OpenCV4入门118:特征综合

索引地址:系列索引

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#include "opencv2/opencv.hpp"

using namespace std;
using namespace cv;

int main() {
double matchThresh;

// ***** Read images
Mat object = imread("TestObject.png");
Mat scene = imread("TestScene.png");

// ***** Create the algorithm accordingly
int algorithm = 1;
Ptr<Feature2D> detector;
switch (algorithm) {
case 1:
detector = BRISK::create();
matchThresh = 350;
break;

case 2:
detector = KAZE::create();
matchThresh = 0.1;
break;

case 3:
detector = AKAZE::create();
matchThresh = 250;
break;
}

// ***** Detect features
vector<KeyPoint> objKPs, scnKPs;
detector->detect(object, objKPs);
detector->detect(scene, scnKPs);

// ***** Extract descriptors
Mat objDesc, scnDesc;
detector->compute(object, objKPs, objDesc);
detector->compute(scene, scnKPs, scnDesc);

// ***** Match descriptors
Ptr<BFMatcher> matcher = BFMatcher::create();
vector<DMatch> matches;
matcher->match(objDesc, scnDesc, matches);

// ***** Remove "bad" matches
vector<DMatch> goodMatches;
for (int i = 0; i < objDesc.rows; i++) {
if (matches[ i ].distance < matchThresh)
goodMatches.push_back(matches[ i ]);
}

if (goodMatches.size() > 0) {
cout << "Found " << goodMatches.size() << " good matches.";
} else {
cout << "Didn't find a single good match. Quitting!";
return -1;
}

// ***** Draw matches
Mat result;
drawMatches(object, objKPs, scene, scnKPs, goodMatches, result,
Scalar(0, 255, 0), // green for matched
Scalar::all(-1), // unmatched color (default)
vector<char>(), // empty mask
DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);

// ***** Find the homography change between object and scene
vector<Point2f> goodP1, goodP2;
for (int i = 0; i < goodMatches.size(); i++) {
goodP1.push_back(objKPs[ goodMatches[ i ].queryIdx ].pt);
goodP2.push_back(scnKPs[ goodMatches[ i ].trainIdx ].pt);
}
Mat homoChange = findHomography(goodP1, goodP2);

// ***** Apply perpective change to find the result points
vector<Point2f> corners1(4), corners2(4);
corners1[ 0 ] = Point2f(0, 0);
corners1[ 1 ] = Point2f(object.cols - 1, 0);
corners1[ 2 ] = Point2f(object.cols - 1, object.rows - 1);
corners1[ 3 ] = Point2f(0, object.rows - 1);
perspectiveTransform(corners1, corners2, homoChange);

// ***** Correct the coordinates to fir the drawMatches result image
for (int i = 0; i < 4; i++)
corners2[ i ].x += object.cols;

// ***** Draw the bounding lines
line(result, corners2[ 0 ], corners2[ 1 ], Scalar::all(255), 2);
line(result, corners2[ 1 ], corners2[ 2 ], Scalar::all(255), 2);
line(result, corners2[ 2 ], corners2[ 3 ], Scalar::all(255), 2);
line(result, corners2[ 3 ], corners2[ 0 ], Scalar::all(255), 2);

imshow("Result", result);
waitKey();

return 0;
}

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