[vtkusers] Alternative to vtkDelaunay2D for surface reconstruction or how to get rid of "Edge not recovered, polygon fill suspect"

[Berti Krüger]

Hi Oleksandr.


Thank you very much for your help.



I don't think that the problem here is that the vtkDelaunay2D filter is getting 3D points which don't lie on 2D plane.


The vtkDelaunay2D class documentation states:


"The input to this filter is a list of points specified in 3D, even though the triangulation is 2D. Thus the triangulation is constructed in the x-y plane, and the z coordinate is ignored (although carried through to the output)."



And in my program it works basicly most of the time absolutely perfect. Only in some situations it doesn't work and i get the error "Edge not recovered, polygon fill suspect".


I haven't found out when and why it happens and hoped maybe some of you have a clue here. I don't even understand, what this error message means. Some help here would also be great because it would help to find the error.



Or is the vtkDelaunay2D filter buggy?



I also tried using the vtkDelaunay2D filter with points which all lie in a 2D plane to test if your hypothesis is right:


[cid:5796291d-e8d6-41e1-8c7d-3b64b48d48a7]      [cid:ebff186b-999b-462d-a4e2-b289e41e9e06]


But that didn't change anything. Most of the time it works, but sometimes i get the error message above.



Is vtkDelaunay the only vtk triangulation algorithm built in or are there others i haven't found yet?

So far, when i looked through the documentation, i haven't found anything quite like it. If anybody knows some other triangulation filter in vtk (it can be a simple ear-cut algorithm i need nothing special) it would be great to know.



Thanks again.


Regard,

Berti

________________________________
Von: vtkusers <vtkusers-bounces at public.kitware.com> im Auftrag von Oleksandr Malyushytsky <omalyushytskyvtkuser at gmail.com>
Gesendet: Montag, 15. Oktober 2018 23:33
An: vtkusers at vtk.org
Betreff: Re: [vtkusers] Alternative to vtkDelaunay2D for surface reconstruction or how to get rid of "Edge not recovered, polygon fill suspect"

I  can't  help you with alternative and afraid that you can't use vtkDelaunay2D here, since it assumes that all points lie on 2D plan, while your points are not.

On Sat, Oct 13, 2018 at 9:35 PM Berti Krüger <berti_krueger at hotmail.com<mailto:berti_krueger at hotmail.com>> wrote:
Hello everyone.

In my project i have a standard 3D triangle mesh surface where i select all vertices which lie inside a region (polygon) which is defined by a closed polyline created by an user interaction using the vtkContourWidget:

[cid:inline_01 at geary]

I then create a polygon mesh which has the shape of the vtkContourWidget polygon selection contour line plus the selected part of the underlying mesh and which lies like a sticker or texture on the the given stl mesh surface:

[cid:inline_00 at geary]

For the reconstruction of the surface i use the vtkDelaunay2D filter using all the points of the vtkContourWidget polygon and the mesh surface points as inputs.

This works absolutely great but depending on the used mesh i sometimes get the following error message from the vtkDelaunay2D filter:

"vtkDelaunay2D (0x556183dcfba0): Edge not recovered, polygon fill suspect"


Does anybody know why this happens and what i can do to get rid of this error?

While nice, but since i don't necessarily need the delaunay properties, is there an alternative to the vtkDelaunay2D filter to get a polygon surface mesh given a bunch of points as an input? (points -> surface)


Thank you very much in advance.

Regards,
Berti
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