Re: Contour Plotting of Ecological Data Using Visad

• To: Nandita Mangal <nandita_mangal@xxxxxxxxx>
• Subject: Re: Contour Plotting of Ecological Data Using Visad
• From: Bill Hibbard <billh@xxxxxxxxxxxxx>
• Date: Fri, 14 Oct 2005 18:29:37 -0500 (CDT)

Nandita,

Please send all questions to the list rather than just
to me (answers come from lots of people).

It has been my own prejudice for years, through Vis5D
and VisAD, to not smooth contours beyond the resolution
of the underlying data. I think the straight lines in
your contours communicate valuable information to the
user, namely that the underlying data are pretty
sparse. On the other hand, VisAD was very much designed
to be extended, and it would certainly be possible to
develop classes for smoother contours. There's even an
on-line tutorial for writing custom DataRenderers. But
it would be a big job.

I am pleased and impressed that you were able to generate
an image from your data so quickly.

Cheers,
Bill

On Fri, 14 Oct 2005, Nandita Mangal wrote:

> Hi there,
> Thank you for your quick reply, the example worked in
> creating the counters! I had one final question that
> currently the contours i have are straight line
> segments forming triangle ( i guess as in an
> interpolation scheme) I was wondering if there is a
> method/class to make the contours as smooth lines in
> Visad.
> thank you,
> Nandita Mangal.
> Attached: Current Contour Image.
>
> --- Bill Hibbard <billh@xxxxxxxxxxxxx> wrote:
>
> > Hi Nandita,
> >
> > There is an example in Section 3.5 of Ugo's VisAD
> > tutorial.
> > However, you'll want to substitute an Irregular2DSet
> > for
> > the Linear2DSet used in that example. Use the
> > Irregular2DSet
> > constructor signature:
> >
> >   public Irregular2DSet(MathType type, float[][]
> > samples)
> >
> > where samples is dimensioned
> > float[2][number_of_points]
> > and you set your lat coordinates into samples[0][i]
> > and lon coordinates into samples[1][i].
> >
> > Contouring from IrregularSets does not generate
> > labels -
> > if you want those then resample the FlatField you
> > create
> > to a Linear2DSet (or other Gridded2DSet) that covers
> > the
> > region of your Irregular2DSet.
> >
> > Good luck,
> > Bill
> >
> > On Fri, 14 Oct 2005, Nandita Mangal wrote:
> >
> > > Hi there,
> > >
> > > Just looked at Visad today and was wondering if I
> > can
> > > use Visad to create contours from ecological data
> > > (consisting of a lat,long and some Z value(say
> > > temperature)) in my application....If yes then
> > could
> > > someone tell me where I should start/ which
> > classes in
> > > Visad to explore to do the above?
> > >
> > > thanks,
> > > Nandita Mangal
> > > San Diego Supercomputer Center
> >
> >
>
>
>
>
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