[vtkusers] Inconsistency in vtkBandedPolyDataContourFilter output

[Claudio Vaccani]

Just for the record, seems the problem was that 
vtkBandedPolyDataContourFilter throws out all the contour values that 
are closer together than FLT_EPSILON*(max-min). This works well for 
evenly spaced contours levels, but produced said problems with 
logarithmic spacing.

So for the time being I'm using my own patched version of the class, but 
it might be worth thinking about making the clipping tolerance 
customizable by the user (or something along those lines).

   Cheers
     Claudio

> Hello everybody,
> I've ran into a rather strange problem when trying to use
> vtkBandedPolyDataContourFilter. The results look fine as long as the
> contours are evenly spaced, but when I set them manually to be
> logarithmically spaced, I get a discrepancy between the bands (primary
> output) and the contour edges (secondary output). More specifically, the
> edges look ok, but some bands are just missing i.e. for some contour
> edges the cells on either side of it have the same cell value.
> 
> Any ideas what I'm doing wrong would be greatly appreciated
> 
>  Thanks in advance
>    Claudio
> 
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