cxBranchList.cpp

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/*=========================================================================
This file is part of CustusX, an Image Guided Therapy Application.

Copyright (c) SINTEF Department of Medical Technology.
All rights reserved.

CustusX is released under a BSD 3-Clause license.

See Lisence.txt (https://github.com/SINTEFMedtek/CustusX/blob/master/License.txt) for details.
=========================================================================*/
#include "cxBranchList.h"
#include "cxBranch.h"
#include "cxMesh.h"
#include "cxVector3D.h"
#include <vtkPolyData.h>
#include <vtkCardinalSpline.h>
#include "cxLogger.h"
#include <boost/math/special_functions/fpclassify.hpp> // isnan

typedef vtkSmartPointer<class vtkCardinalSpline> vtkCardinalSplinePtr;

namespace cx
{

BranchList::BranchList()
{

}


BranchList::~BranchList()
{
    //  for (int i = 0; i < mBranches.size(); i++)
    //          mBranches[i]->~Branch();
}

void BranchList::addBranch(BranchPtr b)
{
    mBranches.push_back(b);
}

void BranchList::deleteBranch(BranchPtr b)
{
    if(b->getParentBranch())
        b->getParentBranch()->deleteChildBranches();

    for( int i = 0; i < mBranches.size(); i++ )
    {
        if (b == mBranches[i])
        {
            mBranches.erase(mBranches.begin() + i);
            return;
        }
    }
}

void BranchList::deleteAllBranches()
{
    mBranches.clear();
}

std::vector<BranchPtr> BranchList::getBranches()
{
    return mBranches;
}

void BranchList::selectGenerations(int maxGeneration)
{
    std::vector<int> branchNumbersToBeDeleted;
    for( int i = 0; i < mBranches.size(); i++ )
    {
        int generationCounter = 1;
        BranchPtr currentBranch = mBranches[i];
        while (currentBranch->getParentBranch()){
            generationCounter++;
            currentBranch = currentBranch->getParentBranch();
            if (generationCounter > maxGeneration)
            {
                branchNumbersToBeDeleted.push_back(i);
                break;
            }
        }

    }

    for ( int i = branchNumbersToBeDeleted.size() - 1; i >= 0; i-- )
        deleteBranch(mBranches[branchNumbersToBeDeleted[i]]);
}

void BranchList::findBronchoscopeRotation()
{
    BranchPtr trachea = this->getBranches()[0];
    if(trachea)
        calculateBronchoscopeRotation(trachea);
}

void BranchList::calculateBronchoscopeRotation(BranchPtr branch)
// recursive function on all child branches
{
    if(!branch->getParentBranch())
        branch->setBronchoscopeRotation(0);
    else
    {
        double parentRotation = branch->getParentBranch()->getBronchoscopeRotation();
        Eigen::MatrixXd branchOrientations = branch->getOrientations();
        Vector3D branchOrientationStart = branchOrientations.leftCols(std::min(25, (int) branchOrientations.cols())).rowwise().mean();
        Eigen::MatrixXd parentBranchOrientations = branch->getParentBranch()->getOrientations();
        Vector3D parentBranchOrientationEnd = parentBranchOrientations.rightCols(std::min(50, (int) parentBranchOrientations.cols())).rowwise().mean();

        Vector3D bendingDirection = calculateBronchoscopeBendingDirection(parentBranchOrientationEnd, branchOrientationStart);
        double bronchoscopeRotation = bendingDirectionToBronchoscopeRotation(bendingDirection, parentBranchOrientationEnd, parentRotation);

        branch->setBronchoscopeRotation(bronchoscopeRotation);
    }

    branchVector childBranches = branch->getChildBranches();
    for(int i=0; i<childBranches.size(); i++)
        calculateBronchoscopeRotation(childBranches[i]);
}

double bendingDirectionToBronchoscopeRotation(Vector3D bendingDirection, Vector3D parentBranchOrientation, double parentRotation)
{
    double bronchoscopeRotation;

    Vector3D xVector = Vector3D(1,0,0);
    Vector3D up = cross(parentBranchOrientation, xVector).normalized();
    if(up(1) > 0)
        up = -up;

    bronchoscopeRotation = acos( up.dot(bendingDirection) );

    Vector3D N = cross(up, bendingDirection).normalized();

    if(parentBranchOrientation.dot(N) < 0)
        bronchoscopeRotation = -bronchoscopeRotation;

    double rotationDifferenceFromParent = bronchoscopeRotation - parentRotation;

    //Make sure rotation difference is between -180 and 180 deg.
    if ( rotationDifferenceFromParent > M_PI )
        rotationDifferenceFromParent = rotationDifferenceFromParent - 2*M_PI;
    else if ( rotationDifferenceFromParent < -M_PI )
        rotationDifferenceFromParent = rotationDifferenceFromParent + 2*M_PI;

    //Tilt down if needed rotation is less than maxRotationToTiltDown
    if( rotationDifferenceFromParent < (MAX_ROTATION_TO_TILT_DOWN_DEGREES - 180)*M_PI/180 )
        bronchoscopeRotation = bronchoscopeRotation + M_PI;
    else if( rotationDifferenceFromParent > (180 - MAX_ROTATION_TO_TILT_DOWN_DEGREES)*M_PI/180 )
        bronchoscopeRotation = bronchoscopeRotation - M_PI;

    //Not allowing rotation above 180 deg
    rotationDifferenceFromParent = bronchoscopeRotation - parentRotation;
    if( rotationDifferenceFromParent > M_PI )
        bronchoscopeRotation = bronchoscopeRotation - M_PI;
    else if( rotationDifferenceFromParent < -M_PI )
        bronchoscopeRotation = bronchoscopeRotation + M_PI;



    //Sett rotasjon til samme som parent dersom endring er mindre enn 15?? grader

    return bronchoscopeRotation;
}

Vector3D calculateBronchoscopeBendingDirection(Vector3D A, Vector3D B)
{
    A = A.normalized();
    B = B.normalized();
    Vector3D N = A.cross(B);
    N = N.normalized();
    Vector3D C;

    C(2) = 1;
    C(1) = - ( ( N(2) - N(0)*A(2)/A(0) ) / ( N(1) - N(0)*A(1)/A(0) ) ) * C(2);
    if(boost::math::isnan(C(1)) || boost::math::isinf(C(1)))
        C(1) = 0;
    if( similar(A(0),0) )
        C(0) = 0;
    else
        C(0) = - ( A(1)*C(1) + A(2)*C(2) ) / A(0);

    C = C.normalized();

    if (B.dot(C) < 0)
        C = -C;

    return C;
}

void BranchList::smoothOrientations()
{
    for (int i = 0; i < mBranches.size(); i++)
    {
        Eigen::MatrixXd orientations = mBranches[i]->getOrientations();
        Eigen::MatrixXd newOrientations(orientations.rows(),orientations.cols());
        int numberOfColumns = orientations.cols();
        for (int j = 0; j < numberOfColumns; j++)
        {
            newOrientations.col(j) = orientations.block(0,std::max(j-2,0),orientations.rows(),std::min(5,numberOfColumns-j)).rowwise().mean(); //smoothing
            newOrientations.col(j) = newOrientations.col(j) / newOrientations.col(j).norm(); // normalizing
        }
        mBranches[i]->setOrientations(newOrientations);
    }
}

void BranchList::smoothRadius()
{
    for (int i = 0; i < mBranches.size(); i++)
    {
        Eigen::VectorXd radius = mBranches[i]->getRadius();
        Eigen::VectorXd newRadius(radius.rows(),radius.cols());
        int numberOfPoints = radius.size();
        for (int j = 0; j < numberOfPoints; j++)
        {
            newRadius[j] = radius.segment(std::max(j-2,0), std::min(5,numberOfPoints-j)).mean(); //smoothing
        }
        mBranches[i]->setRadius(newRadius);
    }
}

BranchPtr BranchList::findBranchWithLargestRadius()
{
    BranchPtr branchWithLargestRadius = mBranches[0];
    double largestRadius = mBranches[0]->getAverageRadius();

    for (int i = 1; i < mBranches.size(); i++)
    {
        if (mBranches[i]->getAverageRadius() > largestRadius)
        {
            largestRadius = mBranches[i]->getAverageRadius();
            branchWithLargestRadius = mBranches[i];
        }
    }

    return branchWithLargestRadius;
}

void BranchList::interpolateBranchPositions(double resolution /*mm*/)
{

    for (int i = 0; i < mBranches.size(); i++)
    {
        Eigen::MatrixXd positions = mBranches[i]->getPositions();

        if (mBranches[i]->getParentBranch()) // Add parents last position to interpolate between branches
        {
            Eigen::MatrixXd parentPositions = mBranches[i]->getParentBranch()->getPositions();
            Eigen::MatrixXd positionsResized(positions.rows(), positions.cols()+1);
            positionsResized.col(0) = parentPositions.rightCols(1);
            positionsResized.rightCols(positions.cols()) = positions;
            positions = positionsResized;
        }

        std::vector<Eigen::Vector3d> interpolatedPositions;
        for (int j = 0; j < positions.cols()-1; j++)
        {
            int interpolationFactor = static_cast<int>(std::ceil( ( positions.col(j+1) - positions.col(j) ).norm() / resolution ));
            for (int k = 0; k < interpolationFactor; k++){
                Eigen::Vector3d interpolationPoint;
                interpolationPoint[0] = (positions(0,j)*(interpolationFactor-k) + positions(0,j+1)*(k) ) / interpolationFactor;
                interpolationPoint[1] = (positions(1,j)*(interpolationFactor-k) + positions(1,j+1)*(k) ) / interpolationFactor;
                interpolationPoint[2] = (positions(2,j)*(interpolationFactor-k) + positions(2,j+1)*(k) ) / interpolationFactor;
                interpolatedPositions.push_back(interpolationPoint);
            }
        }
        if (mBranches[i]->getParentBranch()) // Remove parents last position after interpolation
        {
            Eigen::MatrixXd positionsResized(positions.rows(), positions.cols()-1);
            positionsResized = positions.rightCols(positionsResized.cols());
            positions = positionsResized;
        }
        Eigen::MatrixXd interpolationResult(3 , interpolatedPositions.size());
        for (int j = 0; j < interpolatedPositions.size(); j++)
        {
            interpolationResult(0,j) = interpolatedPositions[j](0);
            interpolationResult(1,j) = interpolatedPositions[j](1);
            interpolationResult(2,j) = interpolatedPositions[j](2);
        }
        mBranches[i]->setPositions(interpolationResult);
    }

}

void BranchList::smoothBranchPositions(int controlPointDistance)
{
    for (int i = 0; i < mBranches.size(); i++)
    {
        Eigen::MatrixXd positions = mBranches[i]->getPositions();
        int numberOfInputPoints = positions.cols();
        //int controlPointFactor = 10;
        //int numberOfControlPoints = numberOfInputPoints / controlPointFactor;
        double branchLength = (positions.rightCols(1) - positions.leftCols(1)).norm();
        int numberOfControlPoints = std::ceil(branchLength/controlPointDistance);
        numberOfControlPoints = std::max(numberOfControlPoints, 2); // at least two control points

        vtkCardinalSplinePtr splineX = vtkSmartPointer<vtkCardinalSpline>::New();
        vtkCardinalSplinePtr splineY = vtkSmartPointer<vtkCardinalSpline>::New();
        vtkCardinalSplinePtr splineZ = vtkSmartPointer<vtkCardinalSpline>::New();

        //add control points to spline
        for(int j=0; j<numberOfControlPoints; j++)
        {
            int indexP = (j*numberOfInputPoints)/numberOfControlPoints;

            splineX->AddPoint(indexP,positions(0,indexP));
            splineY->AddPoint(indexP,positions(1,indexP));
            splineZ->AddPoint(indexP,positions(2,indexP));
        }
        //Always add the last point to complete spline
        splineX->AddPoint(numberOfInputPoints-1,positions(0,numberOfInputPoints-1));
        splineY->AddPoint(numberOfInputPoints-1,positions(1,numberOfInputPoints-1));
        splineZ->AddPoint(numberOfInputPoints-1,positions(2,numberOfInputPoints-1));

        //evaluate spline - get smoothed positions
        Eigen::MatrixXd smoothingResult(3 , numberOfInputPoints);
        for(int j=0; j<numberOfInputPoints; j++)
        {
            double splineParameter = j;
            smoothingResult(0,j) = splineX->Evaluate(splineParameter);
            smoothingResult(1,j) = splineY->Evaluate(splineParameter);
            smoothingResult(2,j) = splineZ->Evaluate(splineParameter);
        }
        mBranches[i]->setPositions(smoothingResult);
    }
}

void BranchList::findBranchesInCenterline(Eigen::MatrixXd positions_r, bool sortByZindex)
{
    if (sortByZindex)
        positions_r = sortMatrix(2,positions_r);

    Eigen::MatrixXd positionsNotUsed_r = positions_r;

    //  int minIndex;
    int index;
    int splitIndex;
    Eigen::MatrixXd::Index startIndex;
    BranchPtr branchToSplit;
    while (positionsNotUsed_r.cols() > 0)
    {
        if (!mBranches.empty())
        {
            double minDistance = 1000;
            for (int i = 0; i < mBranches.size(); i++)
            {
                std::pair<std::vector<Eigen::MatrixXd::Index>, Eigen::VectorXd> distances;
                distances = dsearchn(positionsNotUsed_r, mBranches[i]->getPositions());
                double d = distances.second.minCoeff(&index);
                if (d < minDistance)
                {
                    minDistance = d;
                    branchToSplit = mBranches[i];
                    startIndex = index;
                    if (minDistance < 2)
                        break;
                }
            }
            std::pair<Eigen::MatrixXd::Index, double> dsearchResult = dsearch(positionsNotUsed_r.col(startIndex) , branchToSplit->getPositions());
            splitIndex = dsearchResult.first;
        }
        else //if this is the first branch. Select the top position (Trachea).
            startIndex = positionsNotUsed_r.cols() - 1;

        std::pair<Eigen::MatrixXd,Eigen::MatrixXd > connectedPointsResult = findConnectedPointsInCT(startIndex , positionsNotUsed_r);
        Eigen::MatrixXd branchPositions = connectedPointsResult.first;
        positionsNotUsed_r = connectedPointsResult.second;

        if (branchPositions.cols() >= 5) //only include brances of length >= 5 points
        {
            BranchPtr newBranch = BranchPtr(new Branch());
            newBranch->setPositions(branchPositions);
            mBranches.push_back(newBranch);

            if (mBranches.size() > 1) // do not try to split another branch when the first branch is processed
            {
                if ((splitIndex + 1 >= 5) && (branchToSplit->getPositions().cols() - splitIndex - 1 >= 5))
                    //do not split branch if the new branch is close to the edge of the branch
                    //if the new branch is not close to one of the edges of the
                    //connected existing branch: Split the existing branch
                {
                    BranchPtr newBranchFromSplit = BranchPtr(new Branch());
                    Eigen::MatrixXd branchToSplitPositions = branchToSplit->getPositions();
                    newBranchFromSplit->setPositions(branchToSplitPositions.rightCols(branchToSplitPositions.cols() - splitIndex - 1));
                    branchToSplit->setPositions(branchToSplitPositions.leftCols(splitIndex + 1));
                    mBranches.push_back(newBranchFromSplit);
                    newBranchFromSplit->setParentBranch(branchToSplit);
                    newBranch->setParentBranch(branchToSplit);
                    newBranchFromSplit->setChildBranches(branchToSplit->getChildBranches());
                    branchVector branchToSplitChildren = branchToSplit->getChildBranches();
                    for (int i = 0; i < branchToSplitChildren.size(); i++)
                        branchToSplitChildren[i]->setParentBranch(newBranchFromSplit);
                    branchToSplit->deleteChildBranches();
                    branchToSplit->addChildBranch(newBranchFromSplit);
                    branchToSplit->addChildBranch(newBranch);
                }
                else if (splitIndex + 1 < 5)
                    // If the new branch is close to the start of the existing
                    // branch: Connect it to the same position start as the
                    // existing branch
                {
                    newBranch->setParentBranch(branchToSplit->getParentBranch());
                    if(branchToSplit->getParentBranch())
                        branchToSplit->getParentBranch()->addChildBranch(newBranch);
                }
                else if (branchToSplit->getPositions().cols() - splitIndex - 1 < 5)
                    // If the new branch is close to the end of the existing
                    // branch: Connect it to the end of the existing branch
                {
                    newBranch->setParentBranch(branchToSplit);
                    branchToSplit->addChildBranch(newBranch);
                }

            }

        }
    }
}

BranchListPtr BranchList::removePositionsForLocalRegistration(Eigen::MatrixXd trackingPositions, double maxDistance)
{
    BranchListPtr retval = BranchListPtr(new BranchList());
    BranchPtr b;
    for (int i = 0; i < mBranches.size(); i++)
    {
        b = BranchPtr(new Branch());
        b->setPositions(mBranches[i]->getPositions());
        retval->addBranch(b);
    }

    std::vector<BranchPtr> branches = retval->getBranches();
    Eigen::MatrixXd positions;
    Eigen::MatrixXd orientations;
    for (int i = 0; i < branches.size(); i++)
    {
        positions = branches[i]->getPositions();
        orientations = branches[i]->getOrientations();
        std::pair<std::vector<Eigen::MatrixXd::Index>, Eigen::VectorXd> distanceData;
        distanceData = dsearchn(positions, trackingPositions);
        Eigen::VectorXd distance = distanceData.second;
        for (int j = positions.cols() - 1; j >= 0; j--)
        {
            if (distance(j) > maxDistance)
            {
                positions = eraseCol(j, positions);
                orientations = eraseCol(j, orientations);
            }
        }
        branches[i]->setPositions(positions);
    }
    return retval;
}

void BranchList::excludeClosePositionsInCTCenterline(double minPointDistance){

    std::vector<BranchPtr> branchVector = this->getBranches();
    for (int i = 0; i < branchVector.size(); i++)
    {
        Eigen::MatrixXd positions = branchVector[i]->getPositions();
        Eigen::MatrixXd orientations = branchVector[i]->getOrientations();

        for (int i = positions.cols()-2; i > 0; i--){
            double distance = (positions.col(i) - positions.col(i+1)).norm();
            if ( distance < minPointDistance )
            {
                positions = eraseCol(i,positions);
                orientations = eraseCol(i,orientations);
            }
        }
        branchVector[i]->setPositions(positions);
    }

}

vtkPolyDataPtr BranchList::createVtkPolyDataFromBranches(bool fullyConnected, bool straightBranches) const
{
    vtkPolyDataPtr retval = vtkPolyDataPtr::New();
    vtkPointsPtr points = vtkPointsPtr::New();
    vtkCellArrayPtr lines = vtkCellArrayPtr::New();

    int positionCounter = 0;
    for (size_t i = 0; i < mBranches.size(); ++i)
    {
        Eigen::MatrixXd positions = mBranches[i]->getPositions();
        if(straightBranches)
        {
            ++positionCounter;
            points->InsertNextPoint(positions(0,0),positions(1,0),positions(2,0));
            points->InsertNextPoint(positions(0,positions.cols()-1),positions(1,positions.cols()-1),positions(2,positions.cols()-1));
            vtkIdType connection[2] = {positionCounter-1, positionCounter};
            lines->InsertNextCell(2, connection);
            ++positionCounter;
        }
        else
        {
            for (int j = 0; j < positions.cols(); ++j)
            {
                ++positionCounter;
                points->InsertNextPoint(positions(0,j),positions(1,j),positions(2,j));
                if (j    < positions.cols()-1)
                {
                    vtkIdType connection[2] = {positionCounter-1, positionCounter};
                    lines->InsertNextCell(2, connection);
                }
            }
        }
    }
    if(fullyConnected)
    {
        int this_branchs_first_point_in_full_polydata_point_list = 0;
        for(size_t i = 0; i < mBranches.size(); ++i)
        {
            if(i>0)
            {
                if(!straightBranches)
                    this_branchs_first_point_in_full_polydata_point_list += mBranches[i-1]->getPositions().cols();
                else
                    this_branchs_first_point_in_full_polydata_point_list += 2;
            }
            int parent_index_in_branch_list = mBranches[i]->findParentIndex(mBranches);

            if(parent_index_in_branch_list > -1)
            {
                int parent_branch_last_point_in_full_polydata = 0;
                for(int j = 0; j <= parent_index_in_branch_list; ++j)
                {
                    if(!straightBranches)
                        parent_branch_last_point_in_full_polydata += mBranches[j]->getPositions().cols() - 1;
                    else
                        parent_branch_last_point_in_full_polydata += (1 + j*2);
                }
                vtkIdType connection[2] = {parent_branch_last_point_in_full_polydata, this_branchs_first_point_in_full_polydata_point_list};
                lines->InsertNextCell(2, connection);
            }

        }

    }
    retval->SetPoints(points);
    retval->SetLines(lines);

    return retval;
}

Eigen::MatrixXd sortMatrix(int rowNumber, Eigen::MatrixXd matrix)
{
    for (int i = 0; i < matrix.cols() - 1; i++)  {
        for (int j = i + 1; j < matrix.cols(); j++) {
            if (matrix(rowNumber,i) > matrix(rowNumber,j)){
                matrix.col(i).swap(matrix.col(j));
            }
        }
    }
    return matrix;
}



Eigen::MatrixXd eraseCol(int removeIndex, Eigen::MatrixXd positions)
{
    positions.block(0 , removeIndex , positions.rows() , positions.cols() - removeIndex - 1) = positions.rightCols(positions.cols() - removeIndex - 1);
    positions.conservativeResize(Eigen::NoChange, positions.cols() - 1);
    return positions;
}

std::pair<Eigen::MatrixXd::Index, double> dsearch(Eigen::Vector3d p, Eigen::MatrixXd positions)
{
    Eigen::MatrixXd::Index index;
    // find nearest neighbour
    (positions.colwise() - p).colwise().squaredNorm().minCoeff(&index);
    double d = (positions.col(index) - p).norm();

    return std::make_pair(index , d);
}

std::pair<std::vector<Eigen::MatrixXd::Index>, Eigen::VectorXd > dsearchn(Eigen::MatrixXd p1, Eigen::MatrixXd p2)
{
    Eigen::MatrixXd::Index index;
    std::vector<Eigen::MatrixXd::Index> indexVector;
    Eigen::VectorXd D(p1.cols());
    for (int i = 0; i < p1.cols(); i++)
    {
        // find nearest neighbour
        (p2.colwise() - p1.col(i)).colwise().squaredNorm().minCoeff(&index);
        D(i) = (p2.col(index) - p1.col(i)).norm();
        indexVector.push_back(index);
    }
    return std::make_pair(indexVector , D);
}

std::pair<Eigen::MatrixXd,Eigen::MatrixXd > findConnectedPointsInCT(int startIndex , Eigen::MatrixXd positionsNotUsed)
{
    //Eigen::MatrixXd branchPositions(positionsNotUsed.rows(), positionsNotUsed.cols());
    Eigen::MatrixXd thisPosition(3,1);
    std::vector<Eigen::MatrixXd> branchPositionsVector;
    thisPosition = positionsNotUsed.col(startIndex);
    branchPositionsVector.push_back(thisPosition); //add first position to branch
    positionsNotUsed = eraseCol(startIndex,positionsNotUsed);; //remove first position from list of remaining points

    while (positionsNotUsed.cols() > 0)
    {
        std::pair<Eigen::MatrixXd::Index, double > minDistance = dsearch(thisPosition, positionsNotUsed);
        Eigen::MatrixXd::Index index = minDistance.first;
        double d = minDistance.second;
        if (d > 3) // more than 3 mm distance to closest point --> branch is compledted
            break;

        thisPosition = positionsNotUsed.col(index);
        positionsNotUsed = eraseCol(index,positionsNotUsed);
        //add position to branch
        branchPositionsVector.push_back(thisPosition);

    }

    Eigen::MatrixXd branchPositions(3,branchPositionsVector.size());

    for (int j = 0; j < branchPositionsVector.size(); j++)
    {
        branchPositions.block(0,j,3,1) = branchPositionsVector[j];
    }

    return std::make_pair(branchPositions, positionsNotUsed);
}

/*
    smoothBranch is smoothing the positions of a centerline branch by using vtkCardinalSpline.
    The degree of smoothing is dependent on the branch radius and the shape of the branch.
    First, the method tests if a straight line from start to end of the branch is sufficient by the condition of
    all positions along the line being within the lumen of the airway (max distance from original centerline
    is set to branch radius).
    If this fails, one more control point is added to the spline at the time, until the condition is fulfilled.
    The control point added for each iteration is the position with the larges deviation from the original/unfiltered
    centerline.
*/
std::vector< Eigen::Vector3d > smoothBranch(BranchPtr branchPtr, int startIndex, Eigen::MatrixXd startPosition)
{
    vtkCardinalSplinePtr splineX = vtkSmartPointer<vtkCardinalSpline>::New();
    vtkCardinalSplinePtr splineY = vtkSmartPointer<vtkCardinalSpline>::New();
    vtkCardinalSplinePtr splineZ = vtkSmartPointer<vtkCardinalSpline>::New();

    double branchRadius = branchPtr->findBranchRadius()/2;

    //add control points to spline

    //add first position
    Eigen::MatrixXd positions = branchPtr->getPositions();
    splineX->AddPoint(0,startPosition(0));
    splineY->AddPoint(0,startPosition(1));
    splineZ->AddPoint(0,startPosition(2));

    // Add last position if no parent branch, else add parents position closest to current branch.
    // Branch positions are stored in order from head to feet (e.g. first position is top of trachea),
    // while route-to-target is generated from target to top of trachea.
    if(!branchPtr->getParentBranch())
    {
        splineX->AddPoint(startIndex,positions(0,0));
        splineY->AddPoint(startIndex,positions(1,0));
        splineZ->AddPoint(startIndex,positions(2,0));
    }
    else
    {
        Eigen::MatrixXd parentPositions = branchPtr->getParentBranch()->getPositions();
        splineX->AddPoint(startIndex,parentPositions(0,parentPositions.cols()-1));
        splineY->AddPoint(startIndex,parentPositions(1,parentPositions.cols()-1));
        splineZ->AddPoint(startIndex,parentPositions(2,parentPositions.cols()-1));
    }

    //Add points until all filtered/smoothed positions are minimum 1 mm inside the airway wall, (within r - 1 mm).
    //This is to make sure the smoothed centerline is within the lumen of the airways.
    double maxAcceptedDistanceToOriginalPosition = std::max(branchRadius - 1, 1.0);
    double maxDistanceToOriginalPosition = maxAcceptedDistanceToOriginalPosition + 1;
    int maxDistanceIndex = -1;
    std::vector< Eigen::Vector3d > smoothingResult;

    //add positions to spline
    while (maxDistanceToOriginalPosition >= maxAcceptedDistanceToOriginalPosition && splineX->GetNumberOfPoints() < startIndex)
    {
        if(maxDistanceIndex > 0)
        {
            //add to spline the position with largest distance to original position
            splineX->AddPoint(maxDistanceIndex,positions(0,startIndex - maxDistanceIndex));
            splineY->AddPoint(maxDistanceIndex,positions(1,startIndex - maxDistanceIndex));
            splineZ->AddPoint(maxDistanceIndex,positions(2,startIndex - maxDistanceIndex));
        }

        //evaluate spline - get smoothed positions
        maxDistanceToOriginalPosition = 0.0;
        smoothingResult.clear();
        for(int j=0; j<=startIndex; j++)
        {
            double splineParameter = j;
            Eigen::Vector3d tempPoint;
            tempPoint(0) = splineX->Evaluate(splineParameter);
            tempPoint(1) = splineY->Evaluate(splineParameter);
            tempPoint(2) = splineZ->Evaluate(splineParameter);
            smoothingResult.push_back(tempPoint);

            //calculate distance to original (non-filtered) position
            double distance = dsearch(tempPoint, positions).second;
            //finding the index with largest distance
            if (distance > maxDistanceToOriginalPosition)
            {
                maxDistanceToOriginalPosition = distance;
                maxDistanceIndex = j;
            }
        }
    }

    return smoothingResult;
}

}//namespace cx