Python VTK: How to use the filter vtkFeatureEdges() with a PolyData() method?

ramiromena · April 23, 2019, 11:04am

Dear VTK community,

I am trying to plot the Boundary Edges of a 3D solid. For my example, I am using a cube that is generated manually (instead of the vtkCubeSource() method) and as a part of the pipeline, the filter vtkFeatureEdges() is used but when the render is launched, the borders are not generated.

The example that I found in the VTK Github used the filter vtkFeatureEdges() together with the vtkCubeSource() method and it works properly. However, I can not use the after-mentioned method as my final goal is to plot a different geometry that will be provided manually. Then, I need to find a way to use the filter or another one that will plot the borders of my solid.

#Case A
#Boundary Edges (defined with vtkCubeSource()) --> Works
featureEdges = vtk.vtkFeatureEdges()
featureEdges.SetInputConnection(cube.GetOutputPort()) 

#Case B
#Boundary Edges (defined with vtkPolyData()) --> Compiles, but do not show borders
featureEdges = vtk.vtkFeatureEdges()
featureEdges.SetInputData(cube)

The expected output is to plot the solid and its border, however at the moment, only the solid is rendered.

Remark: Please, note that I do not want to use the option

cubeActor.GetProperty().EdgeVisibilityOn()

As the solid info comes from a FEM file and that option will display the mesh of my solid and not only the border of the part.

Thanks in advance for your help.

banesullivan · April 23, 2019, 2:45pm

Perhaps you want something like this example from vtki:

Note that vtki is simply a streamlined Python interface to the VTK library and that example uses the extract_edges filter which is implemented with a vtkFeatureEdges filter

And here’s an example with a cube using vtki:

import vtki

cube = vtki.Cube()

edges = cube.extract_edges(20)

p = vtki.Plotter()
p.add_mesh(cube, color=True)
p.add_mesh(edges, color='red', line_width=5)
p.show()