[vtkusers] Close the gap between a mesh and a planar

[Patrick Bergeron]

I would take a different approach.

I would look at all the edges that have only 1 cell attached, and these are your boundary edges.

For each boundary edge, create 2 triangles (a quad) with 1 or 2 points at z=0. (Create 2 new points at z=0 for this purpose). If you already have a point at that z=0, then reuse it don’t create it.

That approach will create quads all around your geometry connecting to the bottom but will leave the bottom hole open.

Next create a cell connecting all your z=0 points together. Make sure they are ordered in sequential order to create your contour loop.

Done


Sent from my iPhone

On Jul 13, 2018, at 05:10, Jacky Nguyen <jackynguyen.km at gmail.com<mailto:jackynguyen.km at gmail.com>> wrote:

I have converted an .obj mesh file to .stl. I also created a planar geometry as a holder for the mesh object then merge them. However, it contains a gap. Any suggestion how to close the gap vertically so that it becomes a solid object, I have already tried vtkFillHolesFilter, but it won't fill the gap?

The code to create the planar:


implicitPolyDataDistance = vtk.vtkImplicitPolyDataDistance()
implicitPolyDataDistance.SetInput(stl_poly_data)

#create a grid
xCoords = vtk.vtkFloatArray()
for x, i in enumerate(np.linspace(xmin, xmax,50)):
    xCoords.InsertNextValue(i)

yCoords = vtk.vtkFloatArray()
for y, i in enumerate(np.linspace(ymin, ymax, 50)):
    yCoords.InsertNextValue(i)

zCoords = vtk.vtkFloatArray()
for z, i in enumerate(np.linspace(zmin, zmin + 1, 50)):
    zCoords.InsertNextValue(i)

rgrid = vtk.vtkRectilinearGrid()
rgrid.SetDimensions(x + 1, y + 1 , z + 1)
rgrid.SetXCoordinates(xCoords)
rgrid.SetYCoordinates(yCoords)
rgrid.SetZCoordinates(zCoords)
signedDistances = vtk.vtkFloatArray()
signedDistances.SetNumberOfComponents(1)
signedDistances.SetName("SignedDistances")

# Evaluate the signed distance function at all of the grid points
for pointId in range(rgrid.GetNumberOfPoints()):
    p = rgrid.GetPoint(pointId)
    signedDistance = implicitPolyDataDistance.EvaluateFunction(p)
    signedDistances.InsertNextValue(signedDistance)

# add the SignedDistances to the grid
rgrid.GetPointData().SetScalars(signedDistances)

# geometry filter to view the background grid
geometryFilter = vtk.vtkRectilinearGridGeometryFilter()
geometryFilter.SetInputData(rgrid)
geometryFilter.SetExtent(0, x + 1, 0, y + 1, (z + 1) // 2, (z + 1) // 2)
geometryFilter.Update()
# ================ END creating a plane =======================

The code that merge the stl poly data and the plane:

meshAppend = vtk.vtkAppendPolyData()
meshAppend.AddInputData(stl_poly_data)
meshAppend.AddInputData(geometryFilter.GetOutput())
meshAppend.Update()
boundaryClean = vtk.vtkCleanPolyData()
boundaryClean.SetInputData(meshAppend.GetOutput())
boundaryClean.Update()
out = vtk.vtkPolyData()
out.DeepCopy(boundaryClean.GetOutput())

triangleTrans = vtk.vtkTriangleFilter()
triangleTrans.SetInputData(out)
triangleTrans.Update()

fill = vtk.vtkFillHolesFilter()
fill.SetInputData(out)
fill.SetHoleSize(1000000.0)
fill.Update()


A screenshot of what my current mesh is (note: the red line is where i want to close the gap vertically along the z axis: https://i.stack.imgur.com/F9w3c.png

Any suggestion to solve this problem?

Thank you

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