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

+//
+// 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 primary and secondary 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-primary frequencies.
+//
 #include "AlgorithmPhaseShiftThreeFreq.h"
 #include <math.h>
 #include "cvtools.h"
+#include "algorithmtools.h"
 #ifndef M_PI
     #define M_PI 3.14159265358979323846
 #endif
-static unsigned int nStepsPrimary = 32; // number of shifts/steps in primary
+static unsigned int nStepsPrimary = 8; // number of shifts/steps in primary
-static unsigned int nStepsSecondary = 16; // number of shifts/steps in secondary
+static unsigned int nStepsSecondary = 8; // number of shifts/steps in secondary
-static unsigned int nStepsTertiary = 16; // number of shifts/steps in tertiary
+static unsigned int nStepsTertiary = 8; // number of shifts/steps in tertiary
-static float nPeriodPrimary = 256; // number of primary periods
+static float nPeriodsPrimary = 24; // primary period
-static float nPeriodSecondary = 16; // number of secondary periods
+static float nPeriodsSecondary = 30; // primary period
-// Algorithm
-static cv::Mat computePhaseVector(unsigned int length, float phase, float pitch){
-    cv::Mat phaseVector(length, 1, CV_8UC3);
-    //phaseVector.setTo(0);
-    const float pi = M_PI;
-    // Loop through vector
-    for(int i=0; i<phaseVector.rows; i++){
-        // Amplitude of channels
-        float amp = 0.5*(1+cos(2*pi*i/pitch - phase));
-        phaseVector.at<cv::Vec3b>(i, 0) = cv::Vec3b(255.0*amp, 255.0*amp, 255.0*amp);
-    }
-    return phaseVector;
-}
 AlgorithmPhaseShiftThreeFreq::AlgorithmPhaseShiftThreeFreq(unsigned int _screenCols, unsigned int _screenRows) : Algorithm(_screenCols, _screenRows){
     // Set N
     N = 2+nStepsPrimary+nStepsSecondary+nStepsTertiary;
+    // Determine the tertiary period to fulfill the heterodyne condition
+    float nPeriodsTertiary = (screenCols*nPeriodsPrimary*nPeriodsSecondary)/(nPeriodsPrimary*nPeriodsSecondary+2*screenCols*nPeriodsPrimary-screenCols*nPeriodsSecondary);
     // 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
     const float pi = M_PI;
     // Primary encoding patterns
     for(unsigned int i=0; i<nStepsPrimary; i++){
         float phase = 2.0*pi/nStepsPrimary * i;
-        float pitch = screenCols/nPeriodPrimary;
+        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*pi/nStepsSecondary * i;
-        float pitch = screenCols/nPeriodSecondary;
+        float pitch = screenCols/nPeriodsSecondary;
         cv::Mat patternI(1,1,CV_8U);
         patternI = computePhaseVector(screenCols, phase, pitch);
         patterns.push_back(patternI.t());
+    }
     // Tertiary encoding patterns
     for(unsigned int i=0; i<nStepsTertiary; i++){
         float phase = 2.0*pi/nStepsTertiary * i;
-        float pitch = screenCols;
+        float pitch = screenCols/nPeriodsTertiary;
         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];
+}
-//// Absolute phase from 3 frames
-//static cv::Mat getPhase(const cv::Mat I1, const cv::Mat I2, const cv::Mat I3){
-//    cv::Mat_<float> I1_(I1);
-//    cv::Mat_<float> I2_(I2);
-//    cv::Mat_<float> I3_(I3);
-//    cv::Mat phase;
-//    // One call approach
-//    cv::phase(2.0*I1_-I3_-I2_, sqrt(3.0)*(I2_-I3_), phase);
-//    return phase;
-//}
-// Phase unwrapping by means of a phase cue
-static cv::Mat unwrapWithCue(const cv::Mat up, const cv::Mat upCue, float nPhases){
-    const float pi = M_PI;
-    // Determine number of jumps
-    cv::Mat P = (upCue*nPhases-up)/(2.0*pi);
-    // Round to integers
-    P.convertTo(P, CV_8U);
-    P.convertTo(P, CV_32F);
-    // Add to phase
-    cv::Mat upUnwrapped = up + P*2*pi;
-    // Scale to range [0; 2pi]
-    upUnwrapped *= 1.0/nPhases;
-    return upUnwrapped;
-}
-// Absolute phase and magnitude from N frames
-static std::vector<cv::Mat> getDFTComponents(const std::vector<cv::Mat> frames){
-    unsigned int N = frames.size();
-//    std::vector<cv::Mat> framesReverse = frames;
-//    std::reverse(framesReverse.begin(), framesReverse.end());
-    // DFT approach
-    cv::Mat I;
-    cv::merge(frames, I);
-    unsigned int w = I.cols;
-    unsigned int h = I.rows;
-    I = I.reshape(1, h*w);
-    I.convertTo(I, CV_32F);
-    cv::Mat fI;
-    cv::dft(I, fI, cv::DFT_ROWS + cv::DFT_COMPLEX_OUTPUT);
-    fI = fI.reshape(N*2, h);
-    std::vector<cv::Mat> fIcomp;
-    cv::split(fI, fIcomp);
-    return fIcomp;
-}
 void AlgorithmPhaseShiftThreeFreq::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){
     const float pi = M_PI;
     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 (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_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);
+    }
     // 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()-nStepsTertiary);
     std::vector<cv::Mat> frames0Tertiary(frames0Rect.end()-nStepsTertiary, frames0Rect.end());
     std::vector<cv::Mat> F0Primary = getDFTComponents(frames0Primary);
     cv::Mat up0Primary;
     cv::phase(F0Primary[2], -F0Primary[3], up0Primary);
     std::vector<cv::Mat> F0Secondary = getDFTComponents(frames0Secondary);
     cv::Mat up0Secondary;
     cv::phase(F0Secondary[2], -F0Secondary[3], up0Secondary);
     std::vector<cv::Mat> F0Tertiary = getDFTComponents(frames0Tertiary);
     cv::Mat up0Tertiary;
     cv::phase(F0Tertiary[2], -F0Tertiary[3], up0Tertiary);
+    cv::Mat up0EquivalentPS = up0Primary - up0Secondary;
+    up0EquivalentPS = cvtools::modulo(up0EquivalentPS, 2.0*pi);
-    cv::Mat up0Unwrap = unwrapWithCue(up0Secondary, up0Tertiary, nPeriodSecondary);
+    cv::Mat up0EquivalentST = up0Secondary - up0Tertiary;
+    up0EquivalentST = cvtools::modulo(up0EquivalentST, 2.0*pi);
+    cv::Mat up0Equivalent = up0EquivalentPS - up0EquivalentST;
+    up0Equivalent = cvtools::modulo(up0Equivalent, 2.0*pi);
-    cv::Mat up0 = unwrapWithCue(up0Primary, up0Unwrap, nPeriodPrimary);
+    cv::Mat up0 = unwrapWithCue(up0Primary, up0Equivalent, (float)screenCols/nPeriodsPrimary);
     up0 *= screenCols/(2.0*pi);
     cv::Mat amplitude0;
     cv::magnitude(F0Primary[2], -F0Primary[3], amplitude0);
     // 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()-nStepsTertiary);
     std::vector<cv::Mat> frames1Tertiary(frames1Rect.end()-nStepsTertiary, frames1Rect.end());
     std::vector<cv::Mat> F1Primary = getDFTComponents(frames1Primary);
     cv::Mat up1Primary;
     cv::phase(F1Primary[2], -F1Primary[3], up1Primary);
     std::vector<cv::Mat> F1Secondary = getDFTComponents(frames1Secondary);
     cv::Mat up1Secondary;
     cv::phase(F1Secondary[2], -F1Secondary[3], up1Secondary);
     std::vector<cv::Mat> F1Tertiary = getDFTComponents(frames1Tertiary);
     cv::Mat up1Tertiary;
     cv::phase(F1Tertiary[2], -F1Tertiary[3], up1Tertiary);
+    cv::Mat up1EquivalentPS = up1Primary - up1Secondary;
+    up1EquivalentPS = cvtools::modulo(up1EquivalentPS, 2.0*pi);
-    cv::Mat up1Unwrap = unwrapWithCue(up1Secondary, up1Tertiary, nPeriodSecondary);
+    cv::Mat up1EquivalentST = up1Secondary - up1Tertiary;
+    up1EquivalentST = cvtools::modulo(up1EquivalentST, 2.0*pi);
+    cv::Mat up1Equivalent = up1EquivalentPS - up1EquivalentST;
+    up1Equivalent = cvtools::modulo(up1Equivalent, 2.0*pi);
-    cv::Mat up1 = unwrapWithCue(up1Primary, up1Unwrap, nPeriodPrimary);
+    cv::Mat up1 = unwrapWithCue(up1Primary, up1Equivalent, (float)screenCols/nPeriodsPrimary);
     up1 *= screenCols/(2.0*pi);
     cv::Mat amplitude1;
     cv::magnitude(F1Primary[2], -F1Primary[3], amplitude1);
+    #ifdef Q_DEBUG
-//cvtools::writeMat(up0Primary, "up0Primary.mat", "up0Primary");
+        cvtools::writeMat(up0Primary, "up0Primary.mat", "up0Primary");
-//cvtools::writeMat(up0Secondary, "up0Secondary.mat", "up0Secondary");
+        cvtools::writeMat(up0Secondary, "up0Secondary.mat", "up0Secondary");
-//cvtools::writeMat(up0Tertiary, "up0Tertiary.mat", "up0Tertiary");
+        cvtools::writeMat(up0Tertiary, "up0Tertiary.mat", "up0Tertiary");
+        cvtools::writeMat(up0EquivalentPS, "up0EquivalentPS.mat", "up0EquivalentPS");
-//cvtools::writeMat(up0Unwrap, "up0Unwrap.mat", "up0Unwrap");
+        cvtools::writeMat(up0EquivalentST, "up0EquivalentST.mat", "up0EquivalentST");
-//cvtools::writeMat(up0, "up0.mat", "up0");
+        cvtools::writeMat(up0, "up0.mat", "up0");
-//cvtools::writeMat(up1, "up1.mat", "up1");
+        cvtools::writeMat(up1, "up1.mat", "up1");
-//cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");
+        cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");
-//cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");
+        cvtools::writeMat(amplitude0, "amplitude0.mat", "amplitude0");
-//cvtools::writeMat(amplitude1, "amplitude1.mat", "amplitude1");
+        cvtools::writeMat(amplitude1, "amplitude1.mat", "amplitude1");
+    #endif
     // Color debayer and remap
     cv::Mat color0, color1;
     cv::cvtColor(frames0[0], color0, CV_BayerBG2RGB);
     cv::cvtColor(frames1[0], color1, CV_BayerBG2RGB);
+    #ifdef Q_DEBUG
-//cvtools::writeMat(color0, "color0.mat", "color0");
+        cvtools::writeMat(color0, "color0.mat", "color0");
-//cvtools::writeMat(color1, "color1.mat", "color1");
+        cvtools::writeMat(color1, "color1.mat", "color1");
+    #endif
     // Occlusion masks
     cv::Mat occlusion0, occlusion1;
     cv::subtract(frames0Rect[0], frames0Rect[1], occlusion0);
     occlusion0 = (occlusion0 > 5) & (occlusion0 < 250);
     cv::subtract(frames1Rect[0], frames1Rect[1], occlusion1);
     occlusion1 = (occlusion1 > 5) & (occlusion1 < 250);
-//    // Threshold on energy at primary frequency
+    #ifdef Q_DEBUG
-//    occlusion0 = occlusion0 & (amplitude0 > 5.0*nStepsPrimary);
-//    occlusion1 = occlusion1 & (amplitude1 > 5.0*nStepsPrimary);
-//cvtools::writeMat(occlusion0, "occlusion0.mat", "occlusion0");
-//cvtools::writeMat(occlusion1, "occlusion1.mat", "occlusion1");
-//    // Erode occlusion masks
+        // Erode occlusion masks
-//    cv::Mat strel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(5,5));
+        cv::Mat strel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(5,5));
-//    cv::erode(occlusion0, occlusion0, strel);
+        cv::erode(occlusion0, occlusion0, strel);
-//    cv::erode(occlusion1, occlusion1, strel);
+        cv::erode(occlusion1, occlusion1, strel);
+    #endif
     // Threshold on gradient of phase
     cv::Mat edges0;
     cv::Sobel(up0, edges0, -1, 1, 1, 5);
     occlusion0 = occlusion0 & (abs(edges0) < 150);
     cv::Mat edges1;
     cv::Sobel(up1, edges1, -1, 1, 1, 5);
     occlusion1 = occlusion1 & (abs(edges1) < 150);
+    #ifdef Q_DEBUG
-//cvtools::writeMat(edges0, "edges0.mat", "edges0");
+        cvtools::writeMat(edges0, "edges0.mat", "edges0");
-//cvtools::writeMat(edges1, "edges1.mat", "edges1");
+        cvtools::writeMat(edges1, "edges1.mat", "edges1");
+    #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)){
                     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::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);
+}

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(root)/src/algorithm/AlgorithmPhaseShiftThreeFreq.cpp – Rev 179 → 182