WebSVN – seema-scanner – Diff – /src/algorithm/AlgorithmPhaseShiftTwoFreq.cpp


//
// 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"
 
#include <omp.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];
}
 
 
struct StereoRectifyier {
    cv::Mat map0X, map0Y, map1X, map1Y;
    cv::Mat R0, R1, P0, P1, QRect;
};
static void getStereoRectifyier(const SMCalibrationParameters &calibration,
                                const cv::Size& frameSize,
                                StereoRectifyier& stereoRect);
static void determineAmplitudePhaseEnergy(std::vector<cv::Mat>& frames,
                                    cv::Mat& amplitude,
                                    cv::Mat& phase,
                                    cv::Mat& energy);
static void collectPhases(const cv::Mat& phasePrimary,
                          const cv::Mat& phaseSecondary,
                          cv::Mat& phase);
static void matchPhaseMaps(const cv::Mat& occlusion0, const cv::Mat& occlusion1,
                           const cv::Mat& phase0, const cv::Mat& phase1,
                           std::vector<cv::Vec2f>& q0, std::vector<cv::Vec2f>& q1);
static void triangulate(const StereoRectifyier& stereoRect,
                        const std::vector<cv::Vec2f>& q0,
                        const std::vector<cv::Vec2f>& q1,
                        std::vector<cv::Point3f>& Q);
 
 
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);
 
    StereoRectifyier stereoRect;
    getStereoRectifyier(calibration,
                        cv::Size(frames0[0].cols, frames0[0].rows),
                        stereoRect);
 
    // // Erode occlusion masks
    // cv::Mat strel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(5,5));
 
    cv::Mat up0, up1;
    cv::Mat occlusion0, occlusion1;
    cv::Mat color0, color1;
 
    #pragma omp parallel sections
    {
        #pragma omp section
        {
 
            // Gray-scale and remap/rectify
            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],
                          stereoRect.map0X, stereoRect.map0Y,
                          CV_INTER_LINEAR);
            }
 
            cv::cvtColor(frames0[0], color0, CV_BayerBG2RGB);
            cv::remap(color0, color0,
                      stereoRect.map0X, stereoRect.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();
 
            cv::Mat amplitude0Primary, amplitude0Secondary;
            cv::Mat up0Primary, up0Secondary;
            cv::Mat energy0Primary, energy0Secondary;
            determineAmplitudePhaseEnergy(frames0Primary,
                                          amplitude0Primary,
                                          up0Primary,
                                          energy0Primary);
            determineAmplitudePhaseEnergy(frames0Secondary,
                                          amplitude0Secondary,
                                          up0Secondary,
                                          energy0Secondary);
 
            collectPhases(up0Primary, up0Secondary, up0);
 
            // Threshold on energy at primary frequency
            occlusion0 = occlusion0 & (amplitude0Primary > 5.0*nStepsPrimary);
            // Threshold on energy ratios
            occlusion0 = occlusion0 & (amplitude0Primary > 0.25*energy0Primary);
            occlusion0 = occlusion0 & (amplitude0Secondary > 0.25*energy0Secondary);
 
            // // Erode occlusion masks
            // cv::erode(occlusion0, occlusion0, strel);
 
            // Threshold on gradient of phase
            cv::Mat edges0;
            cv::Sobel(up0, edges0, -1, 1, 1, 5);
            occlusion0 = occlusion0 & (abs(edges0) < 10);
 
            #ifdef SM_DEBUG
                cvtools::writeMat(up0Primary, "up0Primary.mat", "up0Primary");
                cvtools::writeMat(up0Secondary, "up0Secondary.mat", "up0Secondary");
                cvtools::writeMat(up0, "up0.mat", "up0");
                cvtools::writeMat(amplitude0Primary,
                                  "amplitude0Primary.mat", "amplitude0Primary");
                cvtools::writeMat(amplitude0Secondary,
                                  "amplitude0Secondary.mat", "amplitude0Secondary");
                cvtools::writeMat(energy0Primary,
                                  "energy0Primary.mat", "energy0Primary");
                cvtools::writeMat(energy0Secondary,
                                  "energy0Secondary.mat", "energy0Secondary");
                cvtools::writeMat(edges0, "edges0.mat", "edges0");
                cvtools::writeMat(occlusion0, "occlusion0.mat", "occlusion0");
                cvtools::writeMat(color0, "color0.mat", "color0");
            #endif
 
        }
        #pragma omp section
        {
 
            // 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],
                          stereoRect.map1X, stereoRect.map1Y,
                          CV_INTER_LINEAR);
            }
 
            cv::cvtColor(frames1[0], color1, CV_BayerBG2RGB);
            cv::remap(color1, color1,
                      stereoRect.map1X, stereoRect.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();
 
            cv::Mat amplitude1Primary, amplitude1Secondary;
            cv::Mat up1Primary, up1Secondary;
            cv::Mat energy1Primary, energy1Secondary;
            determineAmplitudePhaseEnergy(frames1Primary,
                                          amplitude1Primary,
                                          up1Primary,
                                          energy1Primary);
            determineAmplitudePhaseEnergy(frames1Secondary,
                                          amplitude1Secondary,
                                          up1Secondary,
                                          energy1Secondary);
 
            collectPhases(up1Primary, up1Secondary, up1);
 
            // Threshold on energy at primary frequency
            occlusion1 = occlusion1 & (amplitude1Primary > 5.0*nStepsPrimary);
            // Threshold on energy ratios
            occlusion1 = occlusion1 & (amplitude1Primary > 0.25*energy1Primary);
            occlusion1 = occlusion1 & (amplitude1Secondary > 0.25*energy1Secondary);
 
            // // Erode occlusion masks
            // cv::erode(occlusion1, occlusion1, strel);
 
 
            // Threshold on gradient of phase
            cv::Mat edges1;
            cv::Sobel(up1, edges1, -1, 1, 1, 5);
            occlusion1 = occlusion1 & (abs(edges1) < 10);
 
            #ifdef SM_DEBUG
                cvtools::writeMat(up1Primary, "up1Primary.mat", "up1Primary");
                cvtools::writeMat(up1Secondary, "up1Secondary.mat", "up1Secondary");
                cvtools::writeMat(up1, "up1.mat", "up1");
                cvtools::writeMat(amplitude1Primary,
                                  "amplitude1Primary.mat", "amplitude1Primary");
                cvtools::writeMat(amplitude1Secondary,
                                  "amplitude1Secondary.mat", "amplitude1Secondary");
                cvtools::writeMat(energy1Primary,
                                  "energy1Primary.mat", "energy1Primary");
                cvtools::writeMat(energy1Secondary,
                                  "energy1Secondary.mat", "energy1Secondary");
                cvtools::writeMat(edges1, "edges1.mat", "edges1");
                cvtools::writeMat(occlusion1, "occlusion1.mat", "occlusion1");
                cvtools::writeMat(color1, "color1.mat", "color1");
            #endif
 
        }
    }
 
 
    // Match phase maps
 
    // camera0 against camera1
    std::vector<cv::Vec2f> q0, q1;
    matchPhaseMaps(occlusion0, occlusion1, up0, up1, q0, q1);
 
    size_t nMatches = q0.size();
 
    if(nMatches < 1){
        Q.resize(0);
        color.resize(0);
 
        return;
    }
    else {
        // Retrieve color information
        color.resize(nMatches);
        for(unsigned int i=0; i<nMatches; i++){
 
            cv::Vec3b c0 = color0.at<cv::Vec3b>(int(q0[i][1]), int(q0[i][0]));
            cv::Vec3b c1 = color1.at<cv::Vec3b>(int(q1[i][1]), int(q1[i][0]));
 
            color[i] = 0.5*c0 + 0.5*c1;
        }
    }
 
    // Triangulate points
    triangulate(stereoRect, q0, q1, Q);
 
}
 
void getStereoRectifyier(const SMCalibrationParameters &calibration,
                         const cv::Size& frameSize,
                         StereoRectifyier& stereoRect){
 
    // cv::stereoRectify segfaults unless R is double precision
    cv::Mat R, T;
    cv::Mat(calibration.R1).convertTo(R, CV_64F);
    cv::Mat(calibration.T1).convertTo(T, CV_64F);
 
    cv::stereoRectify(calibration.K0, calibration.k0,
                      calibration.K1, calibration.k1,
                      frameSize, R, T,
                      stereoRect.R0, stereoRect.R1,
                      stereoRect.P0, stereoRect.P1,
                      stereoRect.QRect, 0);
 
    // Interpolation maps (lens distortion and rectification)
    cv::initUndistortRectifyMap(calibration.K0, calibration.k0,
                                stereoRect.R0, stereoRect.P0,
                                frameSize, CV_32F,
                                stereoRect.map0X, stereoRect.map0Y);
    cv::initUndistortRectifyMap(calibration.K1, calibration.k1,
                                stereoRect.R1, stereoRect.P1,
                                frameSize, CV_32F,
                                stereoRect.map1X, stereoRect.map1Y);
}
 
void determineAmplitudePhaseEnergy(std::vector<cv::Mat>& frames,
                                   cv::Mat& amplitude,
                                   cv::Mat& phase,
                                   cv::Mat& energy) {
 
    std::vector<cv::Mat> fourier = getDFTComponents(frames);
 
    cv::phase(fourier[2], -fourier[3], phase);
 
    // Signal energy at unit frequency
    cv::magnitude(fourier[2], -fourier[3], amplitude);
 
    // Collected signal energy at higher frequencies
    energy = cv::Mat(phase.rows, phase.cols, CV_32F, cv::Scalar(0.0));
 
    for(unsigned int i=0; i<frames.size()-1; i++){
        cv::Mat magnitude;
        cv::magnitude(fourier[i*2 + 2], fourier[i*2 + 3], magnitude);
        cv::add(energy, magnitude, energy, cv::noArray(), CV_32F);
    }
 
    frames.clear();
}
 
void collectPhases(const cv::Mat& phasePrimary,
                   const cv::Mat& phaseSecondary,
                   cv::Mat& phase) {
    cv::Mat phaseEquivalent = phaseSecondary - phasePrimary;
    phaseEquivalent = cvtools::modulo(phaseEquivalent, 2.0*CV_PI);
    phase = unwrapWithCue(phasePrimary, phaseEquivalent, nPeriodsPrimary);
    phase *= phasePrimary.cols/(2.0*CV_PI);
}
 
 
void matchPhaseMaps(const cv::Mat& occlusion0, const cv::Mat& occlusion1,
                    const cv::Mat& phase0, const cv::Mat& phase1,
                    std::vector<cv::Vec2f>& q0, std::vector<cv::Vec2f>& q1) {
 
    #pragma omp parallel for
    for(int row=0; row<occlusion0.rows; row++){
        for(int col=0; col<occlusion0.cols; col++){
 
            if(!occlusion0.at<char>(row,col))
                continue;
 
            float phase0i = phase0.at<float>(row,col);
            for(int col1=0; col1<phase1.cols-1; col1++){
 
                if(!occlusion1.at<char>(row,col1) || !occlusion1.at<char>(row,col1+1))
                    continue;
 
                float phase1Left = phase1.at<float>(row,col1);
                float phase1Right = phase1.at<float>(row,col1+1);
 
                bool match = (phase1Left <= phase0i)
                              && (phase0i <= phase1Right)
                              && (phase0i-phase1Left < 1.0)
                              && (phase1Right-phase0i < 1.0)
                              && (phase1Right-phase1Left > 0.1);
 
                if(match){
 
                    float col1i = col1 + (phase0i-phase1Left)/(phase1Right-phase1Left);
 
                    #pragma omp critical
                    {
                    q0.push_back(cv::Point2f(col, row));
                    q1.push_back(cv::Point2f(col1i, row));
                    }
                    break;
                }
            }
        }
    }
 
}
 
void triangulate(const StereoRectifyier& stereoRect,
                 const std::vector<cv::Vec2f>& q0,
                 const std::vector<cv::Vec2f>& q1,
                 std::vector<cv::Point3f>& Q) {
 
    // 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);
 
 
    // Triangulate by means of disparity projection
    Q.resize(q0.size());
    cv::Matx44f QRectx = cv::Matx44f(stereoRect.QRect);
    cv::Matx33f R0invx = cv::Matx33f(cv::Mat(stereoRect.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);
    }
}
 

Subversion Repositories seema-scanner

(root)/src/algorithm/AlgorithmPhaseShiftTwoFreq.cpp – Rev 234 → 235

Rev 234		Rev 235
1	`//`	1	`//`
2	`// Two Frequency Phase Shifting using the Heterodyne Principle`	2	`// Two Frequency Phase Shifting using the Heterodyne Principle`
3	`//`	3	`//`
4	`// This implementation follows "Reich, Ritter, Thesing, White light heterodyne`	4	`// This implementation follows "Reich, Ritter, Thesing, White light heterodyne`
5	`// principle for 3D-measurement", SPIE (1997).`	5	`// principle for 3D-measurement", SPIE (1997).`
6	`//`	6	`//`
7	`// Different from the paper, it uses only two different frequencies.`	7	`// Different from the paper, it uses only two different frequencies.`
8	`//`	8	`//`
9	`// The number of periods in the primary frequency can be chosen freely, but`	9	`// The number of periods in the primary frequency can be chosen freely, but`
10	`// small changes can have a considerable impact on quality. The number of`	10	`// small changes can have a considerable impact on quality. The number of`
11	`// phase shifts can be chosen freely (min. 3), and higher values reduce the`	11	`// phase shifts can be chosen freely (min. 3), and higher values reduce the`
12	`// effects of image noise.They also allow us to filter bad points based on`	12	`// effects of image noise.They also allow us to filter bad points based on`
13	`// energy at non-primary frequencies.`	13	`// energy at non-primary frequencies.`
14	`//`	14	`//`
15		15
16	`#include "AlgorithmPhaseShiftTwoFreq.h"`	16	`#include "AlgorithmPhaseShiftTwoFreq.h"`
17	`#include <math.h>`	17	`#include <math.h>`
18		18
19	`#include "cvtools.h"`	19	`#include "cvtools.h"`
20	`#include "algorithmtools.h"`	20	`#include "algorithmtools.h"`
21		21
22	`#include <omp.h>`	22	`#include <omp.h>`
23		23
24	`static unsigned int nStepsPrimary = 16; // number of shifts/steps in primary`	24	`static unsigned int nStepsPrimary = 16; // number of shifts/steps in primary`
25	`static unsigned int nStepsSecondary = 8; // number of shifts/steps in secondary`	25	`static unsigned int nStepsSecondary = 8; // number of shifts/steps in secondary`
26	`static float nPeriodsPrimary = 40; // primary period`	26	`static float nPeriodsPrimary = 40; // primary period`
27		27
28	`AlgorithmPhaseShiftTwoFreq::AlgorithmPhaseShiftTwoFreq(unsigned int _screenCols,`	28	`AlgorithmPhaseShiftTwoFreq::AlgorithmPhaseShiftTwoFreq(unsigned int _screenCols,`
29	`unsigned int _screenRows)`	29	`unsigned int _screenRows)`
30	`: Algorithm(_screenCols, _screenRows) {`	30	`: Algorithm(_screenCols, _screenRows) {`
31		31
32	`// Set N`	32	`// Set N`
33	`N = 2+nStepsPrimary+nStepsSecondary;`	33	`N = 2+nStepsPrimary+nStepsSecondary;`
34		34
35	`// Determine the secondary (wider) period to fulfill the heterodyne condition`	35	`// Determine the secondary (wider) period to fulfill the heterodyne condition`
36	`float nPeriodsSecondary = nPeriodsPrimary + 1;`	36	`float nPeriodsSecondary = nPeriodsPrimary + 1;`
37		37
38	`// all on pattern`	38	`// all on pattern`
39	`cv::Mat allOn(1, screenCols, CV_8UC3, cv::Scalar::all(255));`	39	`cv::Mat allOn(1, screenCols, CV_8UC3, cv::Scalar::all(255));`
40	`patterns.push_back(allOn);`	40	`patterns.push_back(allOn);`