Re: Problems to get data into VisAD

• To: Olav Rybatzki <o.rybatzki@xxxxxx>
• Subject: Re: Problems to get data into VisAD
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Wed, 26 Jun 2002 07:22:05 -0500

Hi Olav,

> I  have some problems to get my data into VisAD.
> The data are structured and splited into subdomains. Each  subdomain has
> different values of lengthX and lengthY like the following 2D example
> 
>  _______________________________________________
> |          |           |subd.                       | subd.
>                   |
> |subd.  |subd.  |________________|____________________|
> |_____|_____|
> |   subd.          |
> |___________|
> 
> My first approach was to create DataReferenzImpl, FlatField and
> Gridded2DDoubleSet for each subdomain. With a ScalarMap(MathType,
> Display.RGB) it works. But now when I try to use a Display.IsoContour I
> get a NullPointerException.

We would be very interested to see the complete message
printed by the NullPointerException, including the stack
dump with line numbers.

> Second I tryed to use a ProductSet with an array of Gridded2DDoubleSets.
> 
> FunctionType funcDomainTemperature = new FunctionType (domainTuple,
> tempType);
> 
> for(i=0; i<axis.size (); i++)
> {
>          double[][] pointValues = (double[][])axis.get (i);
>          int[] axisLength = (int[]) dimensions.get (i);
> 
>          domainSet[i] = new Gridded2DDoubleSet (domainTuple, pointValues,
>          axisLength[0],
>          axisLength[1]);
> 
> }
> 
> ProductSet set = new ProductSet (domainSet);
> FlatField val_ff = new FlatField (funcDomainTemperature, set);
> 
> But now I get  a SetException "set and type dimensions don't match" when
> create the FlatField.

The ProductSet is the Cartesian product, so given four Sets
with domain dimension = 2, their ProductSet has domain
dimension = 8. But your MathType dimension = 2, so you get
the message.

If your Gridded2DSets do not overlap, then you want their
UnionSet.

If they do overlap, then the combined topology will not
be a simple union of gridded topologies, and you will
need to merge arrays of explicit locations for each grid
and pass the merged locations to an Irregular2DSet. You
can either compute the merged topology using a DelaunayCustom
object, or you can let Irregular2DSet compute it using a
Delaunay algorithm, which are slow.

Also, I would avoid using "Double" Set (e.g., Gridded2DDoubleSet),
unless your locations really do need double precision. We
use it for combined dates and times, but it shouldn't be
necessary for most spatial locations.

Good luck,
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

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  • Problems to get data into VisAD
    • From: Olav Rybatzki