private extern static void CvSURFDetectorComputeDescriptors(
ref MCvSURFParams detector,
IntPtr image,
IntPtr mask,
IntPtr keypoints,
IntPtr descriptors);
private extern static IntPtr CvSURFGetDescriptorExtractor(ref MCvSURFParams detector);
private extern static IntPtr CvSURFGetFeatureDetector(ref MCvSURFParams detector);
/// <summary>
/// Create an OpenCL SURF detector using the default parameters
/// </summary>
/// <param name="detector">The surf detector where the parameters will be borrow from</param>
/// <param name="FeaturesRatio">Max features = featuresRatio * img.size().srea(). Use 0.01 for default</param>
public OclSURFDetector(MCvSURFParams detector, float FeaturesRatio)
: this((float)detector.HessianThreshold, detector.NOctaves, detector.NOctaveLayers, (detector.Extended != 0), 0.01f, (detector.Upright != 0))
{
}
static void Run()
{
MCvSURFParams surfParam = new MCvSURFParams(500, false);
Image <Gray, Byte> modelImage = new Image <Gray, byte>("box.png");
//extract features from the object image
SURFFeature[] modelFeatures = modelImage.ExtractSURF(ref surfParam);
//Create a SURF Tracker
SURFTracker tracker = new SURFTracker(modelFeatures);
Image <Gray, Byte> observedImage = new Image <Gray, byte>("box_in_scene.png");
Stopwatch watch = Stopwatch.StartNew();
// extract features from the observed image
SURFFeature[] imageFeatures = observedImage.ExtractSURF(ref surfParam);
SURFTracker.MatchedSURFFeature[] matchedFeatures = tracker.MatchFeature(imageFeatures, 2, 20);
matchedFeatures = SURFTracker.VoteForUniqueness(matchedFeatures, 0.8);
matchedFeatures = SURFTracker.VoteForSizeAndOrientation(matchedFeatures, 1.5, 20);
HomographyMatrix homography = SURFTracker.GetHomographyMatrixFromMatchedFeatures(matchedFeatures);
watch.Stop();
//Merge the object image and the observed image into one image for display
Image <Gray, Byte> res = modelImage.ConcateVertical(observedImage);
#region draw lines between the matched features
foreach (SURFTracker.MatchedSURFFeature matchedFeature in matchedFeatures)
{
PointF p = matchedFeature.ObservedFeature.Point.pt;
p.Y += modelImage.Height;
res.Draw(new LineSegment2DF(matchedFeature.SimilarFeatures[0].Feature.Point.pt, p), new Gray(0), 1);
}
#endregion
#region draw the project region on the image
if (homography != null)
{ //draw a rectangle along the projected model
Rectangle rect = modelImage.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)
};
homography.ProjectPoints(pts);
for (int i = 0; i < pts.Length; i++)
{
pts[i].Y += modelImage.Height;
}
res.DrawPolyline(Array.ConvertAll <PointF, Point>(pts, Point.Round), true, new Gray(255.0), 5);
}
#endregion
ImageViewer.Show(res, String.Format("Matched in {0} milliseconds", watch.ElapsedMilliseconds));
}
/// <summary>
/// Create a SURF detector with the specific surfParameters
/// </summary>
/// <param name="surfParams">The surf parameters</param>
public SURFDetector(MCvSURFParams surfParams)
{
_surfParams = surfParams;
_ptr = CvInvoke.CvSURFDetectorCreate(ref surfParams, ref _featureDetectorPtr, ref _descriptorExtractorPtr);
}