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import org.opencv.imgcodecs.Imgcodecs
import org.opencv.features2d.DescriptorExtractor
import org.opencv.features2d.Features2d
import org.opencv.core.MatOfKeyPoint
import org.opencv.core.Mat
import org.opencv.features2d.FeatureDetector
import org.opencv.features2d.DescriptorMatcher
import org.opencv.core.MatOfDMatch
import reflect._
/*
* Finds corresponding points between a pair of images using local descriptors.
* The correspondences are visualized in the image "scalaCorrespondences.png",
* which is written to disk.
*/
object ScalaCorrespondenceMatchingDemo {
def run() {
println(s"\nRunning ${classTag[this.type].toString.replace("$", "")}")
// Detects keypoints and extracts descriptors in a given image of type Mat.
def detectAndExtract(mat: Mat) = {
// A special container class for KeyPoint.
val keyPoints = new MatOfKeyPoint
// We're using the ORB detector.
val detector = FeatureDetector.create(FeatureDetector.ORB)
detector.detect(mat, keyPoints)
println(s"There were ${keyPoints.toArray.size} KeyPoints detected")
// Let's just use the best KeyPoints.
val sorted = keyPoints.toArray.sortBy(_.response).reverse.take(50)
// There isn't a constructor that takes Array[KeyPoint], so we unpack
// the array and use the constructor that can take any number of
// arguments.
val bestKeyPoints: MatOfKeyPoint = new MatOfKeyPoint(sorted: _*)
// We're using the ORB descriptor.
val extractor = DescriptorExtractor.create(DescriptorExtractor.ORB)
val descriptors = new Mat
extractor.compute(mat, bestKeyPoints, descriptors)
println(s"${descriptors.rows} descriptors were extracted, each with dimension ${descriptors.cols}")
(bestKeyPoints, descriptors)
}
// Load the images from the |resources| directory.
val leftImage = Imgcodecs.imread(getClass.getResource("/img1.png").getPath)
val rightImage = Imgcodecs.imread(getClass.getResource("/img2.png").getPath)
// Detect KeyPoints and extract descriptors.
val (leftKeyPoints, leftDescriptors) = detectAndExtract(leftImage)
val (rightKeyPoints, rightDescriptors) = detectAndExtract(rightImage)
// Match the descriptors.
val matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE)
// A special container class for DMatch.
val dmatches = new MatOfDMatch
// The backticks are because "match" is a keyword in Scala.
matcher.`match`(leftDescriptors, rightDescriptors, dmatches)
// Visualize the matches and save the visualization.
val correspondenceImage = new Mat
Features2d.drawMatches(leftImage, leftKeyPoints, rightImage, rightKeyPoints, dmatches, correspondenceImage)
val filename = "scalaCorrespondences.png"
println(s"Writing ${filename}")
assert(Imgcodecs.imwrite(filename, correspondenceImage))
}
}