Merge remote-tracking branch 'upstream/3.4' into merge-3.4

modules/features2d/src/bagofwords.cpp

@@ -177,6 +177,7 @@ void BOWImgDescriptorExtractor::compute( InputArray keypointDescriptors, OutputA
     CV_INSTRUMENT_REGION()
 
     CV_Assert( !vocabulary.empty() );
+    CV_Assert(!keypointDescriptors.empty());
 
     int clusterCount = descriptorSize(); // = vocabulary.rows
 

modules/features2d/src/blobdetector.cpp

@@ -264,6 +264,8 @@ void SimpleBlobDetectorImpl::findBlobs(InputArray _image, InputArray _binaryImag
             convexHull(Mat(contours[contourIdx]), hull);
             double area = contourArea(Mat(contours[contourIdx]));
             double hullArea = contourArea(Mat(hull));
+            if (fabs(hullArea) < DBL_EPSILON)
+                continue;
             double ratio = area / hullArea;
             if (ratio < params.minConvexity || ratio >= params.maxConvexity)
                 continue;
@@ -309,6 +311,7 @@ void SimpleBlobDetectorImpl::detect(InputArray image, std::vector<cv::KeyPoint>&
     CV_INSTRUMENT_REGION()
 
     keypoints.clear();
+    CV_Assert(params.minRepeatability != 0);
     Mat grayscaleImage;
     if (image.channels() == 3 || image.channels() == 4)
         cvtColor(image, grayscaleImage, COLOR_BGR2GRAY);

modules/features2d/src/brisk.cpp

@@ -506,6 +506,7 @@ BRISK_Impl::smoothedIntensity(const cv::Mat& image, const cv::Mat& integral, con
   // scaling:
   const int scaling = (int)(4194304.0 / area);
   const int scaling2 = int(float(scaling) * area / 1024.0);
+  CV_Assert(scaling2 != 0);
 
   // the integral image is larger:
   const int integralcols = imagecols + 1;
@@ -2238,6 +2239,7 @@ BriskLayer::value(const cv::Mat& mat, float xf, float yf, float scale_in) const
   // scaling:
   const int scaling = (int)(4194304.0f / area);
   const int scaling2 = (int)(float(scaling) * area / 1024.0f);
+  CV_Assert(scaling2 != 0);
 
   // calculate borders
   const float x_1 = xf - sigma_half;