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import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.opencv.core.*;
import org.opencv.calib3d.Calib3d;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
class PerspectiveCorrectionRun {
void perspectiveCorrection (String[] args) {
String img1Path = args[0], img2Path = args[1];
Mat img1 = Imgcodecs.imread(img1Path);
Mat img2 = Imgcodecs.imread(img2Path);
//! [find-corners]
MatOfPoint2f corners1 = new MatOfPoint2f(), corners2 = new MatOfPoint2f();
boolean found1 = Calib3d.findChessboardCorners(img1, new Size(9, 6), corners1 );
boolean found2 = Calib3d.findChessboardCorners(img2, new Size(9, 6), corners2 );
//! [find-corners]
if (!found1 || !found2) {
System.out.println("Error, cannot find the chessboard corners in both images.");
System.exit(-1);
}
//! [estimate-homography]
Mat H = new Mat();
H = Calib3d.findHomography(corners1, corners2);
System.out.println(H.dump());
//! [estimate-homography]
//! [warp-chessboard]
Mat img1_warp = new Mat();
Imgproc.warpPerspective(img1, img1_warp, H, img1.size());
//! [warp-chessboard]
Mat img_draw_warp = new Mat();
List<Mat> list1 = new ArrayList<>(), list2 = new ArrayList<>() ;
list1.add(img2);
list1.add(img1_warp);
Core.hconcat(list1, img_draw_warp);
HighGui.imshow("Desired chessboard view / Warped source chessboard view", img_draw_warp);
//! [compute-transformed-corners]
Mat img_draw_matches = new Mat();
list2.add(img1);
list2.add(img2);
Core.hconcat(list2, img_draw_matches);
Point []corners1Arr = corners1.toArray();
for (int i = 0 ; i < corners1Arr.length; i++) {
Mat pt1 = new Mat(3, 1, CvType.CV_64FC1), pt2 = new Mat();
pt1.put(0, 0, corners1Arr[i].x, corners1Arr[i].y, 1 );
Core.gemm(H, pt1, 1, new Mat(), 0, pt2);
double[] data = pt2.get(2, 0);
Core.divide(pt2, new Scalar(data[0]), pt2);
double[] data1 =pt2.get(0, 0);
double[] data2 = pt2.get(1, 0);
Point end = new Point((int)(img1.cols()+ data1[0]), (int)data2[0]);
Imgproc.line(img_draw_matches, corners1Arr[i], end, RandomColor(), 2);
}
HighGui.imshow("Draw matches", img_draw_matches);
HighGui.waitKey(0);
//! [compute-transformed-corners]
System.exit(0);
}
Scalar RandomColor () {
Random rng = new Random();
int r = rng.nextInt(256);
int g = rng.nextInt(256);
int b = rng.nextInt(256);
return new Scalar(r, g, b);
}
}
public class PerspectiveCorrection {
public static void main (String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
new PerspectiveCorrectionRun().perspectiveCorrection(args);
}
}
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