[vtkusers] Re: Is there any way to preserve some of theoriginalpoints thru decimation?

[Goodwin Lawlor]

Hi Chris,

You could clip out specific areas of the mesh, decimate each separately,
then append (and clean) the parts into one mesh again.

Alternatively, you could change the topology of your mesh to fool
vtkDecimate that internal points (or edges) are boundary points and not to
be touched.

hth

Goodwin

"Chris Zakrewsky" <chriszakrewsky at hotmail.com> wrote in message
news:BAY2-F12dmEB4HGXAwx00041158 at hotmail.com...
> Dear Mathieu,
>
> I am trying to determine whether VTK has such capability exposed
> in API somewhere, because internally, as you stated, it is already used
> for processing boundary vertices.
>
> >What do you call a subset ? Any kind or a particular one?
>
> Example: think a digital terrain model where some polygons
> represent road constructions. The whole data set has to be
> simplified by decimation, yet none of vertices defining any of
> dykes and viaducts should be moved (that assumes that
> they were tagged prior to processing).
>
> >User interaction ?
>
> Either user interaction or tagging affected vertices in some way,
> or both.
>
> Thanks a lot for your time, it is really, really appreciated.
>
> Very best regards,
> /Chris Zakrewsky
>
>
> >From: Mathieu Malaterre <mathieu.malaterre at kitware.com>
> >
> > No I don't think there is such options in vtkDecimate* class. What do
you
> >call a subset ? Any kind or a particular one? Such as boundary vertex ?
If
> >so then yes you can 'freeze' the boundary vertex
> >(BoundaryVertexDeletionOff).
> >
> > Otherwise you'll have to look at the code to implement such enhancement.
> >How do you plan to pass such arbitrary points ? User interaction ?
> (...)
> >Chris Zakrewsky wrote:
> (...)
> >>     Is there any way to preserve some arbitrary subset of vertices
> >>     (from a mesh) unchanged thru the decimation process? (i.e.
freeze
> >>some vertices, while the rest can be decimated by     vtkDecimate or
> >>alike)
> >>
> >>Is this capability available in VTK at all?
> (...)
>
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