# IterativeClosestPoints

VTKExamples/Python/Filtering/IterativeClosestPoints

### Code

IterativeClosestPoints.py

    from __future__ import print_function

    from vtk import *

    # ============ create source points ==============
    print("Creating source points...")
    sourcePoints = vtk.vtkPoints()
    sourceVertices = vtk.vtkCellArray()

    sp_id = sourcePoints.InsertNextPoint(1.0, 0.1, 0.0)
    sourceVertices.InsertNextCell(1)
    sourceVertices.InsertCellPoint(sp_id)

    sp_id = sourcePoints.InsertNextPoint(0.1, 1.1, 0.0)
    sourceVertices.InsertNextCell(1)
    sourceVertices.InsertCellPoint(sp_id)

    sp_id = sourcePoints.InsertNextPoint(0.0, 0.1, 1.0)
    sourceVertices.InsertNextCell(1)
    sourceVertices.InsertCellPoint(sp_id)

    source = vtk.vtkPolyData()
    source.SetPoints(sourcePoints)
    source.SetVerts(sourceVertices)
    if vtk.VTK_MAJOR_VERSION <= 5:
        source.Update()

    print("Displaying source points...")
    # ============ display source points ==============
    pointCount = 3
    for index in range(pointCount):
        point = [0, 0, 0]
        sourcePoints.GetPoint(index, point)
        print("source point[%s]=%s" % (index, point))

    # ============ create target points ==============
    print("Creating target points...")
    targetPoints = vtk.vtkPoints()
    targetVertices = vtk.vtkCellArray()

    tp_id = targetPoints.InsertNextPoint(1.0, 0.0, 0.0)
    targetVertices.InsertNextCell(1)
    targetVertices.InsertCellPoint(tp_id)

    tp_id = targetPoints.InsertNextPoint(0.0, 1.0, 0.0)
    targetVertices.InsertNextCell(1)
    targetVertices.InsertCellPoint(tp_id)

    tp_id = targetPoints.InsertNextPoint(0.0, 0.0, 1.0)
    targetVertices.InsertNextCell(1)
    targetVertices.InsertCellPoint(tp_id)

    target = vtk.vtkPolyData()
    target.SetPoints(targetPoints)
    target.SetVerts(targetVertices)
    if vtk.VTK_MAJOR_VERSION <= 5:
        target.Update()

    # ============ display target points ==============
    print("Displaying target points...")
    pointCount = 3
    for index in range(pointCount):
        point = [0, 0, 0]
        targetPoints.GetPoint(index, point)
        print("target point[%s]=%s" % (index, point))

    print("Running ICP ----------------")
    # ============ run ICP ==============
    icp = vtk.vtkIterativeClosestPointTransform()
    icp.SetSource(source)
    icp.SetTarget(target)
    icp.GetLandmarkTransform().SetModeToRigidBody()
    # icp.DebugOn()
    icp.SetMaximumNumberOfIterations(20)
    icp.StartByMatchingCentroidsOn()
    icp.Modified()
    icp.Update()

    icpTransformFilter = vtk.vtkTransformPolyDataFilter()
    if vtk.VTK_MAJOR_VERSION <= 5:
        icpTransformFilter.SetInput(source)
    else:
        icpTransformFilter.SetInputData(source)

    icpTransformFilter.SetTransform(icp)
    icpTransformFilter.Update()

    transformedSource = icpTransformFilter.GetOutput()

    # ============ display transformed points ==============
    pointCount = 3
    for index in range(pointCount):
        point = [0, 0, 0]
        transformedSource.GetPoint(index, point)
        print("transformed source point[%s]=%s" % (index, point))