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//

// Two Frequency Phase Shifting using the Heterodyne Principle

//

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

// Different from the paper, it uses only two different frequencies.

//

// The number of periods in the primary frequency 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-primary frequencies.

//

#include "AlgorithmPhaseShiftTwoFreq.h"

#include <math.h>

#include "cvtools.h"

#include "algorithmtools.h"

static unsigned int nStepsPrimary = 16; // number of shifts/steps in primary

static unsigned int nStepsSecondary = 8; // number of shifts/steps in secondary

static float nPeriodsPrimary = 40; // primary period

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

    // Set N

    N = 2+nStepsPrimary+nStepsSecondary;

    // Determine the secondary (wider) period to fulfill the heterodyne condition

    float nPeriodsSecondary = nPeriodsPrimary + 1;

    // 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);

    // Primary encoding patterns

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

        float phase = 2.0*CV_PI/nStepsPrimary * i;

        float pitch = screenCols/nPeriodsPrimary;

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

        patternI = computePhaseVector(screenCols, phase, pitch);

        patterns.push_back(patternI.t());

    }

    // Secondary encoding patterns

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

        float phase = 2.0*CV_PI/nStepsSecondary * i;

        float pitch = screenCols/nPeriodsSecondary;

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

        patternI = computePhaseVector(screenCols, phase, pitch);

        patterns.push_back(patternI.t());

    }

}

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

    return patterns[depth];

}

void AlgorithmPhaseShiftTwoFreq::get3DPoints(const SMCalibrationParameters & calibration, const std::vector<cv::Mat>& frames0, const std::vector<cv::Mat>& frames1, std::vector<cv::Point3f>& Q, std::vector<cv::Vec3b>& color){

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

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

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

    cv::Mat R0, P0, P1;

{

    int frameRows = frames0[0].rows;

    int frameCols = frames0[0].cols;

    // 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  R1, 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::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);

    }

    int frameRectRows = map0X.rows;

    int frameRectCols = map0X.cols;

    cv::Mat up0;

    cv::Mat occlusion0;

{

        // Gray-scale and remap

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

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

            cv::Mat temp;

            cv::cvtColor(frames0[i], temp, CV_BayerBG2GRAY);

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

        }

        // Occlusion masks

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

        occlusion0 = (occlusion0 > 25) & (occlusion0 < 250);

        // Decode camera0

        std::vector<cv::Mat> frames0Primary(frames0Rect.begin()+2, frames0Rect.begin()+2+nStepsPrimary);

        std::vector<cv::Mat> frames0Secondary(frames0Rect.begin()+2+nStepsPrimary, frames0Rect.end());

        frames0Rect.clear();

    std::vector<cv::Mat> F0Primary = getDFTComponents(frames0Primary);

    frames0Primary.clear();

    cv::Mat up0Primary;

    cv::phase(F0Primary[2], -F0Primary[3], up0Primary);

    std::vector<cv::Mat> F0Secondary = getDFTComponents(frames0Secondary);

    frames0Secondary.clear();

    cv::Mat up0Secondary;

    cv::phase(F0Secondary[2], -F0Secondary[3], up0Secondary);

    cv::Mat up0Equivalent = up0Secondary - up0Primary;

    up0Equivalent = cvtools::modulo(up0Equivalent, 2.0*CV_PI);

    up0 = unwrapWithCue(up0Primary, up0Equivalent, nPeriodsPrimary);

    up0 *= screenCols/(2.0*CV_PI);

    // Signal energy at unit frequency

    cv::Mat amplitude0Primary, amplitude0Secondary;

    cv::magnitude(F0Primary[2], -F0Primary[3], amplitude0Primary);

    cv::magnitude(F0Secondary[2], -F0Secondary[3], amplitude0Secondary);

    // Collected signal energy at higher frequencies

    cv::Mat energy0Primary(frameRectRows, frameRectCols, CV_32F, cv::Scalar(0.0));

    for(unsigned int i=0; i<nStepsPrimary-1; i++){

        cv::Mat magnitude;

        cv::magnitude(F0Primary[i*2 + 2], F0Primary[i*2 + 3], magnitude);

        cv::add(energy0Primary, magnitude, energy0Primary, cv::noArray(), CV_32F);

    }

    cv::Mat energy0Secondary(frameRectRows, frameRectCols, CV_32F, cv::Scalar(0.0));

    for(unsigned int i=0; i<nStepsSecondary-1; i++){

        cv::Mat magnitude;

        cv::magnitude(F0Secondary[i*2 + 2], F0Secondary[i*2 + 3], magnitude);

        cv::add(energy0Secondary, magnitude, energy0Secondary, cv::noArray(), CV_32F);

    }

    // Threshold on energy at primary frequency

    occlusion0 = occlusion0 & (amplitude0Primary > 5.0*nStepsPrimary);

    // Threshold on energy ratios

    occlusion0 = occlusion0 & (amplitude0Primary > 0.85*energy0Primary);

    occlusion0 = occlusion0 & (amplitude0Secondary > 0.85*energy0Secondary);

    #ifdef SM_DEBUG

        cvtools::writeMat(up0Primary, "up0Primary.mat", "up0Primary");

        cvtools::writeMat(up0Secondary, "up0Secondary.mat", "up0Secondary");

        cvtools::writeMat(up0Equivalent, "up0Equivalent.mat", "up0Equivalent");

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

        cvtools::writeMat(amplitude0Primary, "amplitude0Primary.mat", "amplitude0Primary");

        cvtools::writeMat(energy0Primary, "energy0Primary.mat", "energy0Primary");

        cvtools::writeMat(energy0Secondary, "energy0Secondary.mat", "energy0Secondary");

    #endif

}

    cv::Mat up1;

    cv::Mat occlusion1;

    {

        // Gray-scale and remap

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

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

            cv::Mat temp;

            cv::cvtColor(frames1[i], temp, CV_BayerBG2GRAY);

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

        }

        // Occlusion masks

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

        occlusion1 = (occlusion1 > 25) & (occlusion1 < 250);

        // Decode camera1

        std::vector<cv::Mat> frames1Primary(frames1Rect.begin()+2, frames1Rect.begin()+2+nStepsPrimary);

        std::vector<cv::Mat> frames1Secondary(frames1Rect.begin()+2+nStepsPrimary, frames1Rect.end());

        frames1Rect.clear();

    std::vector<cv::Mat> F1Primary = getDFTComponents(frames1Primary);

    frames1Primary.clear();

    cv::Mat up1Primary;

    cv::phase(F1Primary[2], -F1Primary[3], up1Primary);

    std::vector<cv::Mat> F1Secondary = getDFTComponents(frames1Secondary);

    frames1Secondary.clear();

    cv::Mat up1Secondary;

    cv::phase(F1Secondary[2], -F1Secondary[3], up1Secondary);

    cv::Mat up1Equivalent = up1Secondary - up1Primary;

    up1Equivalent = cvtools::modulo(up1Equivalent, 2.0*CV_PI);

    up1 = unwrapWithCue(up1Primary, up1Equivalent, nPeriodsPrimary);

    up1 *= screenCols/(2.0*CV_PI);

    // Signal energy at unit frequency

    cv::Mat amplitude1Primary, amplitude1Secondary;

    cv::magnitude(F1Primary[2], -F1Primary[3], amplitude1Primary);

    cv::magnitude(F1Secondary[2], -F1Secondary[3], amplitude1Secondary);

    // Collected signal energy at higher frequencies

    cv::Mat energy1Primary(frameRectRows, frameRectCols, CV_32F, cv::Scalar(0.0));

    for(unsigned int i=0; i<nStepsPrimary-1; i++){

        cv::Mat magnitude;

        cv::magnitude(F1Primary[i*2 + 2], F1Primary[i*2 + 3], magnitude);

        cv::add(energy1Primary, magnitude, energy1Primary, cv::noArray(), CV_32F);

    }

    cv::Mat energy1Secondary(frameRectRows, frameRectCols, CV_32F, cv::Scalar(0.0));

    for(unsigned int i=0; i<nStepsSecondary-1; i++){

        cv::Mat magnitude;

        cv::magnitude(F1Secondary[i*2 + 2], F1Secondary[i*2 + 3], magnitude);

        cv::add(energy1Secondary, magnitude, energy1Secondary, cv::noArray(), CV_32F);

    }

    // Threshold on energy at primary frequency

    occlusion1 = occlusion1 & (amplitude1Primary > 5.0*nStepsPrimary);

    // Threshold on energy ratios

    occlusion1 = occlusion1 & (amplitude1Primary > 0.85*energy1Primary);

    occlusion1 = occlusion1 & (amplitude1Secondary > 0.85*energy1Secondary);

    #ifdef SM_DEBUG

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

    #endif

}

//    // 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 gradient of phase

    cv::Mat edges0;

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

    occlusion0 = occlusion0 & (abs(edges0) < 10);

    cv::Mat edges1;

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

    occlusion1 = occlusion1 & (abs(edges1) < 10);

    #ifdef SM_DEBUG

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

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

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

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

    #endif

}

    // Match phase maps

    // 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;

    }

{

    // color debayer and remap

    cv::Mat color0, color1;

    cv::cvtColor(frames0[0], color0, CV_BayerBG2RGB);

    cv::remap(color0, color0, map0X, map0Y, CV_INTER_LINEAR);

    cv::cvtColor(frames1[0], color1, CV_BayerBG2RGB);

    cv::remap(color1, color1, map1X, map1Y, CV_INTER_LINEAR);

    #ifdef SM_DEBUG

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

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

    #endif

        // Retrieve color information

    color.resize(nMatches);

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

        cv::Vec3b c0 = color0.at<cv::Vec3b>(q0[i][1], q0[i][0]);

        cv::Vec3b c1 = color1.at<cv::Vec3b>(q1[i][1], q1[i][0]);

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

    }

}

    // Triangulate points

    cv::Mat QMatHomogenous, QMat;

    cv::triangulatePoints(P0, P1, q0, q1, QMatHomogenous);

    cvtools::convertMatFromHomogeneous(QMatHomogenous, QMat);

    // Undo rectification

    cv::Mat R0Inv;

    cv::Mat(R0.t()).convertTo(R0Inv, CV_32F);

    QMat = R0Inv*QMat;

    cvtools::matToPoints3f(QMat, Q);

}