How to merge two PolyData into one

Development
1

Hello,

I would like to merge two vtkpolydata if it is possible, but I want to know at the end which point comes from which dataset. Also, I want to be sure that BuildLinks() will work and be able to find the correct neighbor points at the end.

I am not sure which is the best approach and if it is feasible.

Thanks

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2

You could identify each PolyData with a scalar point data array (PolyDataIdx). There might be a filter to do this, I’m not sure there is.

Setup a pipeline with vtkAppendPolyData---->vtkCleanPolyData. Add inputs to Append and Update(). Call BuildLinks() on pipeline’s output after clean up.

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3

You can create an array that contains a constant value using vtkArrayCalculator.

This works well if the two meshes do not intersect. If they do then you need to do Boolean mesh operation.

4

Thank you for the information.

I try the following:

union = vtk.vtkBooleanOperationPolyDataFilter()
union.SetOperationToUnion()
union.SetInputData(0, polydata)
union.SetInputData(1, polydata2)
union.Update()

outPoly = union.GetOutput()
outPoly.GetNumberOfCells()
0
outPoly.GetNumberOfPoints()
0

but the output has 0 cells or points. Do I miss something here?

Thanks

5

Boolean mesh operations in VTK do not work reliably (may provide invalid outputs for completely valid inputs, randomly). vtkBool is supposed to work much better.

6

Are the polys 2D or 3D? Last I checked, the Boolean filters didn’t work for polydata with 2D cells. Straight up outputs an empty polydata. What I mean is the BooleanOperation filters will work only when your polydata has a surface that encloses some volume.

7

My polys are 3D, does it mean that it should work? Could you please give me a working example with data?
Thanks

8

Will vtkBool be integrated in the vtk library at some point? The unreliable vtkBooleanOperationPolyDataFilter is a real drawback.

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