I just want to add a little to what Tom said. His new version
of DataFitTest3dGridloss.java (in dataFit.jar) produces a very
nice visualization of the situation. I have attached a GIF
snapshot.
As Tom says, this GIF shows that some points lie outside of the
convex hull of the Irregular3DSet, so we expect NaNs from the
interpolation.
The GIF also shows a lot of regularity in the Irregular3DSet,
especially groups of points lying on the same planes and the
same lines. Co-located, co-linear and co-planar points always
give Deluany algorithms trouble. In this example, the co-planar
points generate some tetrahedra with zero volume, and I think
also generate ambiguities in tetrahedralizations.
Tom fixed a bug in Irregular3DSet that manifested in the case
of zero-volume tetrahedra. There may still be disagreements
with interpolations from another system (e.g., Matlab) due to
the ambiguity of tetrahedralization.
Thank for bringing this to our attention, Sebastion.
Cheers,
Bill
> I've implemented and tested a fix to the problem you discovered with
> your interpolation testing - sorry for the delay. Herein you'll find
> two attachments: Irregular3DSet.jar, dataFit.jar. Apply jar xvf to
> the first of these in your visad directory. Jar xvf the second in the
> top level of your classpath; note that this jar file contains my
> modifications of the source you were kind enough to provide. It will
> display the dataset, as well as, any NaN points which will be blue.
> You should see the blue (NaN interpolants) outside the hull of your
> dataset.
>
> Let me know if have any problems,
>
> TomR
>
>
> ------------------------------------------------------------------------------------------------------------------------------------------------
> Name: Irregular3DSet.jar
> Irregular3DSet.jar Type: Java Archive (application/java-archive)
> Encoding: base64
> Download Status: Not downloaded with message
>
> Name: dataFit.jar
> dataFit.jar Type: Java Archive (application/java-archive)
> Encoding: base64
> Download Status: Not downloaded with message
--
----------------------------------------------------------
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
