added the filtering of keypoints having zero size (#877)

modules/features2d/include/opencv2/features2d/features2d.hpp

@@ -263,6 +263,26 @@ CV_EXPORTS void write(FileStorage& fs, const string& name, const vector<KeyPoint
 //! reads vector of keypoints from the specified file storage node
 CV_EXPORTS void read(const FileNode& node, CV_OUT vector<KeyPoint>& keypoints);    
 
+/*
+ * A class filters a vector of keypoints.
+ * Because now it is difficult to provide a convenient interface for all usage scenarios of the keypoints filter class,
+ * it has only 2 needed by now static methods.
+ */
+class CV_EXPORTS KeyPointsFilter
+{
+public:
+    KeyPointsFilter(){}
+
+    /*
+     * Remove keypoints within borderPixels of an image edge.
+     */
+    static void runByImageBorder( vector<KeyPoint>& keypoints, Size imageSize, int borderSize );
+    /*
+     * Remove keypoints of sizes out of range.
+     */
+    static void runByKeypointSize( vector<KeyPoint>& keypoints, float minSize, float maxSize=std::numeric_limits<float>::max() );
+};
+
 /*!
  SIFT implementation.
  
@@ -1625,12 +1645,6 @@ public:
 
 protected:
     virtual void computeImpl( const Mat& image, vector<KeyPoint>& keypoints, Mat& descriptors ) const = 0;
-
-    /*
-     * Remove keypoints within borderPixels of an image edge.
-     */
-    static void removeBorderKeypoints( vector<KeyPoint>& keypoints,
-                                       Size imageSize, int borderSize );
 };
 
 /*
@@ -1715,7 +1729,7 @@ void CalonderDescriptorExtractor<T>::computeImpl( const cv::Mat& image,
                                               cv::Mat& descriptors) const
 {
     // Cannot compute descriptors for keypoints on the image border.
-    removeBorderKeypoints(keypoints, image.size(), BORDER_SIZE);
+    KeyPointsFilter::runByImageBorder(keypoints, image.size(), BORDER_SIZE);
 
     /// @todo Check 16-byte aligned
     descriptors.create(keypoints.size(), classifier_.classes(), cv::DataType<T>::type);

modules/features2d/src/brief.cpp

@@ -208,7 +208,7 @@ void BriefDescriptorExtractor::computeImpl(const Mat& image, std::vector<KeyPoin
     integral( grayImage, sum, CV_32S);
 
     //Remove keypoints very close to the border
-    removeBorderKeypoints(keypoints, image.size(), PATCH_SIZE/2 + KERNEL_SIZE/2);
+    KeyPointsFilter::runByImageBorder(keypoints, image.size(), PATCH_SIZE/2 + KERNEL_SIZE/2);
 
     descriptors = Mat::zeros((int)keypoints.size(), bytes_, CV_8U);
     test_fn_(sum, keypoints, descriptors);

modules/features2d/src/descriptors.cpp

@@ -52,30 +52,20 @@ namespace cv
 /*
  *   DescriptorExtractor
  */
-struct RoiPredicate
-{
-    RoiPredicate( const Rect& _r ) : r(_r)
-    {}
-
-    bool operator()( const KeyPoint& keyPt ) const
-    {
-        return !r.contains( keyPt.pt );
-    }
-
-    Rect r;
-};
-
 DescriptorExtractor::~DescriptorExtractor()
 {}
 
 void DescriptorExtractor::compute( const Mat& image, vector<KeyPoint>& keypoints, Mat& descriptors ) const
 {    
     if( image.empty() || keypoints.empty() )
+    {
+        descriptors.release();
         return;
+    }
+
 
-    // Check keypoints are in image. Do filter bad points here?
-    //for( size_t i = 0; i < keypoints.size(); i++ )
-    //  CV_Assert( Rect(0,0, image.cols, image.rows).contains(keypoints[i].pt) );
+    KeyPointsFilter::runByImageBorder( keypoints, image.size(), 0 );
+    KeyPointsFilter::runByKeypointSize( keypoints, std::numeric_limits<float>::epsilon() );
 
     computeImpl( image, keypoints, descriptors );
 }
@@ -99,18 +89,6 @@ bool DescriptorExtractor::empty() const
     return false;
 }
 
-void DescriptorExtractor::removeBorderKeypoints( vector<KeyPoint>& keypoints,
-                                                 Size imageSize, int borderSize )
-{
-    if( borderSize > 0)
-    {
-        keypoints.erase( remove_if(keypoints.begin(), keypoints.end(),
-                                   RoiPredicate(Rect(Point(borderSize, borderSize),
-                                                     Point(imageSize.width - borderSize, imageSize.height - borderSize)))),
-                         keypoints.end() );
-    }
-}
-
 Ptr<DescriptorExtractor> DescriptorExtractor::create(const string& descriptorExtractorType)
 {
     DescriptorExtractor* de = 0;

modules/features2d/src/keypoint.cpp

@@ -152,4 +152,52 @@ float KeyPoint::overlap( const KeyPoint& kp1, const KeyPoint& kp2 )
     return ovrl;
 }
 
+struct RoiPredicate
+{
+    RoiPredicate( const Rect& _r ) : r(_r)
+    {}
+
+    bool operator()( const KeyPoint& keyPt ) const
+    {
+        return !r.contains( keyPt.pt );
+    }
+
+    Rect r;
+};
+
+void KeyPointsFilter::runByImageBorder( vector<KeyPoint>& keypoints, Size imageSize, int borderSize )
+{
+    if( borderSize > 0)
+    {
+        keypoints.erase( remove_if(keypoints.begin(), keypoints.end(),
+                                   RoiPredicate(Rect(Point(borderSize, borderSize),
+                                                     Point(imageSize.width - borderSize, imageSize.height - borderSize)))),
+                         keypoints.end() );
+    }
+}
+
+struct SizePredicate
+{
+    SizePredicate( float _minSize, float _maxSize ) : minSize(_minSize), maxSize(_maxSize)
+    {}
+
+    bool operator()( const KeyPoint& keyPt ) const
+    {
+        float size = keyPt.size;
+        return (size < minSize) || (size > maxSize);
+    }
+
+    float minSize, maxSize;
+};
+
+void KeyPointsFilter::runByKeypointSize( vector<KeyPoint>& keypoints, float minSize, float maxSize )
+{
+    CV_Assert( minSize >= 0 );
+    CV_Assert( maxSize >= 0);
+    CV_Assert( minSize <= maxSize );
+
+    keypoints.erase( remove_if(keypoints.begin(), keypoints.end(), SizePredicate(minSize, maxSize)),
+                     keypoints.end() );
+}
+
 }

modules/features2d/src/matchers.cpp

@@ -736,10 +736,20 @@ GenericDescriptorMatcher::GenericDescriptorMatcher()
 GenericDescriptorMatcher::~GenericDescriptorMatcher()
 {}
 
-void GenericDescriptorMatcher::add( const vector<Mat>& imgCollection,
-                                    vector<vector<KeyPoint> >& pointCollection )
+void GenericDescriptorMatcher::add( const vector<Mat>& images,
+                                    vector<vector<KeyPoint> >& keypoints )
 {
-    trainPointCollection.add( imgCollection, pointCollection );
+    CV_Assert( !images.empty() );
+    CV_Assert( images.size() == keypoints.size() );
+
+    for( size_t i = 0; i < images.size(); i++ )
+    {
+        CV_Assert( !images[i].empty() );
+        KeyPointsFilter::runByImageBorder( keypoints[i], images[i].size(), 0 );
+        KeyPointsFilter::runByKeypointSize( keypoints[i], std::numeric_limits<float>::epsilon() );
+    }
+
+    trainPointCollection.add( images, keypoints );
 }
 
 const vector<Mat>& GenericDescriptorMatcher::getTrainImages() const
@@ -827,6 +837,14 @@ void GenericDescriptorMatcher::knnMatch( const Mat& queryImage, vector<KeyPoint>
                                          vector<vector<DMatch> >& matches, int knn,
                                          const vector<Mat>& masks, bool compactResult )
 {
+    matches.clear();
+
+    if( queryImage.empty() || queryKeypoints.empty() )
+        return;
+
+    KeyPointsFilter::runByImageBorder( queryKeypoints, queryImage.size(), 0 );
+    KeyPointsFilter::runByKeypointSize( queryKeypoints, std::numeric_limits<float>::epsilon() );
+    
     train();
     knnMatchImpl( queryImage, queryKeypoints, matches, knn, masks, compactResult );
 }
@@ -835,6 +853,14 @@ void GenericDescriptorMatcher::radiusMatch( const Mat& queryImage, vector<KeyPoi
                                             vector<vector<DMatch> >& matches, float maxDistance,
                                             const vector<Mat>& masks, bool compactResult )
 {
+    matches.clear();
+
+    if( queryImage.empty() || queryKeypoints.empty() )
+        return;
+
+    KeyPointsFilter::runByImageBorder( queryKeypoints, queryImage.size(), 0 );
+    KeyPointsFilter::runByKeypointSize( queryKeypoints, std::numeric_limits<float>::epsilon() );
+	
     train();
     radiusMatchImpl( queryImage, queryKeypoints, matches, maxDistance, masks, compactResult );
 }