[vtkusers] How to get boundary points???

[Jeff Lee]

what does your pipeline look like?  if you were to set BoundaryEdges on, 
Veature, NonManifold, and ManifoldEdges off, you should get the 
boundary-edge lines/points.
-Jeff

Larry wrote:

>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!
>>>>
>>>>        
>>>>
>>>
>>>_______________________________________________
>>>This is the private VTK discussion list. Please keep messages
>>>on-topic. Check the FAQ at: <http://public.kitware.com/cgi-bin/vtkfaq>
>>>Follow this link to subscribe/unsubscribe:
>>>http://www.vtk.org/mailman/listinfo/vtkusers
>>>
>>>
>>>      
>>>
>
>
>_______________________________________________
>This is the private VTK discussion list. 
>Please keep messages on-topic. Check the FAQ at: <http://public.kitware.com/cgi-bin/vtkfaq>
>Follow this link to subscribe/unsubscribe:
>http://www.vtk.org/mailman/listinfo/vtkusers
>
>
>  
>