Hello Haibin,
the issue is very likely not "near" or "far", but the fact that your distal
vessels are very thin compared to the
surface triangle resolution. This causes the Voronoi diagram to degenerate and
the centerline backtracking
to fail.
The workaround in these cases is to use
vmtksurfacesubdivision -method loop
prior to centerline computation in order to artificially increase the
resolution of the surface.
If the number of triangles becomes very large after subdividing, you can add a
decimate step, making it become
vmtksurfacesubdivision -method loop -ifile foo.vtp --pipe vmtksurfacedecimation
-reduction 0.5 --pipe vmtkcenterlines ...
Hope this helps.
Luca
On Apr 20, 2013, at 4:22 AM, Haibin Cai wrote:
> Dear vmtkusers,
> I have a problem of computing centerlines when I position one soure point
> and one target point. If the target point is comparative near, it works well.
> But when I put the target point comparative far, it start from other point.
> It seems that the branch is not connected. Furthermore, there is three
> warnings:
>
> Generic Warning: In
> C:\Users\orobix\Documents\VMTK\vmtk-build\VTK\Common\vtkMath.cxx, line 553
> Unable to factor linear system
>
> Warning: In
> C:\Users\orobix\Documents\VMTK\vmtk-build\VTK\Graphics\vtkDelaunay3D.cxx,
> line 487
> vtkDelaunay3D (0311A688): 149 degenerate triangles encountered, mesh quality
> suspect
>
> Warning: In
> C:\Users\orobix\Documents\VMTK\vmtk\vtkVmtk\ComputationalGeometry\vtkvmtkSteepestDescentLineTracer.cxx,
> line 231
> vtkvmtkSteepestDescentLineTracer (09FC28B0): Degenerate descent detected.
> Target not reached.
> Here is the result
> <1.jpg><2.jpg>
> What does the warning mean? What should I do to let the centerline reach the
> real target point?
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apps and a phenomenal toolset for data science. Developers can use
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