public static void FindMatch(Mat modelImage, Mat observedImage, out long matchTime, out VectorOfKeyPoint modelKeyPoints, out VectorOfKeyPoint observedKeyPoints, VectorOfVectorOfDMatch matches, out Mat mask, out Mat homography)
{
int k = 2;
double uniquenessThreshold = 0.8;
double hessianThresh = 300;
Stopwatch watch;
homography = null;
modelKeyPoints = new VectorOfKeyPoint();
observedKeyPoints = new VectorOfKeyPoint();
#if !__IOS__
if ( CudaInvoke.HasCuda)
{
CudaSURF surfCuda = new CudaSURF((float) hessianThresh);
using (GpuMat gpuModelImage = new GpuMat(modelImage))
//extract features from the object image
using (GpuMat gpuModelKeyPoints = surfCuda.DetectKeyPointsRaw(gpuModelImage, null))
using (GpuMat gpuModelDescriptors = surfCuda.ComputeDescriptorsRaw(gpuModelImage, null, gpuModelKeyPoints))
using (CudaBFMatcher matcher = new CudaBFMatcher(DistanceType.L2))
{
surfCuda.DownloadKeypoints(gpuModelKeyPoints, modelKeyPoints);
watch = Stopwatch.StartNew();
// extract features from the observed image
using (GpuMat gpuObservedImage = new GpuMat(observedImage))
using (GpuMat gpuObservedKeyPoints = surfCuda.DetectKeyPointsRaw(gpuObservedImage, null))
using (GpuMat gpuObservedDescriptors = surfCuda.ComputeDescriptorsRaw(gpuObservedImage, null, gpuObservedKeyPoints))
//using (GpuMat tmp = new GpuMat())
//using (Stream stream = new Stream())
{
matcher.KnnMatch(gpuObservedDescriptors, gpuModelDescriptors, matches, k);
surfCuda.DownloadKeypoints(gpuObservedKeyPoints, observedKeyPoints);
mask = new Mat(matches.Size, 1, DepthType.Cv8U, 1);
mask.SetTo(new MCvScalar(255));
Features2DToolbox.VoteForUniqueness(matches, uniquenessThreshold, mask);
int nonZeroCount = CvInvoke.CountNonZero(mask);
if (nonZeroCount >= 4)
{
nonZeroCount = Features2DToolbox.VoteForSizeAndOrientation(modelKeyPoints, observedKeyPoints,
matches, mask, 1.5, 20);
if (nonZeroCount >= 4)
homography = Features2DToolbox.GetHomographyMatrixFromMatchedFeatures(modelKeyPoints,
observedKeyPoints, matches, mask, 2);
}
}
watch.Stop();
}
}
else
#endif
{
using (UMat uModelImage = modelImage.ToUMat(AccessType.Read))
using (UMat uObservedImage = observedImage.ToUMat(AccessType.Read))
{
SURF surfCPU = new SURF(hessianThresh);
//extract features from the object image
UMat modelDescriptors = new UMat();
surfCPU.DetectAndCompute(uModelImage, null, modelKeyPoints, modelDescriptors, false);
watch = Stopwatch.StartNew();
// extract features from the observed image
UMat observedDescriptors = new UMat();
surfCPU.DetectAndCompute(uObservedImage, null, observedKeyPoints, observedDescriptors, false);
BFMatcher matcher = new BFMatcher(DistanceType.L2);
matcher.Add(modelDescriptors);
matcher.KnnMatch(observedDescriptors, matches, k, null);
mask = new Mat(matches.Size, 1, DepthType.Cv8U, 1);
mask.SetTo(new MCvScalar(255));
Features2DToolbox.VoteForUniqueness(matches, uniquenessThreshold, mask);
int nonZeroCount = CvInvoke.CountNonZero(mask);
if (nonZeroCount >= 4)
{
nonZeroCount = Features2DToolbox.VoteForSizeAndOrientation(modelKeyPoints, observedKeyPoints,
matches, mask, 1.5, 20);
if (nonZeroCount >= 4)
homography = Features2DToolbox.GetHomographyMatrixFromMatchedFeatures(modelKeyPoints,
observedKeyPoints, matches, mask, 2);
}
watch.Stop();
}
}
matchTime = watch.ElapsedMilliseconds;
}
public Mat Calculate(Bitmap referenceBitmap, Bitmap currentBitmap)
{
Mat homography;
using (var detector = new CudaSURF(threshold))
using (var model = new Image<Gray, byte>(referenceBitmap))
using (var observed = new Image<Gray, byte>(currentBitmap))
using (var modelMat = new GpuMat(model))
using (var modelKeyPointsRaw = detector.DetectKeyPointsRaw(modelMat))
using (var modelKeyPoints = new VectorOfKeyPoint())
using (var modelDescriptorsRaw = detector.ComputeDescriptorsRaw(modelMat, null, modelKeyPointsRaw))
using (var observedMat = new GpuMat(observed))
using (var observedKeyPointsRaw = detector.DetectKeyPointsRaw(observedMat))
using (var observedKeyPoints = new VectorOfKeyPoint())
using (var observedDescriptorsRaw = detector.ComputeDescriptorsRaw(observedMat, null, observedKeyPointsRaw))
using (
var matcher =
new CudaBFMatcher(DistanceType.L2))
using (var matches = new VectorOfVectorOfDMatch())
{
matcher.KnnMatch(observedDescriptorsRaw, modelDescriptorsRaw, matches, k);
detector.DownloadKeypoints(modelKeyPointsRaw, modelKeyPoints);
detector.DownloadKeypoints(observedKeyPointsRaw, observedKeyPoints);
homography = TryFindHomography(modelKeyPoints, observedKeyPoints, matches);
}
return homography;
}
public void TestBruteForceHammingDistance()
{
if (CudaInvoke.HasCuda)
{
Image<Gray, byte> box = new Image<Gray, byte>("box.png");
FastDetector fast = new FastDetector(100, true);
BriefDescriptorExtractor brief = new BriefDescriptorExtractor(32);
#region extract features from the object image
Stopwatch stopwatch = Stopwatch.StartNew();
VectorOfKeyPoint modelKeypoints = new VectorOfKeyPoint();
fast.DetectRaw(box, modelKeypoints);
Mat modelDescriptors = new Mat();
brief.Compute(box, modelKeypoints, modelDescriptors);
stopwatch.Stop();
Trace.WriteLine(String.Format("Time to extract feature from model: {0} milli-sec", stopwatch.ElapsedMilliseconds));
#endregion
Image<Gray, Byte> observedImage = new Image<Gray, byte>("box_in_scene.png");
#region extract features from the observed image
stopwatch.Reset(); stopwatch.Start();
VectorOfKeyPoint observedKeypoints = new VectorOfKeyPoint();
fast.DetectRaw(observedImage, observedKeypoints);
Mat observedDescriptors = new Mat();
brief.Compute(observedImage, observedKeypoints, observedDescriptors);
stopwatch.Stop();
Trace.WriteLine(String.Format("Time to extract feature from image: {0} milli-sec", stopwatch.ElapsedMilliseconds));
#endregion
Mat homography = null;
using (GpuMat<Byte> gpuModelDescriptors = new GpuMat<byte>(modelDescriptors)) //initialization of GPU code might took longer time.
{
stopwatch.Reset(); stopwatch.Start();
CudaBFMatcher hammingMatcher = new CudaBFMatcher(DistanceType.Hamming);
//BFMatcher hammingMatcher = new BFMatcher(BFMatcher.DistanceType.Hamming, modelDescriptors);
int k = 2;
Matrix<int> trainIdx = new Matrix<int>(observedKeypoints.Size, k);
Matrix<float> distance = new Matrix<float>(trainIdx.Size);
using (GpuMat<Byte> gpuObservedDescriptors = new GpuMat<byte>(observedDescriptors))
//using (GpuMat<int> gpuTrainIdx = new GpuMat<int>(trainIdx.Rows, trainIdx.Cols, 1, true))
//using (GpuMat<float> gpuDistance = new GpuMat<float>(distance.Rows, distance.Cols, 1, true))
using (VectorOfVectorOfDMatch matches = new VectorOfVectorOfDMatch())
{
Stopwatch w2 = Stopwatch.StartNew();
//hammingMatcher.KnnMatch(gpuObservedDescriptors, gpuModelDescriptors, matches, k);
hammingMatcher.KnnMatch(gpuObservedDescriptors, gpuModelDescriptors, matches, k, null, true);
w2.Stop();
Trace.WriteLine(String.Format("Time for feature matching (excluding data transfer): {0} milli-sec",
w2.ElapsedMilliseconds));
//gpuTrainIdx.Download(trainIdx);
//gpuDistance.Download(distance);
Mat mask = new Mat(distance.Rows, 1, DepthType.Cv8U, 1);
mask.SetTo(new MCvScalar(255));
Features2DToolbox.VoteForUniqueness(matches, 0.8, mask);
int nonZeroCount = CvInvoke.CountNonZero(mask);
if (nonZeroCount >= 4)
{
nonZeroCount = Features2DToolbox.VoteForSizeAndOrientation(modelKeypoints, observedKeypoints,
matches, mask, 1.5, 20);
if (nonZeroCount >= 4)
homography = Features2DToolbox.GetHomographyMatrixFromMatchedFeatures(modelKeypoints,
observedKeypoints, matches, mask, 2);
nonZeroCount = CvInvoke.CountNonZero(mask);
}
stopwatch.Stop();
Trace.WriteLine(String.Format("Time for feature matching (including data transfer): {0} milli-sec",
stopwatch.ElapsedMilliseconds));
}
}
if (homography != null)
{
Rectangle rect = box.ROI;
PointF[] pts = new PointF[] {
new PointF(rect.Left, rect.Bottom),
new PointF(rect.Right, rect.Bottom),
new PointF(rect.Right, rect.Top),
new PointF(rect.Left, rect.Top)};
PointF[] points = CvInvoke.PerspectiveTransform(pts, homography);
//homography.ProjectPoints(points);
//Merge the object image and the observed image into one big image for display
Image<Gray, Byte> res = box.ConcateVertical(observedImage);
for (int i = 0; i < points.Length; i++)
points[i].Y += box.Height;
res.DrawPolyline(Array.ConvertAll<PointF, Point>(points, Point.Round), true, new Gray(255.0), 5);
//ImageViewer.Show(res);
}
}
}