mesh decimation in python [closed]

Question

I have a high resolution triangular mesh with about 2 million triangles. I want to reduce the number of triangles and vertices to about ~10000 each, while preserving its general shape as much as possible.

I know this can be done in Matlab using reducepatch. Another alternative is qslim package. Also there is decimation functionality in VTK which has python interface, so technically it is possible in python as well. Meshlab is probably available in python as well (?).

How can I do this kind of mesh decimation in python? Examples would be greatly appreciated.

Answer 1

Here is a minimal python prototype translated from its c++ equivalent vtk example (http://www.vtk.org/Wiki/VTK/Examples/Cxx/Meshes/Decimation), as MrPedru22 well suggested.

from vtk import (vtkSphereSource, vtkPolyData, vtkDecimatePro)


def decimation():
    sphereS = vtkSphereSource()
    sphereS.Update()

    inputPoly = vtkPolyData()
    inputPoly.ShallowCopy(sphereS.GetOutput())

    print("Before decimation\n"
          "-----------------\n"
          "There are " + str(inputPoly.GetNumberOfPoints()) + "points.\n"
          "There are " + str(inputPoly.GetNumberOfPolys()) + "polygons.\n")

    decimate = vtkDecimatePro()
    decimate.SetInputData(inputPoly)
    decimate.SetTargetReduction(.10)
    decimate.Update()

    decimatedPoly = vtkPolyData()
    decimatedPoly.ShallowCopy(decimate.GetOutput())

    print("After decimation \n"
          "-----------------\n"
          "There are " + str(decimatedPoly.GetNumberOfPoints()) + "points.\n"
          "There are " + str(decimatedPoly.GetNumberOfPolys()) + "polygons.\n")


if __name__ == "__main__":
    decimation()

Answer 2

I would recommend you to use vtkQuadricDecimation, the quality of the output model is visually better than using vtkDecimatePro (without proper settings).

decimate = vtkQuadricDecimation()
decimate.SetInputData(inputPoly)
decimate.SetTargetReduction(0.9)

One of the most important things is to use Binary representation when saving STL:

stlWriter = vtkSTLWriter()
stlWriter.SetFileName(filename)
stlWriter.SetFileTypeToBinary()
stlWriter.SetInputConnection(decimate.GetOutputPort())
stlWriter.Write()