[vtkusers] Problems with vtkClipPolyData and vtkImplicitBoolean

[David Gobbi]

Hi Normanius,

When a vtkPlaneCollection is used for clipping, the clipping is done once
for each plane (so if there are six planes, then the data is clipped six
times).  In general, you can always combine implicit functions in this way:
clip the data with each function (keeping both the "inside" part and the
"outside" part), and then use a boolean to combine the data pieces back
together again.  By properly merging points when combining the pieces back
together, it's possible to do this seamlessly even for "or" operations.

 - David

On Fri, Jan 8, 2016 at 3:36 AM, normanius <juch at zhaw.ch> wrote:

> Hi David
>
> Thanks for the suggestions. I completely understand your concerns regarding
> complexity and difficulties to implement my suggestions properly. I don't
> know VTK so well to write my own algorithm, my hack was the most feasible
> way to go, given the resources.
>
> I had a look at vtkClosedSurfaceClipping - good work. It will serve me as a
> source of inspiration. Thanks for the hint.
>
> As for now, I will go with Cory's suggestion to subclass vtkCylinder for
> issue 1). And for the accuracy problem, I will stick to my hack. If I will
> have time, I will look at it in more detail.
>
> Just a small correction: I don't fully agree with your statement that it is
> just a matter of curved implicit functions. The problem I described relates
> to combined implicit functions, I think one will face the same issues with
> a
> vtkPlaneCollection as well.
>
> Anyhow - thanks for the detailed answers.
>
> Cheers
> Norman
>
>
>
>
>
> --
> View this message in context:
> http://vtk.1045678.n5.nabble.com/Problems-with-vtkClipPolyData-and-vtkImplicitBoolean-tp5735713p5735871.html
> Sent from the VTK - Users mailing list archive at Nabble.com.
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