setRange which could do something
like:
lonMap.SetRange(0,180,-180,0)
instead of the
lonMap.setRange(0,360) that we are currently using, then that would have
the desired effect I think... but I can't see a way of doing this.

Cheers,

James

Bill Hibbard wrote:
> 
> Hi James,
> 
> There is 'invisible' logic inside VisAD that is supposed
> to detect longitude seems and even irregular seems in
> arbitrary map projections, and reorganize sampling topologies
> to correctly display data. It works in many cases, but also
> still has some mysterious failures. My advice is to try
> doing what you want in a straightforward way, and let us
> know if you run into problems.
> 
> Cheers,
> Bill
> ----------------------------------------------------------
> Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
> hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
> http://www.ssec.wisc.edu/~billh/vis.html
> 
> On Sun, 26 May 2002, James Kelly wrote:
> 
> > Hi Don, Bill et al,
> >
> > On the topic of projections/coordinate systems, I have a question (or
> > two!) about a coordinate system we would like to use.
> >
> > The problem is basically how to handle the "dateline problem".
> >
> > Currently we have an application which represents the entire world by
> > longitudes 0 to 360, using setRange(0.0, 360.0) on the scalar map of
> > Longitude. This is exactly the range that we want, but do not want to
> > use longitudes of 180 to 360 to represent the western hemishphere.
> >
> > So effectively we want a range which goes from 0 to 180, then from -180
> > to 0 on one continuous display (ie dateline in the middle of the
> > display). So both the data and the display (ie labels) reflect this.
> >
> > My impressions from the current discussion are that to achieve this we
> > would need:
> > 1) to define a coordinate system which mapped the native data of (0 to
> > 180; and -180 to 0) onto the (0 to 360) used by the display
> >
> > 2) and define a display side CS consistent with this
> >
> > 3) maybe we might need to fiddle with other display characteristics to
> > ensure labels were consistent?
> >
> > Am I on the right track? If so, I'd be grateful for an indication of how
> > much effort this might involve (ie day(s), week(s) or month(s)).
> >
> > Thanks,
> >
> > James
> >
> >
> > Don Murray wrote:
> > >
> > > Luke-
> > >
> > > "Luke A. Catania (TEC)" wrote:
> > > >
> > > > Is there a way to use a map projection with VisAD?   If so  there 
> > > > example
> > > > code?? After using the DisplayImplJ3D, I was able to get the map of the
> > > > world shape file displayed, but it does not look correct because of the 
> > > > lack
> > > > of a map projection.
> > >
> > > As Bill mentioned, we use a Display side CS in MetApps.
> > > See ucar.unidata.view.geoloc.MapProjectionDisplay.  This
> > > will take either a visad.georef.MapProjection or a
> > > ucar.unidata.geoloc.Projection as input to set the background
> > > projection.  For a version of MapProjectionDisplay that
> > > uses vanilla VisAD (i.e. no Unidata classes), see:
> > >
> > > ftp://ftp.unidata.ucar.edu/pub/dmurray/MapProjectionDisplay.java
> > >
> > > This does not allow you to change projections, though whereas
> > > ucar.unidata.view.geoloc.MapProjectionDisplay does allow changes
> > > by creating a new DisplayRealTupleType with each change.
> > >
> > > Don
> > > *************************************************************
> > > Don Murray                               UCAR Unidata Program
> > > dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
> > > (303) 497-8628                              Boulder, CO 80307
> > > http://www.unidata.ucar.edu/staff/donm
> > > *************************************************************
> >
> > --
> > James Kelly                                          Regional Computing
> > Phone: 61-3-9669-4724 Fax: 61-3-9669-4128     Email: J.Kelly@xxxxxxxxxx
> >

-- 
James Kelly                                          Regional Computing 
Phone: 61-3-9669-4724 Fax: 61-3-9669-4128     Email: J.Kelly@xxxxxxxxxx

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