Merge pull request #8458 from grundman:patch-2

modules/calib3d/src/circlesgrid.cpp

@@ -839,7 +839,11 @@ Mat CirclesGridFinder::rectifyGrid(Size detectedGridSize, const std::vector<Poin
   //Mat H = findHomography( Mat( corners ), Mat( dstPoints ) );
 
   if (H.empty())
+  {
       H = Mat::zeros(3, 3, CV_64FC1);
+      warpedKeypoints.clear();
+      return H;
+  }
 
   std::vector<Point2f> srcKeypoints;
   for (size_t i = 0; i < keypoints.size(); i++)