[vtkusers] How to get boundary points???

[Larry]

Thanks for your help, Jeff.
I tried the vtkFeatureEdges, but the output is all the lines in the
polydata, in my case, which the polydata is actually a lot of triangles, so
the output is just all the lines on each triangles.
what I am trying to do is to get the edge of the whole points, which
encloses all the triangles.

Thanks again!
Larry.

----- Original Message ----- 
From: "Jeff Lee" <jeff at cdnorthamerica.com>
To: "david e ignacio" <davidi at cs.uchicago.edu>
Cc: "Larry" <larry74 at 163.com>; <vtkusers at vtk.org>
Sent: Monday, February 23, 2004 7:17 PM
Subject: Re: [vtkusers] How to get boundary points???


> vtkFeatureEdges will give you the boundaryEdges.  I think if you grab
> the output of that filter, it will have the cells (lines) and points you
> require.
> -Jeff
>
> david e ignacio wrote:
>
> > I don't know if there is a prebuilt class that does this.  If you want
> > to implement this yourself, you can look up such things as "Graham's
> > Scan" and also Jarvis's March.  They are fairly simple algorithms that
> > run in O(nlogn) and O(nh) where h is the number of points in the hull.
> > Let me know if you need more help than that.  If I ever get some free
> > time from my schoolwork and this is still needed, I can put something
> > together.
> >
> > Let me know
> > Dave
> >
> > Larry wrote:
> >
> >> Hello, everyone!
> >> I have a vtkPolyData, which is in my case actually a bunch of triangle
> >> cells lie on the same plane, now I want to get the boundary that
> >> enclose all
> >> the triangles.
> >> Simply to say, that I have some points, and I'd like to figure out
> >> the boundary points.
> >>
> >> Is there any way in vtk to do that?
> >>
> >> Thanks!
> >>
> >
> >
> >
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