Fortunately, you may not need to use IrregularSets at all. If the data
is merely unevenly spaced, but still a convex grid, as in your code
example, you can use Gridded3DSet.
If you do need to use an Irregular3DSet, you can work around the bug
with the following code:
Irregular3DSet iset = new Irregular3DSet(xyz, samples,
null, null, null, new DelaunayClarkson(samples));
Irregular3DSet iset = new Irregular3DSet(xyz, samples);
This technique works because for small samplings VisAD uses the
DelaunayWatson algorithm by default, which fails with your data, but
boolean success = iset.Delan.test(samples, true);
Also, please ignore the above Delan.test line; it was for debugging and
I had meant to remove it.