From e675684c81ac8b0094b8414960473a83fd5454c2 Mon Sep 17 00:00:00 2001
From: Vladislav Vinogradov <vlad.vinogradov@itseez.com>
Date: Tue, 24 Sep 2013 14:45:13 +0400
Subject: [PATCH] fix bug #3277 (findCirclesGrid failures):

findHomagraphy can return empty Mat in master branch
---
 modules/calib3d/src/circlesgrid.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/modules/calib3d/src/circlesgrid.cpp b/modules/calib3d/src/circlesgrid.cpp
index 969611fbc6..f44807e476 100644
--- a/modules/calib3d/src/circlesgrid.cpp
+++ b/modules/calib3d/src/circlesgrid.cpp
@@ -836,6 +836,9 @@ Mat CirclesGridFinder::rectifyGrid(Size detectedGridSize, const std::vector<Poin
   Mat H = findHomography(Mat(centers), Mat(dstPoints), RANSAC);
   //Mat H = findHomography( Mat( corners ), Mat( dstPoints ) );
 
+  if (H.empty())
+      H = Mat::zeros(3, 3, CV_64FC1);
+
   std::vector<Point2f> srcKeypoints;
   for (size_t i = 0; i < keypoints.size(); i++)
   {