# IterativeClosestPoints

VTKExamples/Python/Filtering/IterativeClosestPoints

### Code

IterativeClosestPoints.py

    from __future__ import print_function

    import vtk

    def main():
        # ============ 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)

        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)

        # ============ 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()
        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))

    if __name__ == "__main__":
        main()