[vtkusers] Delaunay3D Problem

[Marc Schirski]

Hi there,

I've got a problem with the vtkDelaunay3D filter and I'm not quite sure,
what I'm doing wrong...

I've got some rather small points sets of about 6 to 12 points, which I want
to tetrahedrize with the help of the aforementioned filter, but for some
reasons I don't get any satifying results. Depending on the point sets I get
between 0 and 7 tetras, which is obiviously not exactly what one would want.


Basically, I just read in the points (or generate the corresponding
vtkUnstructuredGrid on the fly), stuff them into the vtkDelaunay3D filter,
and keep on working with its output. Playing a little with the filter's
parameters didn't help much. Am I missing something obvious?

I've included two examples at the end of this post - the first one gives
only one tetra, the second one doesn't give me anything...


Actually, these tetrahedrizations are just workarounds for problems I've got
with polyhedral (sp?) cells. I'm trying to visualize data, which has been
generated by the fluid solver StarCD, and as long as the data sets contain
only standard cell types (like hexahedras, wedges, pyramids etc.),
everything works fine, but as they are switching to using more complex cell
types, which are not supported by VTK as far as I know, problems start to
arise...

Most of the new cell types are created from hexahedrons, which have parts of
them cut away. Up to now, I just collect their points and tetrahedrize them.
I know, there might be some problems with topology and continuity...

I should mention, that we write out the data from StarCD with some macros
and convert them to VTK data with self-made converters, because we found the
provided exporters (and importers for VTK) lacking in some respects. Does
anyone have the same problem or even a better idea about dealing with
polyhedral cells?

Thanks in advance and best regards,
	Marc


Example data files:

Resulting in one tetra:
# vtk DataFile Version 3.0
vtk output
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 8 float
0.00537343 0.0372491 0.00427497 0.00444438 0.0367304 0.00437597 0.00534854
0.0366205 0.0043661 
0.00458916 0.036248 0.0049958 0.00435543 0.0370227 0.00550448 0.00528037
0.0370245 0.00518234 
0.00534554 0.0362377 0.00530908 0.004414 0.0372877 0.00428951 
CELL_TYPES 0
POINT_DATA 8

Resulting in no tetra at all:
# vtk DataFile Version 3.0
vtk output
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 8 float
0.004414 0.0372877 0.00428951 0.00537343 0.0372491 0.00427497 0.00444438
0.0367304 0.00437597 
0.00534854 0.0366205 0.0043661 0.00458916 0.036248 0.0049958 0.00435543
0.0370227 0.00550448 
0.00528037 0.0370245 0.00518234 0.00534554 0.0362377 0.00530908 
CELL_TYPES 0
POINT_DATA 8