Hello I am currently trying to execute Feature Matching with FLANN from OpenCV in Java.
Here is code of this Tutorial: https://docs.opencv.org/master/d5/d6f/tutorial_feature_flann_matcher.html
My Project was created with "Java with Ant"
I have added the following dependencies
aistcv-4.5.3.jar, opencv-453.jar and opencv_java453.dll to Project folder.
When I try to run this code an error message comes up.
run:
Exception in thread "main" java.lang.UnsatisfiedLinkError: org/opencv/xfeatures2d/SURF.create_0(DIIZZ)J
at org.opencv.xfeatures2d.SURF.create(SURF.java:92)
at surfflannmatchingdemo.SURFFLANNMatching.run(SURFFLANNMatchingDemo.java:43)
at surfflannmatchingdemo.SURFFLANNMatchingDemo.main(SURFFLANNMatchingDemo.java:80)
C:\Users\Juergen\AppData\Local\NetBeans\Cache\12.5\executor-snippets\run.xml:111: The following error occurred while executing this line:
C:\Users\Juergen\AppData\Local\NetBeans\Cache\12.5\executor-snippets\run.xml:68: Java returned: 1
BUILD FAILED (total time: 0 seconds)
What am I doing wrong?
CodePudding user response:
SURF is still patented.
you can only use it IF you build from src with OPENCV_ENABLE_NONFREE=ON.
(you also probably dont have any contrib modules if it is the prebuilt jar file from SF)
try to replace it with SIFT
CodePudding user response:
OpenCV Java Feature Matching with FLANN
If any body have the same trouble like me, here is the Solution.
import java.util.ArrayList;
import java.util.List;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.DMatch;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.core.MatOfDMatch;
import org.opencv.core.MatOfKeyPoint;
import org.opencv.core.Scalar;
import org.opencv.features2d.DescriptorMatcher;
import org.opencv.features2d.Features2d;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.xfeatures2d.SURF;
import org.opencv.features2d.SIFT;
class SURFFLANNMatching {
public void run(String[] args) {
String filename1 = args.length > 1 ? args[0] : "foto_111.png";
String filename2 = args.length > 1 ? args[1] : "foto_222.png";
Mat img1 = Imgcodecs.imread(filename1, Imgcodecs.IMREAD_GRAYSCALE);
Mat img2 = Imgcodecs.imread(filename2, Imgcodecs.IMREAD_GRAYSCALE);
if (img1.empty() || img2.empty()) {
System.err.println("Cannot read images!");
System.exit(0);
}
//-- Step 1: Detect the keypoints using SURF Detector, compute the descriptors
double contrastThreshold = 0.03;
double edgeThreshold = 2.0;
double sigma = 1.0;
int nOctaveLayers = 3;
int hessianThreshold = 400;
boolean extended = false;
boolean upright = false;
// make error SURF detector = SURF.create(hessianThreshold, nOctaves, nOctaveLayers, extended, upright);
// Solution start.
SIFT detector = SIFT.create(hessianThreshold, nOctaveLayers, contrastThreshold, edgeThreshold, sigma);
// Solution stop.
MatOfKeyPoint keypoints1 = new MatOfKeyPoint(), keypoints2 = new MatOfKeyPoint();
Mat descriptors1 = new Mat(), descriptors2 = new Mat();
detector.detectAndCompute(img1, new Mat(), keypoints1, descriptors1);
detector.detectAndCompute(img2, new Mat(), keypoints2, descriptors2);
//-- Step 2: Matching descriptor vectors with a FLANN based matcher
// Since SURF is a floating-point descriptor NORM_L2 is used
DescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.FLANNBASED);
List<MatOfDMatch> knnMatches = new ArrayList<>();
matcher.knnMatch(descriptors1, descriptors2, knnMatches, 2);
//-- Filter matches using the Lowe's ratio test
float ratioThresh = 0.7f;
List<DMatch> listOfGoodMatches = new ArrayList<>();
for (int i = 0; i < knnMatches.size(); i ) {
if (knnMatches.get(i).rows() > 1) {
DMatch[] matches = knnMatches.get(i).toArray();
if (matches[0].distance < ratioThresh * matches[1].distance) {
listOfGoodMatches.add(matches[0]);
}
}
}
MatOfDMatch goodMatches = new MatOfDMatch();
goodMatches.fromList(listOfGoodMatches);
//-- Draw matches
Mat imgMatches = new Mat();
Features2d.drawMatches(img1, keypoints1, img2, keypoints2, goodMatches, imgMatches, Scalar.all(-1),
Scalar.all(-1), new MatOfByte(), Features2d.DrawMatchesFlags_NOT_DRAW_SINGLE_POINTS);
//-- Show detected matches
HighGui.imshow("Good Matches", imgMatches);
HighGui.waitKey(0);
System.exit(0);
}
}
public class SURFFLANNMatchingDemo {
public static void main(String[] args) {
// Load the native OpenCV library
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
new SURFFLANNMatching().run(args);
}
}