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//

// Three Frequency Phase Shifting using the Heterodyne Principle

//

// This implementation follows "Reich, Ritter, Thesing, White light heterodyne principle for 3D-measurement", SPIE (1997)

//

// The number of periods in the First and Second frequencies can be chosen freely, but small changes can have a considerable impact on quality.

// The number of phase shifts can be chosen freely (min. 3), and higher values reduce the effects of image noise. They also allow us to filter bad points based on energy at non-First frequencies.

//

#include "AlgorithmPhaseShiftThreeFreq.h"

#include <math.h>

#include "cvtools.h"

#include "algorithmtools.h"

static unsigned int nStepsFirst = 8; // number of shifts/steps in First

static unsigned int nStepsSecond = 8; // number of shifts/steps in Second

static unsigned int nStepsThird = 8; // number of shifts/steps in Third

static float nPeriodsFirst = 24; // First period

static float nPeriodsSecond = 30; // First period

AlgorithmPhaseShiftThreeFreq::AlgorithmPhaseShiftThreeFreq(unsigned int _screenCols, unsigned int _screenRows) : Algorithm(_screenCols, _screenRows){

    // Set N

    N = 2+nStepsFirst+nStepsSecond+nStepsThird;

    // Determine the third number of periods to fulfill the heterodyne condition

    float nPeriodsThird = 1 + 2*nPeriodsSecond - nPeriodsFirst;

    // all on pattern

    cv::Mat allOn(1, screenCols, CV_8UC3, cv::Scalar::all(255));

    patterns.push_back(allOn);

    // all off pattern

    cv::Mat allOff(1, screenCols, CV_8UC3, cv::Scalar::all(0));

    patterns.push_back(allOff);

    // Precompute encoded patterns

    // First encoding patterns

    for(unsigned int i=0; i<nStepsFirst; i++){

        float phase = 2.0*CV_PI/nStepsFirst * i;

        float pitch = screenCols/nPeriodsFirst;

        cv::Mat patternI(1,1,CV_8U);

        patternI = computePhaseVector(screenCols, phase, pitch);

        patterns.push_back(patternI.t());

    }

    // Second encoding patterns

    for(unsigned int i=0; i<nStepsSecond; i++){

        float phase = 2.0*CV_PI/nStepsSecond * i;

        float pitch = screenCols/nPeriodsSecond;

        cv::Mat patternI(1,1,CV_8U);

        patternI = computePhaseVector(screenCols, phase, pitch);

        patterns.push_back(patternI.t());

    }

    // Third encoding patterns

    for(unsigned int i=0; i<nStepsThird; i++){

        float phase = 2.0*CV_PI/nStepsThird * i;

        float pitch = screenCols/nPeriodsThird;

        cv::Mat patternI(1,1,CV_8U);

        patternI = computePhaseVector(screenCols, phase, pitch);

        patterns.push_back(patternI.t());

    }

}

cv::Mat AlgorithmPhaseShiftThreeFreq::getEncodingPattern(unsigned int depth){

    return patterns[depth];

}

void AlgorithmPhaseShiftThreeFreq::get3DPoints(const SMCalibrationParameters & calibration, const std::vector<cv::Mat>& frames0, const std::vector<cv::Mat>& frames1, std::vector<cv::Point3f>& Q, std::vector<cv::Vec3f>& color){

    assert(frames0.size() == N);

    assert(frames1.size() == N);

    int frameRows = frames0[0].rows;

    int frameCols = frames0[0].cols;

    float nPeriodsThird = 1 + 2*nPeriodsSecond - nPeriodsFirst;

    // Rectifying homographies (rotation+projections)

    cv::Size frameSize(frameCols, frameRows);

    cv::Mat R, T;

    // stereoRectify segfaults unless R is double precision

    cv::Mat(calibration.R1).convertTo(R, CV_64F);

    cv::Mat(calibration.T1).convertTo(T, CV_64F);

    cv::Mat R0, R1, P0, P1, QRect;

    cv::stereoRectify(calibration.K0, calibration.k0, calibration.K1, calibration.k1, frameSize, R, T, R0, R1, P0, P1, QRect, 0);

    // Interpolation maps (lens distortion and rectification)

    cv::Mat map0X, map0Y, map1X, map1Y;

    cv::initUndistortRectifyMap(calibration.K0, calibration.k0, R0, P0, frameSize, CV_32F, map0X, map0Y);

    cv::initUndistortRectifyMap(calibration.K1, calibration.k1, R1, P1, frameSize, CV_32F, map1X, map1Y);

    // Gray-scale and remap

    std::vector<cv::Mat> frames0Rect(N);

    std::vector<cv::Mat> frames1Rect(N);

    for(unsigned int i=0; i<N; i++){

        cv::Mat temp;

        cv::cvtColor(frames0[i], temp, CV_RGB2GRAY);

        cv::remap(temp, frames0Rect[i], map0X, map0Y, CV_INTER_LINEAR);

        cv::cvtColor(frames1[i], temp, CV_RGB2GRAY);

        cv::remap(temp, frames1Rect[i], map1X, map1Y, CV_INTER_LINEAR);

    }

    // Decode camera0

    std::vector<cv::Mat> frames0First(frames0Rect.begin()+2, frames0Rect.begin()+2+nStepsFirst);

    std::vector<cv::Mat> frames0Second(frames0Rect.begin()+2+nStepsFirst, frames0Rect.end()-nStepsThird);

    std::vector<cv::Mat> frames0Third(frames0Rect.end()-nStepsThird, frames0Rect.end());

    std::vector<cv::Mat> F0First = getDFTComponents(frames0First);

    cv::Mat up0First;

    cv::phase(F0First[2], -F0First[3], up0First);

    std::vector<cv::Mat> F0Second = getDFTComponents(frames0Second);

    cv::Mat up0Second;

    cv::phase(F0Second[2], -F0Second[3], up0Second);

    std::vector<cv::Mat> F0Third = getDFTComponents(frames0Third);

    cv::Mat up0Third;

    cv::phase(F0Third[2], -F0Third[3], up0Third);

    cv::Mat up0FS = up0Second - up0First;

    up0FS = cvtools::modulo(up0FS, 2.0*CV_PI);

    cv::Mat up0ST = up0Third - up0Second;

    up0ST = cvtools::modulo(up0ST, 2.0*CV_PI);

    cv::Mat up0FST = up0ST - up0FS;

    up0FST = cvtools::modulo(up0FST, 2.0*CV_PI);

    cv::Mat up0F = unwrapWithCue(up0First, up0FST, nPeriodsFirst);

    cv::Mat up0S = unwrapWithCue(up0Second, up0FST, nPeriodsSecond);

    cv::Mat up0T = unwrapWithCue(up0Third, up0FST, nPeriodsThird);

    cv::Mat up0Mean = 1.0/3.0 * (up0F + up0S + up0T);

    cv::Mat up0Range = cv::max(up0F, cv::max(up0S, up0T)) - cv::min(up0F, cv::min(up0S, up0T));

    cv::Mat up0 = up0Mean * screenCols/(2.0*CV_PI);

    cv::Mat amplitude0;

    cv::magnitude(F0First[2], -F0First[3], amplitude0);

    // Decode camera1

    std::vector<cv::Mat> frames1First(frames1Rect.begin()+2, frames1Rect.begin()+2+nStepsFirst);

    std::vector<cv::Mat> frames1Second(frames1Rect.begin()+2+nStepsFirst, frames1Rect.end()-nStepsThird);

    std::vector<cv::Mat> frames1Third(frames1Rect.end()-nStepsThird, frames1Rect.end());

    std::vector<cv::Mat> F1First = getDFTComponents(frames1First);

    cv::Mat up1First;

    cv::phase(F1First[2], -F1First[3], up1First);

    std::vector<cv::Mat> F1Second = getDFTComponents(frames1Second);

    cv::Mat up1Second;

    cv::phase(F1Second[2], -F1Second[3], up1Second);

    std::vector<cv::Mat> F1Third = getDFTComponents(frames1Third);

    cv::Mat up1Third;

    cv::phase(F1Third[2], -F1Third[3], up1Third);

    cv::Mat up1FS = up1Second - up1First;

    up1FS = cvtools::modulo(up1FS, 2.0*CV_PI);

    cv::Mat up1ST = up1Third - up1Second;

    up1ST = cvtools::modulo(up1ST, 2.0*CV_PI);

    cv::Mat up1FST = up1ST - up1FS;

    up1FST = cvtools::modulo(up1FST, 2.0*CV_PI);

    cv::Mat up1F = unwrapWithCue(up1First, up1FST, nPeriodsFirst);

    cv::Mat up1S = unwrapWithCue(up1Second, up1FST, nPeriodsSecond);

    cv::Mat up1T = unwrapWithCue(up1Third, up1FST, nPeriodsThird);

    cv::Mat up1Mean = 1.0/3.0 * (up1F + up1S + up1T);

    cv::Mat up1Range = cv::max(up1F, cv::max(up1S, up1T)) - cv::min(up1F, cv::min(up1S, up1T));

    cv::Mat up1 = up1Mean * screenCols/(2.0*CV_PI);

    cv::Mat amplitude1;

    cv::magnitude(F1First[2], -F1First[3], amplitude1);

    #ifdef QT_DEBUG

        cvtools::writeMat(up0First, "up0First.mat", "up0First");

        cvtools::writeMat(up0Second, "up0Second.mat", "up0Second");

        cvtools::writeMat(up0Third, "up0Third.mat", "up0Third");

        cvtools::writeMat(up0FS, "up0FS.mat", "up0FS");

        cvtools::writeMat(up0ST, "up0ST.mat", "up0ST");

        cvtools::writeMat(up0FST, "up0FST.mat", "up0FST");

        cvtools::writeMat(up0Mean, "up0Mean.mat", "up0Mean");

        cvtools::writeMat(up0Range, "up0Range.mat", "up0Range");

        cvtools::writeMat(up0, "up0.mat", "up0");

        cvtools::writeMat(up1, "up1.mat", "up1");

        cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");

        cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");

        cvtools::writeMat(amplitude1, "amplitude1.mat", "amplitude1");

    #endif

    // color remap

    cv::Mat color0, color1;

    cv::remap(frames0[0], color0, map0X, map0Y, CV_INTER_LINEAR);

    cv::remap(frames1[0], color1, map1X, map1Y, CV_INTER_LINEAR);

    #ifdef QT_DEBUG

        cvtools::writeMat(color0, "color0.mat", "color0");

        cvtools::writeMat(color1, "color1.mat", "color1");

    #endif

    // Occlusion masks

    cv::Mat occlusion0, occlusion1;

    cv::subtract(frames0Rect[0], frames0Rect[1], occlusion0);

    occlusion0 = (occlusion0 > 0.1) & (occlusion0 < 0.98);

    cv::subtract(frames1Rect[0], frames1Rect[1], occlusion1);

    occlusion1 = (occlusion1 > 0.1) & (occlusion1 < 0.98);

    // Threshold on range

    occlusion0 = occlusion0 & (up0Range < 0.05);

    occlusion1 = occlusion1 & (up1Range < 0.05);

//    // Erode occlusion masks

//    cv::Mat strel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(5,5));

//    cv::erode(occlusion0, occlusion0, strel);

//    cv::erode(occlusion1, occlusion1, strel);

    // Threshold on vertical gradient of phase

    cv::Mat edges0;

    cv::Sobel(up0, edges0, -1, 0, 1, 5);

    occlusion0 = occlusion0 & (abs(edges0) < 100);

    cv::Mat edges1;

    cv::Sobel(up1, edges1, -1, 0, 1, 5);

    occlusion1 = occlusion1 & (abs(edges1) < 100);

    #ifdef QT_DEBUG

        cvtools::writeMat(edges0, "edges0.mat", "edges0");

        cvtools::writeMat(edges1, "edges1.mat", "edges1");

    #endif

    #ifdef QT_DEBUG

        cvtools::writeMat(occlusion0, "occlusion0.mat", "occlusion0");

        cvtools::writeMat(occlusion1, "occlusion1.mat", "occlusion1");

    #endif

    // Match phase maps

    int frameRectRows = map0X.rows;

    int frameRectCols = map0X.cols;

    // camera0 against camera1

    std::vector<cv::Vec2f> q0, q1;

    for(int row=0; row<frameRectRows; row++){

        for(int col=0; col<frameRectCols; col++){

            if(!occlusion0.at<char>(row,col))

                continue;

            float up0i = up0.at<float>(row,col);

            for(int col1=0; col1<up1.cols-1; col1++){

                if(!occlusion1.at<char>(row,col1) || !occlusion1.at<char>(row,col1+1))

                    continue;

                float up1Left = up1.at<float>(row,col1);

                float up1Right = up1.at<float>(row,col1+1);

                if((up1Left <= up0i) && (up0i <= up1Right) && (up0i-up1Left < 1.0) && (up1Right-up0i < 1.0) && (up1Right-up1Left > 0.1)){

                    float col1i = col1 + (up0i-up1Left)/(up1Right-up1Left);

                    q0.push_back(cv::Point2f(col, row));

                    q1.push_back(cv::Point2f(col1i, row));

                    break;

                }

            }

        }

    }

    int nMatches = q0.size();

    if(nMatches < 1){

        Q.resize(0);

        color.resize(0);

        return;

    }

    // Retrieve color information

    color.resize(nMatches);

    for(int i=0; i<nMatches; i++){

        cv::Vec3f c0 = color0.at<cv::Vec3f>(q0[i][1], q0[i][0]);

        cv::Vec3f c1 = color1.at<cv::Vec3f>(q1[i][1], q1[i][0]);

        color[i] = 0.5*c0 + 0.5*c1;

    }

    // Triangulate by means of disparity projection

    Q.resize(q0.size());

    cv::Matx44f QRectx = cv::Matx44f(QRect);

    cv::Matx33f R0invx = cv::Matx33f(cv::Mat(R0.t()));

    #pragma omp parallel for

    for(unsigned int i=0; i<q0.size(); i++){

        float disparity = q0[i][0]-q1[i][0];

        cv::Vec4f Qih = QRectx*cv::Vec4f(q0[i][0], q0[i][1], disparity, 1.0);

        float winv = float(1.0)/Qih[3];

        Q[i] = R0invx * cv::Point3f(Qih[0]*winv, Qih[1]*winv, Qih[2]*winv);

    }

}