StreeterFibreGenerator.cpp

/*

Copyright (C) University of Oxford, 2005-2009

University of Oxford means the Chancellor, Masters and Scholars of the
University of Oxford, having an administrative office at Wellington
Square, Oxford OX1 2JD, UK.

This file is part of Chaste.

Chaste is free software: you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, either version 2.1 of the License, or
(at your option) any later version.

Chaste is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details. The offer of Chaste under the terms of the
License is subject to the License being interpreted in accordance with
English Law and subject to any action against the University of Oxford
being under the jurisdiction of the English Courts.

You should have received a copy of the GNU Lesser General Public License
along with Chaste. If not, see <http://www.gnu.org/licenses/>.

*/

#include "StreeterFibreGenerator.hpp"

#include <fstream>
#include <sstream>
#include "OutputFileHandler.hpp"
#include "Exception.hpp"


template<unsigned SPACE_DIM>
typename StreeterFibreGenerator<SPACE_DIM>::RegionType_
    StreeterFibreGenerator<SPACE_DIM>::GetHeartRegion(unsigned nodeIndex) const
{

    if (mDistMapRightVentricle[nodeIndex] >= mDistMapEpicardium[nodeIndex] &&
        mDistMapRightVentricle[nodeIndex] >= mDistMapLeftVentricle[nodeIndex])
    {
        return LEFT_VENTRICLE_WALL;
    }

    if (mDistMapLeftVentricle[nodeIndex] >= mDistMapEpicardium[nodeIndex] &&
        mDistMapLeftVentricle[nodeIndex] >= mDistMapRightVentricle[nodeIndex])
    {
        return RIGHT_VENTRICLE_WALL;
    }

    if (mDistMapEpicardium[nodeIndex] >= mDistMapLeftVentricle[nodeIndex] &&
        mDistMapEpicardium[nodeIndex] >= mDistMapRightVentricle[nodeIndex])
    {
        if (mDistMapLeftVentricle[nodeIndex]
            < LEFT_SEPTUM_SIZE*(mDistMapLeftVentricle[nodeIndex] + mDistMapRightVentricle[nodeIndex]))
        {
            return LEFT_SEPTUM;
        }
        else
        {
            return RIGHT_SEPTUM;
        }
    }

    return UNKNOWN;
}


template<unsigned SPACE_DIM>
double StreeterFibreGenerator<SPACE_DIM>::GetAveragedThickness(
        const unsigned nodeIndex, const std::vector<double>& wallThickness) const
{
    // Initialise the average with the value corresponding to the current node
    double average = wallThickness[nodeIndex];
    unsigned nodes_visited = 1;

    // Use a set to store visited nodes
    std::set<unsigned> visited_nodes;
    visited_nodes.insert(nodeIndex);

    Node<SPACE_DIM>* p_current_node = mrMesh.GetNode(nodeIndex);


    // Loop over the elements containing the given node
    for(typename Node<SPACE_DIM>::ContainingElementIterator element_iterator = p_current_node->ContainingElementsBegin();
        element_iterator != p_current_node->ContainingElementsEnd();
        ++element_iterator)
    {
        // Get a pointer to the container element
        Element<SPACE_DIM,SPACE_DIM>* p_containing_element = mrMesh.GetElement(*element_iterator);

       // Loop over the nodes of the element
       for(unsigned node_local_index=0;
           node_local_index<p_containing_element->GetNumNodes();
           node_local_index++)
       {
            Node<SPACE_DIM>* p_neighbour_node = p_containing_element->GetNode(node_local_index);
            unsigned neighbour_node_index = p_neighbour_node->GetIndex();

            // Check if the neighbour node has already been visited
            if (visited_nodes.find(neighbour_node_index) == visited_nodes.end())
            {
                average += wallThickness[neighbour_node_index];
                visited_nodes.insert(neighbour_node_index);
                nodes_visited++;
            }
       }
    }

    return average/nodes_visited;
}


template<unsigned SPACE_DIM>
void StreeterFibreGenerator<SPACE_DIM>::ProcessLine(
        const std::string& line, std::set<unsigned>& surfaceNodeIndexSet) const
{
    unsigned num_nodes = 0;
    std::stringstream line_stream(line);

    while (!line_stream.eof())
    {
        unsigned item;
        line_stream >> item;
        // Shift the nodes, since we are assuming MEMFEM format (numbered from 1 on)
        surfaceNodeIndexSet.insert(item-1);

        num_nodes++;
    }

    if (num_nodes != SPACE_DIM)
    {
        EXCEPTION("Wrong file format");
    }

}


template<unsigned SPACE_DIM>
void StreeterFibreGenerator<SPACE_DIM>::GetNodesAtSurface(
        const std::string& surfaceFile, std::vector<unsigned>& surfaceVector) const
{
    // Open the file defining the surface
    std::ifstream file_stream;
    file_stream.open(surfaceFile.c_str());
    if (!file_stream.is_open())
    {
        EXCEPTION("Wrong surface definition file name.");
    }

    // Temporal storage for the nodes, helps discarting repeated values
    std::set<unsigned> surface_node_index_set;

    // Loop over all the triangles and add node indexes to the set
    std::string line;
    getline(file_stream, line);
    do
    {
        ProcessLine(line, surface_node_index_set);

        getline(file_stream, line);
    }
    while(!file_stream.eof());

    // Make vector big enough
    surfaceVector.reserve(surface_node_index_set.size());

    // Copy the node indexes from the set to the vector
    for(std::set<unsigned>::iterator node_index_it=surface_node_index_set.begin();
        node_index_it != surface_node_index_set.end();
        node_index_it++)
    {
        surfaceVector.push_back(*node_index_it);
    }

    file_stream.close();
}


template<unsigned SPACE_DIM>
double StreeterFibreGenerator<SPACE_DIM>::GetFibreMaxAngle(
        const c_vector<RegionType_, SPACE_DIM+1>& nodesRegion) const
{
    unsigned lv=0, rv=0;

    for (unsigned index=0; index<SPACE_DIM+1; index++)
    {
        switch (nodesRegion[index])
        {
            case LEFT_VENTRICLE_WALL:
            case LEFT_SEPTUM:
                lv++;
                break;

            case RIGHT_VENTRICLE_WALL:
            case RIGHT_SEPTUM:
                rv++;
                break;

            case UNKNOWN:
                break;
        }
    }

    // If most of the nodes are in the right ventricle
    if (rv>lv)
    {
        return M_PI/4.0;
    }

    // Anywhere else
    return M_PI/3.0;
}

template<unsigned SPACE_DIM>
StreeterFibreGenerator<SPACE_DIM>::StreeterFibreGenerator(TetrahedralMesh<SPACE_DIM,SPACE_DIM>& rMesh)
    : mrMesh(rMesh),
      mFilesSet(false)
{
    mNumNodes = mrMesh.GetNumNodes();
    mNumElements = mrMesh.GetNumElements();
    mpDistanceCalculator = new DistanceMapCalculator<SPACE_DIM>(mrMesh);
}

template<unsigned SPACE_DIM>
StreeterFibreGenerator<SPACE_DIM>::~StreeterFibreGenerator()
{
    delete mpDistanceCalculator;
}

template<unsigned SPACE_DIM>
void StreeterFibreGenerator<SPACE_DIM>::SetSurfaceFiles(
            std::string epicardiumFile,
            std::string rightVentricleFile,
            std::string leftVentricleFile)
{
    mEpiFile = epicardiumFile;
    mRVFile = rightVentricleFile;
    mLVFile = leftVentricleFile;

    mFilesSet = true;
}

template<unsigned SPACE_DIM>
void StreeterFibreGenerator<SPACE_DIM>::GenerateOrthotropicFibreOrientation(
            std::string outputDirectory,
            std::string fibreOrientationFile,
            bool logInfo)
{
    if (!mFilesSet)
    {
        EXCEPTION("Files defining the heart surfaces not set");
    }

    // Open files
    OutputFileHandler handler(outputDirectory, false);
    out_stream p_fibre_file = handler.OpenOutputFile(fibreOrientationFile);
    out_stream p_regions_file, p_thickness_file, p_ave_thickness_file, p_grad_thickness_file;

    if (logInfo)
    {
        p_regions_file  = handler.OpenOutputFile("node_regions.data");
        p_thickness_file = handler.OpenOutputFile("wall_thickness.data");
        p_ave_thickness_file = handler.OpenOutputFile("averaged_thickness.data");
        p_grad_thickness_file = handler.OpenOutputFile("grad_thickness.data");
    }

    // First line of the fibre file: number of elements of the mesh
    *p_fibre_file << mNumElements << std::endl;

    // Get nodes defining each surface
    GetNodesAtSurface(mEpiFile, mEpiSurface);
    GetNodesAtSurface(mRVFile, mRVSurface);
    GetNodesAtSurface(mLVFile, mLVSurface);
    
    CheckVentricleAlignment();

    // Compute the distance map of each surface
    mpDistanceCalculator->ComputeDistanceMap(mEpiSurface, mDistMapEpicardium);
    mpDistanceCalculator->ComputeDistanceMap(mRVSurface, mDistMapRightVentricle);
    mpDistanceCalculator->ComputeDistanceMap(mLVSurface, mDistMapLeftVentricle);

    /*
     * Compute wall thickness parameter, e
     */
    std::vector<double> wall_thickness(mNumNodes);
    for (unsigned node_index=0; node_index<mNumNodes; node_index++)
    {
        double dist_epi, dist_endo;

        RegionType_ node_region = GetHeartRegion(node_index);

        switch(node_region)
        {
            case LEFT_VENTRICLE_WALL:
                dist_epi = mDistMapEpicardium[node_index];
                dist_endo = mDistMapLeftVentricle[node_index];
                break;

            case RIGHT_VENTRICLE_WALL:
                dist_epi = mDistMapEpicardium[node_index];
                dist_endo = mDistMapRightVentricle[node_index];
                break;

            case LEFT_SEPTUM:
                dist_epi = mDistMapRightVentricle[node_index];
                dist_endo = mDistMapLeftVentricle[node_index];
                break;

            case RIGHT_SEPTUM:
                dist_epi = mDistMapLeftVentricle[node_index];
                dist_endo = mDistMapRightVentricle[node_index];
                break;

            case UNKNOWN:
                #define COVERAGE_IGNORE
                std::cerr << "Wrong distances node: " << node_index << "\t"
                          << "Epi " << mDistMapEpicardium[node_index] << "\t"
                          << "RV " << mDistMapRightVentricle[node_index] << "\t"
                          << "LV " << mDistMapLeftVentricle[node_index]
                          << std::endl;

                // Make wall_thickness=0 as in Martin's code
                dist_epi = 1;
                dist_endo = 0;
                break;
                #undef COVERAGE_IGNORE
        }

        wall_thickness[node_index] = dist_endo / (dist_endo + dist_epi);

        if (isnan(wall_thickness[node_index]))
        {
            #define COVERAGE_IGNORE
            /*
             *  A node contained on both epicardium and lv (or rv) surfaces has wall thickness 0/0.
             *  By setting its value to 0 we consider it contained only on the lv (or rv) surface.
             */
            wall_thickness[node_index] = 0;
            #undef COVERAGE_IGNORE
        }

        if (logInfo)
        {
            *p_regions_file << node_region*100 << "\n";
            *p_thickness_file << wall_thickness[node_index] << "\n";
        }
    }

    /*
     *  For each node, average its value of e with the values of all the neighbours
     */
    std::vector<double> averaged_wall_thickness(mNumNodes);
    for (unsigned node_index=0; node_index<mNumNodes; node_index++)
    {
        averaged_wall_thickness[node_index] = GetAveragedThickness(node_index, wall_thickness);

        if (logInfo)
        {
            *p_ave_thickness_file << averaged_wall_thickness[node_index] << "\n";
        }

    }

    /*
     *  Compute the gradient of the averaged wall thickness at the centroid of each tetrahedral
     */
    c_vector<double,SPACE_DIM> grad_ave_wall_thickness;

    for (unsigned element_index=0; element_index<mNumElements; element_index++)
    {
        Element<SPACE_DIM,SPACE_DIM>* p_element = mrMesh.GetElement(element_index);

        /*
         *  The gradient of the averaged thickness at the element is:
         *
         *     grad_ave_wall_thickness[element_index] = ave' * BF * inv(J)
         *
         *  being : ave, averaged thickness values of the nodes defining the element
         *          J,   the Jacobian of the element as defined in class Element.
         *                               (-1 -1 -1)
         *          BF,  basis functions ( 1  0  0)
         *                               ( 0  1  0)
         *                               ( 0  0  1)
         *
         *  Defined as u in Streeter paper
         */

        c_vector<double, SPACE_DIM+1> elem_nodes_ave_thickness;
        double element_averaged_thickness = 0.0;
        c_vector<RegionType_, SPACE_DIM+1> elem_nodes_region;

        for (unsigned local_node_index=0; local_node_index<SPACE_DIM+1; local_node_index++)
        {
            // Get node's global index
            unsigned global_node_index = p_element->GetNode(local_node_index)->GetIndex();

            elem_nodes_ave_thickness[local_node_index] = averaged_wall_thickness[global_node_index];
            elem_nodes_region[local_node_index] = GetHeartRegion(global_node_index);

            // Calculate wall thickness averaged value for the element
            element_averaged_thickness +=  wall_thickness[global_node_index];
        }

        element_averaged_thickness /= SPACE_DIM+1;

        assert (SPACE_DIM==3);

        c_matrix<double, SPACE_DIM+1, SPACE_DIM> basis_functions( zero_matrix<double>(4u,3u) );
        basis_functions(0,0) = basis_functions(0,1) = basis_functions(0,2) = -1.0;
        basis_functions(1,0) = basis_functions(2,1) = basis_functions(3,2) =  1.0;

        c_matrix<double, SPACE_DIM+1, SPACE_DIM> temp;
        c_matrix<double, SPACE_DIM, SPACE_DIM> jacobian, inverse_jacobian;
        double jacobian_det;               
        mrMesh.GetInverseJacobianForElement(element_index, jacobian, jacobian_det, inverse_jacobian);
        noalias(temp) = prod (basis_functions, inverse_jacobian);
        noalias(grad_ave_wall_thickness) = prod(elem_nodes_ave_thickness, temp);
        
        grad_ave_wall_thickness /= norm_2(grad_ave_wall_thickness);

        if (logInfo)
        {
            *p_grad_thickness_file << grad_ave_wall_thickness[0] << " " << grad_ave_wall_thickness[1] << " " << grad_ave_wall_thickness[2] << std::endl;
        }

        /*
         *   Normal to the gradient (v in Streeter paper) which is then the circumferential direction
         * (it will be the fibre direction after rotation)
         *
         *  Computed as the cross product with the x-axis (assuming base-apex axis is x). The output vector is not normal,
         * since the angle between them may be != 90, normalise it.
         */
        c_vector<double, SPACE_DIM> fibre_direction = VectorProduct(grad_ave_wall_thickness, Create_c_vector(1.0, 0.0, 0.0));           
        fibre_direction /= norm_2(fibre_direction);
        
        /*
         *  Longitude direction (w in Streeter paper)
         */
        c_vector<double, SPACE_DIM> longitude_direction = VectorProduct(grad_ave_wall_thickness, fibre_direction);

        /*
         *  Compute fibre to v angle: alpha = R*(1-2e)^3
         *
         *    R is the maximum angle between the fibre and the v axis (heart region dependant)
         *    (1 - 2e)^3 scales it by a value in [-1, 1] defining the rotation of the fibre based
         *       on the position in the wall
         */
        double alpha = GetFibreMaxAngle(elem_nodes_region) * pow( (1 - 2*element_averaged_thickness), 3 );

        /*
         *  Apply alpha rotation about the u axis to the orthonormal basis
         *
         *               ( u(1) v(1) w(1) )
         *   (u, v, w) = ( u(2) v(2) w(2) )
         *               ( u(3) v(3) w(3) )
         * 
         *  The following matrix defines a rotation about the u axis
         * 
         *                 ( 1        0           0      ) (u')
         *   R = (u, v, w) ( 0    cos(alpha) -sin(alpha) ) (v')
         *                 ( 0    sin(alpha)  cos(alpha) ) (w')
         *
         *  The rotated basis is computed like:
         * 
         *                                             ( 1        0           0      )
         *  (u, v_r, w_r ) = R * (u, v, w) = (u, v, w) ( 0    cos(alpha) -sin(alpha) )
         *                                             ( 0    sin(alpha)  cos(alpha) )
         * 
         *  Which simplifies to:
         * 
         *   v_r =  v*cos(alpha) + w*sin(alpha)
         *   w_r = -v*sin(alpha) + w*cos(alpha)
         */
        c_vector<double, SPACE_DIM> rotated_fibre_direction = fibre_direction*cos(alpha) + longitude_direction*sin(alpha);
        c_vector<double, SPACE_DIM> rotated_longitude_direction = -fibre_direction*sin(alpha) + longitude_direction*cos(alpha);


        /*
         * Test the orthonormality of the basis
         */
        assert( fabs(norm_2(rotated_fibre_direction) - 1) < 100*DBL_EPSILON );
        assert( fabs(norm_2(grad_ave_wall_thickness) - 1) < 100*DBL_EPSILON );
        assert( fabs(norm_2(rotated_longitude_direction) - 1) < 100*DBL_EPSILON );

        assert( fabs(inner_prod(rotated_fibre_direction, grad_ave_wall_thickness)) < 100*DBL_EPSILON );
        assert( fabs(inner_prod(rotated_fibre_direction, rotated_longitude_direction)) < 100*DBL_EPSILON);
        assert( fabs(inner_prod(grad_ave_wall_thickness, rotated_longitude_direction)) < 100*DBL_EPSILON);

        /*
         *  Output the direction of the myofibre, the transverse to it in the plane of the myocite laminae and the normal to this laminae (in that order)
         *
         *  See Fig. 1 "Laminar Structure of the Heart: a mathematical model" LeGrice et al. 97
         *
         */
        *p_fibre_file << rotated_fibre_direction[0]     << " " << rotated_fibre_direction[1]     << " "  << rotated_fibre_direction[2]     << " "
                      << grad_ave_wall_thickness[0]     << " " << grad_ave_wall_thickness[1]     << " "  << grad_ave_wall_thickness[2]     << " "
                      << rotated_longitude_direction[0] << " " << rotated_longitude_direction[1] << " "  << rotated_longitude_direction[2] << std::endl;            
    }

    p_fibre_file->close();

    if (logInfo)
    {
        p_regions_file->close();
        p_thickness_file->close();
        p_ave_thickness_file->close();
        p_grad_thickness_file->close();
    }
}

template<unsigned SPACE_DIM>
void StreeterFibreGenerator<SPACE_DIM>::CheckVentricleAlignment()
{
    double min_y_rv=DBL_MAX;
    double max_y_rv=-DBL_MAX;
    double average_y_rv=0.0;
    for (unsigned i=0; i<mRVSurface.size(); i++)
    {
        double y=mrMesh.GetNode(mRVSurface[i])->rGetLocation()[1];
        average_y_rv += y;
        if (y<min_y_rv)
        {
            min_y_rv=y;
        }

        if (y>max_y_rv)
        {
            max_y_rv=y;
        }
    }
    average_y_rv /= mRVSurface.size();

    double min_y_lv=DBL_MAX;
    double max_y_lv=-DBL_MAX;
    double average_y_lv=0.0;
    for (unsigned i=0; i<mLVSurface.size(); i++)
    {
        double y=mrMesh.GetNode(mLVSurface[i])->rGetLocation()[1];
        average_y_lv += y;
        if (y<min_y_lv)
        {
            min_y_lv=y;
        }

        if (y>max_y_lv)
        {
            max_y_lv=y;
        }
    }
    average_y_lv /= mLVSurface.size();

    //If these assertions trip then it means that the heart is not aligned correctly.
    //See the comment above the method signature.
    
    //Check that LV average is not inside the RV interval
    assert(average_y_lv < min_y_rv  || average_y_lv > max_y_rv);

    //Check that RV average is not inside the LV interval
    assert(average_y_rv < min_y_lv  || average_y_rv > max_y_lv);
}

// Explicit instantiation

//template class StreeterFibreGenerator<1>;
//template class StreeterFibreGenerator<2>;
template class StreeterFibreGenerator<3>;

---