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#include "AlgorithmLineShift.h"

#include <cmath>

#include "cvtools.h"

#include <opencv2/imgproc.hpp>

#ifndef log2f

#define log2f(x) (log(x)/log(2.0))

#endif

static unsigned int nLineShifts = 8; // number of columns over which each line is shifted

/*

 * The purpose of this function is to convert an unsigned

 * binary number to reflected binary Gray code.

 *

 * The operator >> is shift right. The operator ^ is exclusive or.

 * Source: http://en.wikipedia.org/wiki/Gray_code

 */

static unsigned int binaryToGray(unsigned int num) {

    return (num >> 1) ^ num;

}

/*

 * From Wikipedia: http://en.wikipedia.org/wiki/Gray_code

 * The purpose of this function is to convert a reflected binary

 * Gray code number to a binary number.

 */

static unsigned int grayToBinary(unsigned int num){

    unsigned int mask;

    for(mask = num >> 1; mask != 0; mask = mask >> 1)

        num = num ^ mask;

    return num;

}

/*

 * Return the Nth bit of an unsigned integer number

 */

static bool getBit(int decimal, int N){

    return decimal & 1 << (N-1);

}

/*

 * Return the number of bits set in an integer

 */

static int countBits(int n) {

  unsigned int c; // c accumulates the total bits set in v

  for (c = 0; n>0; c++)

    n &= n - 1; // clear the least significant bit set

  return c;

}

/*

 * Return the position of the least significant bit that is set

 */

static int leastSignificantBitSet(int x){

  if(x == 0)

      return 0;

  int val = 1;

  while(x>>=1)

      val++;

  return val;

}

static inline unsigned int powi(int num, unsigned int exponent){

    if(exponent == 0)

        return 1;

    float res = num;

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

        res *= num;

    return res;

}

static inline unsigned int twopowi(unsigned int exponent){

    return 1 << exponent;

}

// Algorithm

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

    nGrayBits = ceilf(log2f((float)screenCols)) - floorf(log2f((float)nLineShifts));

    N = 2 + 2*nGrayBits + nLineShifts;

    // 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);

    // Gray code patterns

    for(unsigned int p=0; p<nGrayBits; p++){

        cv::Mat pattern(1, screenCols, CV_8UC3);

        cv::Mat patternInv(1, screenCols, CV_8UC3);

        for(unsigned int j=0; j<screenCols; j++){

            unsigned int jGray = binaryToGray(j);

            // Amplitude of channels

            int bit = (int)getBit(jGray, nGrayBits-p);

            pattern.at<cv::Vec3b>(0,j) = cv::Vec3b(255.0*bit,255.0*bit,255.0*bit);

            int invBit = bit^1;

            patternInv.at<cv::Vec3b>(0,j) = cv::Vec3b(255.0*invBit,255.0*invBit,255.0*invBit);

        }

        patterns.push_back(pattern);

        patterns.push_back(patternInv);

    }

    // line shifts

    for(unsigned int p=0; p<nLineShifts; p++){

        cv::Mat pattern(1, screenCols, CV_8UC3, cv::Vec3b(0, 0, 0));

        for(unsigned int j=p; j<screenCols; j+= nLineShifts)

            pattern.at<cv::Vec3b>(0, j) = cv::Vec3b(255, 255, 255);

        patterns.push_back(pattern);

    }

}

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

    return patterns[depth];

}

static cv::Vec3b getColorSubpix(const cv::Mat& img, cv::Point2f pt){

    assert(!img.empty());

    assert(img.channels() == 3);

    int x = (int)pt.x;

    int y = (int)pt.y;

    int x0 = cv::borderInterpolate(x,   img.cols, cv::BORDER_REFLECT_101);

    int x1 = cv::borderInterpolate(x+1, img.cols, cv::BORDER_REFLECT_101);

    int y0 = cv::borderInterpolate(y,   img.rows, cv::BORDER_REFLECT_101);

    int y1 = cv::borderInterpolate(y+1, img.rows, cv::BORDER_REFLECT_101);

    float a = pt.x - (float)x;

    float c = pt.y - (float)y;

    uchar b = (uchar)cvRound((img.at<cv::Vec3b>(y0, x0)[0] * (1.f - a) + img.at<cv::Vec3b>(y0, x1)[0] * a) * (1.f - c)

                           + (img.at<cv::Vec3b>(y1, x0)[0] * (1.f - a) + img.at<cv::Vec3b>(y1, x1)[0] * a) * c);

    uchar g = (uchar)cvRound((img.at<cv::Vec3b>(y0, x0)[1] * (1.f - a) + img.at<cv::Vec3b>(y0, x1)[1] * a) * (1.f - c)

                           + (img.at<cv::Vec3b>(y1, x0)[1] * (1.f - a) + img.at<cv::Vec3b>(y1, x1)[1] * a) * c);

    uchar r = (uchar)cvRound((img.at<cv::Vec3b>(y0, x0)[2] * (1.f - a) + img.at<cv::Vec3b>(y0, x1)[2] * a) * (1.f - c)

                           + (img.at<cv::Vec3b>(y1, x0)[2] * (1.f - a) + img.at<cv::Vec3b>(y1, x1)[2] * a) * c);

    return cv::Vec3b(b, g, r);

}

void getlineCenters(const cv::Mat& linesScanLine, const cv::Mat& codeScanLine, std::vector<cv::Vec4i>& lineCenters){

    int nCols = linesScanLine.cols;

    // fourth order derivative filtering

    cv::Mat der(1, nCols, CV_8U);

    for(int i=2; i<nCols-2; i++)

        der.at<unsigned char>(0, i) = linesScanLine.at<unsigned char>(0, i-2)+linesScanLine.at<unsigned char>(0, i-1)-

                                      linesScanLine.at<unsigned char>(0, i+1)-linesScanLine.at<unsigned char>(0, i+2);

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

        if(der.at<unsigned char>(0, i) > 0 && der.at<unsigned char>(0, i+1) < 0){

            lineCenters.push_back(i, codeScanLine.at<unsigned char>(0, i));

            // TODO: subpixel interpolation, non-max suppression

        }

    }

}

void AlgorithmLineShift::get3DPoints(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);

    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 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

    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(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);

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

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

    }

    //cvtools::writeMat(frames0Rect[0], "frames0Rect_0.mat", "frames0Rect_0");

    //cvtools::writeMat(frames0Rect[1], "frames0Rect_1.mat", "frames0Rect_1");

    //cvtools::writeMat(frames0Rect[20], "frames0Rect_20.mat", "frames0Rect_20");

    //cvtools::writeMat(frames0Rect[21], "frames0Rect_21.mat", "frames0Rect_21");

    // color debayer and remap

    cv::Mat color0Rect, color1Rect;

    cv::cvtColor(frames0[0], color0Rect, CV_BayerBG2RGB);

    cv::remap(color0Rect, color0Rect, map0X, map0Y, CV_INTER_LINEAR);

    cv::cvtColor(frames1[0], color1Rect, CV_BayerBG2RGB);

    cv::remap(color1Rect, color1Rect, map1X, map1Y, CV_INTER_LINEAR);

    int frameRectRows = frames0Rect[0].rows;

    int frameRectCols = frames0Rect[0].cols;

    // occlusion masks

    cv::Mat occlusion0Rect, occlusion1Rect;

    cv::subtract(frames0Rect[0], frames0Rect[1], occlusion0Rect);

    occlusion0Rect = (occlusion0Rect > 20) & (occlusion0Rect < 250);

    cv::subtract(frames1Rect[0], frames1Rect[1], occlusion1Rect);

    occlusion1Rect = (occlusion1Rect > 20) & (occlusion1Rect < 250);

    //cvtools::writeMat(occlusion0Rect, "occlusion0Rect.mat", "occlusion0Rect");

    //cvtools::writeMat(occlusion1Rect, "occlusion1Rect.mat", "occlusion1Rect");

    // erode occlusion masks

    cv::Mat strel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(2,2));

    cv::erode(occlusion0Rect, occlusion0Rect, strel);

    cv::erode(occlusion1Rect, occlusion1Rect, strel);

    // correct for texture modulation and ambient

    cv::Mat A0 = frames0Rect[1];

    cv::Mat M0 = frames0Rect[0]-frames0Rect[1];

    cv::divide(256.0, M0, M0, CV_32F);

    cv::Mat A1 = frames1Rect[1];

    cv::Mat M1 = frames1Rect[0]-frames1Rect[1];

    cv::divide(256.0, M1, M1, CV_32F);

    for(int i=2; i<N; i++){

        cv::multiply(frames0Rect[i]-A0, M0, frames0Rect[i], 1.0, CV_8UC1);

        cv::multiply(frames1Rect[i]-A1, M1, frames1Rect[i], 1.0, CV_8UC1);

    }

    //cvtools::writeMat(frames0Rect[22], "frames0Rect_22.mat", "frames0Rect_22");

    //cvtools::writeMat(frames0Rect[23], "frames0Rect_23.mat", "frames0Rect_23");

    // divide into Gray coding frames and line shift frames

    std::vector<cv::Mat> frames0GrayCode(frames0Rect.begin()+2, frames0Rect.begin()+2+nGrayBits);

    std::vector<cv::Mat> frames0LineShift(frames0Rect.begin()+2+nGrayBits, frames0Rect.end());

    std::vector<cv::Mat> frames1GrayCode(frames1Rect.begin()+2, frames1Rect.begin()+2+nGrayBits);

    std::vector<cv::Mat> frames1LineShift(frames1Rect.begin()+2+nGrayBits, frames1Rect.end());

    // decode patterns

    cv::Mat code0Gray(frameRectRows, frameRectCols, CV_32S, cv::Scalar(0));

    cv::Mat code1Gray(frameRectRows, frameRectCols, CV_32S, cv::Scalar(0));

    // into gray code

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

        cv::Mat temp, bit0, bit1;

        cv::compare(frames0GrayCode[i*2], frames0GrayCode[i*2+1], temp, cv::CMP_GT);

        temp.convertTo(bit0, CV_32S, 1.0/255.0);

        cv::add(code0Gray, bit0*twopowi(Nbits-i-1), code0Gray, cv::noArray(), CV_32S);

        cv::compare(frames1GrayCode[i*2], frames1GrayCode[i*2+1], temp, cv::CMP_GT);

        temp.convertTo(bit1, CV_32S, 1.0/255.0);

        cv::add(code1Gray, bit1*twopowi(Nbits-i-1), code1Gray, cv::noArray(), CV_32S);

    }

    // set occluded pixels to -1

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

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

            if(occlusion0Rect.at<unsigned char>(r,c) == 0)

                code0Gray.at<int>(r,c) = -1;

            if(occlusion1Rect.at<unsigned char>(r,c) == 0)

                code1Gray.at<int>(r,c) = -1;

        }

    }

    // convert to standard binary

    cv::Mat code0Binary(code0Gray.rows, code0Gray.cols, CV_32F);

    cv::Mat code1Binary(code1Gray.rows, code1Gray.cols, CV_32F);

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

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

            if(code0Gray.at<int>(r,c) != -1)

                code0Binary.at<float>(r,c) = grayToBinary(code0Gray.at<int>(r,c));

            if(code1Gray.at<int>(r,c) != -1)

                code1Binary.at<float>(r,c) = grayToBinary(code1Gray.at<int>(r,c));

        }

    }

    //cvtools::writeMat(code0Gray, "code0Gray.mat", "code0Gray");

    //cvtools::writeMat(code1Gray, "code1Gray.mat", "code1Gray");

    // TODO: iterate through all line frames

    cv::Mat lines0 = frames0LineShift[0];

    cv::Mat lines1 = frames1LineShift[0];

    // matching

    std::vector<cv::Vec2f> q0Rect, q1Rect;

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

        // line center data structure containing [x-coordinate (sub-px), region-code]

        std::vector<cv::Vec2f> lineCenters0, lineCenters1;

        // sorted, unique line centers

        getlineCenters(lines0.row(row), code0Binary.row(row), lineCenters0);

        getlineCenters(lines1.row(row), code1Binary.row(row), lineCenters1);

        // match and store

        int i=0, j=0;

        while(i<lineCenters0.size() && j<lineCenters1.size()){

            if(lineCenters0[i][1] == lineCenters1[j][1]){

                q0Rect.push_back(cv::Point2f(lineCenters0[0][0], row));

                q1Rect.push_back(cv::Point2f(lineCenters1[0][0], row));

                i += 1;

                j += 1;

            } else if(lineCenters0[i][1] < lineCenters1[j][1]){

                i += 1;

            } else if(lineCenters0[i][1] > lineCenters1[j][1]){

                j += 1;

            }

        }

    }

    int nMatches = q0Rect.size();

    if(nMatches < 1){

        Q.resize(0);

        color.resize(0);

        return;

    }

    // retrieve color information (at integer coordinates)

    color.resize(nMatches);

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

        cv::Vec3b c0 = color0Rect.at<cv::Vec3b>(q0Rect[i][1], q0Rect[i][0]);

        cv::Vec3b c1 = color1Rect.at<cv::Vec3b>(q1Rect[i][1], q1Rect[i][0]);

//        cv::Vec3b c0 = getColorSubpix(color0Rect, q0Rect[i]);

//        cv::Vec3b c1 = getColorSubpix(color1Rect, q0Rect[i]);

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

    }

    // triangulate points

    cv::Mat QMatHomogenous, QMat;

    cv::triangulatePoints(P0, P1, q0Rect, q1Rect, QMatHomogenous);

    cvtools::convertMatFromHomogeneous(QMatHomogenous, QMat);

    // undo rectifying rotation

    cv::Mat R0Inv;

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

    QMat = R0Inv*QMat;

    cvtools::matToPoints3f(QMat, Q);

}