java - DrawMatching between two images - 图像识别

Question

我试图显示两个图像之间的匹配关键点(一个是从我的相机捕获的，另一个是从数据库捕获的)

任何人都可以帮助我在我的代码中编写 DrawMatches 函数以显示 2 个图像之间的匹配线。

这是我的代码:

public final class ImageDetectionFilter{

// Flag draw target Image corner.
private boolean flagDraw ;

// The reference image (this detector's target).
private final Mat mReferenceImage;

// Features of the reference image.
private final MatOfKeyPoint mReferenceKeypoints = new MatOfKeyPoint();

// Descriptors of the reference image's features.
private final Mat mReferenceDescriptors = new Mat();

// The corner coordinates of the reference image, in pixels.
// CvType defines the color depth, number of channels, and
// channel layout in the image. Here, each point is represented
// by two 32-bit floats.
private final Mat mReferenceCorners = new Mat(4, 1, CvType.CV_32FC2);

// Features of the scene (the current frame).
private final MatOfKeyPoint mSceneKeypoints = new MatOfKeyPoint();
// Descriptors of the scene's features.
private final Mat mSceneDescriptors = new Mat();
// Tentative corner coordinates detected in the scene, in
// pixels.
private final Mat mCandidateSceneCorners = 
    new Mat(4, 1, CvType.CV_32FC2);
// Good corner coordinates detected in the scene, in pixels.
private final Mat mSceneCorners = new Mat(4, 1, CvType.CV_32FC2);
// The good detected corner coordinates, in pixels, as integers.
private final MatOfPoint mIntSceneCorners = new MatOfPoint();

// A grayscale version of the scene.
private final Mat mGraySrc = new Mat();
// Tentative matches of scene features and reference features.
private final MatOfDMatch mMatches = new MatOfDMatch();

// A feature detector, which finds features in images.
private final FeatureDetector mFeatureDetector = 
    FeatureDetector.create(FeatureDetector.ORB);
// A descriptor extractor, which creates descriptors of
// features.
private final DescriptorExtractor mDescriptorExtractor = 
    DescriptorExtractor.create(DescriptorExtractor.ORB);
// A descriptor matcher, which matches features based on their
// descriptors.
private final DescriptorMatcher mDescriptorMatcher = DescriptorMatcher
    .create(DescriptorMatcher.BRUTEFORCE_HAMMINGLUT);

// The color of the outline drawn around the detected image.
private final Scalar mLineColor = new Scalar(0, 255, 0);

public ImageDetectionFilter(final Context context,
    final int referenceImageResourceID) throws IOException {

// Load the reference image from the app's resources.
// It is loaded in BGR (blue, green, red) format.
mReferenceImage = Utils.loadResource(context, referenceImageResourceID,
        Imgcodecs.CV_LOAD_IMAGE_COLOR);

// Create grayscale and RGBA versions of the reference image.
final Mat referenceImageGray = new Mat();
Imgproc.cvtColor(mReferenceImage, referenceImageGray,
        Imgproc.COLOR_BGR2GRAY);

Imgproc.cvtColor(mReferenceImage, mReferenceImage,
        Imgproc.COLOR_BGR2RGBA);

// Store the reference image's corner coordinates, in pixels.
mReferenceCorners.put(0, 0, new double[] { 0.0, 0.0 });
mReferenceCorners.put(1, 0, 
        new double[] { referenceImageGray.cols(),0.0 });
mReferenceCorners.put(2, 0,
        new double[] { referenceImageGray.cols(),
        referenceImageGray.rows() });
mReferenceCorners.put(3, 0,
        new double[] { 0.0, referenceImageGray.rows() });

// Detect the reference features and compute their
// descriptors.
mFeatureDetector.detect(referenceImageGray, 
        mReferenceKeypoints);
mDescriptorExtractor.compute(referenceImageGray, 
        mReferenceKeypoints,mReferenceDescriptors);
}

public void apply(Mat src, Mat dst) {

// Convert the scene to grayscale.
Imgproc.cvtColor(src, mGraySrc, Imgproc.COLOR_RGBA2GRAY);

// Detect the same features, compute their descriptors,
// and match the scene descriptors to reference descriptors.
mFeatureDetector.detect(mGraySrc, mSceneKeypoints);
mDescriptorExtractor.compute(mGraySrc, mSceneKeypoints,
        mSceneDescriptors);
mDescriptorMatcher.match(mSceneDescriptors, 
        mReferenceDescriptors,mMatches);

findSceneCorners();

// If the corners have been found, draw an outline around the
// target image.
// Else, draw a thumbnail of the target image.
draw(src, dst);

}

private void findSceneCorners() {
flagDraw = false;

final List<DMatch> matchesList = mMatches.toList();

if (matchesList.size() < 4) {
    // There are too few matches to find the homography.
    return;
}

final List<KeyPoint> referenceKeypointsList = 
        mReferenceKeypoints.toList();
final List<KeyPoint> sceneKeypointsList = 
        mSceneKeypoints.toList();

// Calculate the max and min distances between keypoints.
double maxDist = 0.0;
double minDist = Double.MAX_VALUE;

for (final DMatch match : matchesList) {
    final double dist = match.distance;
    if (dist < minDist) {
        minDist = dist;
    }
    if (dist > maxDist) {
        maxDist = dist;
    }
}

// The thresholds for minDist are chosen subjectively
// based on testing. The unit is not related to pixel
// distances; it is related to the number of failed tests
// for similarity between the matched descriptors.
if (minDist > 50.0) {
    // The target is completely lost.
    // Discard any previously found corners.
    mSceneCorners.create(0, 0, mSceneCorners.type());
    return;
} else if (minDist > 25.0) {
    // The target is lost but maybe it is still close.
    // Keep any previously found corners.
    return;
}

// Identify "good" keypoints and on match distance.
final ArrayList<Point> goodReferencePointsList =
        new ArrayList<Point>();
final ArrayList<Point> goodScenePointsList =
        new ArrayList<Point>();
final double maxGoodMatchDist = 1.75 * minDist;
for (final DMatch match : matchesList) {
    if (match.distance < maxGoodMatchDist) {
        goodReferencePointsList.add(
                referenceKeypointsList.get(match.trainIdx).pt);
        goodScenePointsList
                .add(sceneKeypointsList.get(match.queryIdx).pt);
    }
}
if (goodReferencePointsList.size() < 4
        || goodScenePointsList.size() < 4) {
    // There are too few good points to find the homography.
    return;
}
// There are enough good points to find the homography.
// (Otherwise, the method would have already returned.)

// Convert the matched points to MatOfPoint2f format, as
// required by the Calib3d.findHomography function.
final MatOfPoint2f goodReferencePoints = new MatOfPoint2f();
goodReferencePoints.fromList(goodReferencePointsList);

final MatOfPoint2f goodScenePoints = new MatOfPoint2f();
goodScenePoints.fromList(goodScenePointsList);

// Find the homography.
final Mat homography = Calib3d.findHomography(
        goodReferencePoints,goodScenePoints);

// Use the homography to project the reference corner
// coordinates into scene coordinates.
Core.perspectiveTransform(mReferenceCorners,
        mCandidateSceneCorners,homography);

// Convert the scene corners to integer format, as required
// by the Imgproc.isContourConvex function.
mCandidateSceneCorners.convertTo(mIntSceneCorners, 
        CvType.CV_32S);

// Check whether the corners form a convex polygon. If not,
// (that is, if the corners form a concave polygon), the
// detection result is invalid because no real perspective can
// make the corners of a rectangular image look like a concave
// polygon!
if (Imgproc.isContourConvex(mIntSceneCorners)) {
    // The corners form a convex polygon, so record them as
    // valid scene corners.
    mCandidateSceneCorners.copyTo(mSceneCorners);
    flagDraw = true;
}

}

protected void draw(final Mat src, final Mat dst) {

if (dst != src) {
    src.copyTo(dst);
}

// Outline the found target in green.
Imgproc.line(dst, new Point(mSceneCorners.get(0, 0)), new Point(
        mSceneCorners.get(1, 0)), mLineColor, 4);
Imgproc.line(dst, new Point(mSceneCorners.get(1, 0)), new Point(
        mSceneCorners.get(2, 0)), mLineColor, 4);
Imgproc.line(dst, new Point(mSceneCorners.get(2, 0)), new Point(
        mSceneCorners.get(3, 0)), mLineColor, 4);
Imgproc.line(dst, new Point(mSceneCorners.get(3, 0)), new Point(
        mSceneCorners.get(0, 0)), mLineColor, 4);
}

public boolean getFlagDraw(){

return flagDraw;
}
}

Answer 1

我对 Java 不太熟悉，不确定这是否会有帮助，但我发布了一个示例，说明我如何使用 openCV 在 python 中实现这一点。也许这会帮助您作为指导。

(该示例改编自 this 网站，其中有您可能感兴趣的进一步解释)

在此示例中，我要在一组六只卡通动物中找到一只卡通动物的旋转版本。

基本上，您想使用训练和查询图像中的关键点调用 cv2.drawMatches() 并屏蔽不良匹配。我的代码的相关部分在最底部。

您的示例不是一个最小的代码示例，我没有完成所有的代码示例，但您似乎已经有了关键点并且应该准备好了吗？

import numpy as np
import cv2
from matplotlib import pyplot as plt

MIN_MATCH_COUNT = 4


img1 = cv2.imread('d:/one_animal_rotated.jpg',0)          # queryImage
img2 = cv2.imread('d:/many_animals.jpg',0) # trainImage

# Initiate SIFT detector
sift = cv2.xfeatures2d.SIFT_create(0,3,0)
# find the keypoints and descriptors with SIFT
kp1, des1 = sift.detectAndCompute(img1,None)
kp2, des2 = sift.detectAndCompute(img2,None)

#find matches using FLANN
FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks = 50)
flann = cv2.FlannBasedMatcher(index_params, search_params)
matches = flann.knnMatch(des1,des2,k=2)

#apply ratio test to find best matches (values from 0.7-1 made sense here)
good = []
for m,n in matches:
    if m.distance < 1*n.distance:
        good.append(m)

#find homography to transform the edges of the query image and draw them on the train image
#This is also used to mask all keypoints that aren't inside this box further below.
src_pts = np.float32([ kp1[m.queryIdx].pt for m in good]).reshape(-1,1,2)
dst_pts = np.float32([ kp2[m.trainIdx].pt for m in good]).reshape(-1,1,2)

M, mask = cv2.findHomography(src_pts, dst_pts, cv2.RANSAC,5.0)
matchesMask = mask.ravel().tolist()

h,w = img1.shape
pts = np.float32([ [0,0],[0,h-1],[w-1,h-1],[w-1,0] ]).reshape(-1,1,2)
dst = cv2.perspectiveTransform(pts,M)
img2 = cv2.polylines(img2,[np.int32(dst)],True,255,3, cv2.LINE_AA)

#draw the good matched key points
draw_params = dict(matchColor = (0,255,0), # draw matches in green color
                   singlePointColor = None,
                   matchesMask = matchesMask, # draw only inliers
                   flags = 2)

img3 = cv2.drawMatches(img1,kp1,img2,kp2,good,None,**draw_params)
plt.figure()
plt.imshow(img3, 'gray'),plt.show()