fix search for one contour in _filterTooCloseCandidates() + add regression_3192 test

Author: AleksandrPanov

modules/aruco/src/aruco.cpp

@@ -284,6 +284,7 @@ static void _filterTooCloseCandidates(const vector< vector< Point2f > > &candida
     candGroup.resize(candidatesIn.size(), -1);
     vector< vector<unsigned int> > groupedCandidates;
     for(unsigned int i = 0; i < candidatesIn.size(); i++) {
+        bool isSingleContour = true;
         for(unsigned int j = i + 1; j < candidatesIn.size(); j++) {
 
             int minimumPerimeter = min((int)contoursIn[i].size(), (int)contoursIn[j].size() );
@@ -304,6 +305,7 @@ static void _filterTooCloseCandidates(const vector< vector< Point2f > > &candida
                 // if mean square distance is too low, remove the smaller one of the two markers
                 double minMarkerDistancePixels = double(minimumPerimeter) * minMarkerDistanceRate;
                 if(distSq < minMarkerDistancePixels * minMarkerDistancePixels) {
+                    isSingleContour = false;
                     // i and j are not related to a group
                     if(candGroup[i]<0 && candGroup[j]<0){
                         // mark candidates with their corresponding group number
@@ -334,6 +336,14 @@ static void _filterTooCloseCandidates(const vector< vector< Point2f > > &candida
                 }
             }
         }
+        if (isSingleContour && candGroup[i] < 0)
+        {
+            candGroup[i] = (int)groupedCandidates.size();
+            vector<unsigned int> grouped;
+            grouped.push_back(i);
+            grouped.push_back(i);
+            groupedCandidates.push_back( grouped );
+        }
     }
 
     // save possible candidates

modules/aruco/test/test_arucodetection.cpp

@@ -594,7 +594,7 @@ TEST(CV_ArucoTutorial, can_find_gboriginal)
     string imgPath = cvtest::findDataFile("gboriginal.png", false);
     Mat image = imread(imgPath);
     string dictPath = cvtest::findDataFile("tutorial_dict.yml", false);
-    cv::Ptr<cv::aruco::Dictionary> dictionary;
+    Ptr<aruco::Dictionary> dictionary = makePtr<aruco::Dictionary>();
 
     FileStorage fs(dictPath, FileStorage::READ);
     dictionary->aruco::Dictionary::readDictionary(fs.root()); // set marker from tutorial_dict.yml
@@ -644,4 +644,20 @@ TEST(CV_ArucoTutorial, can_find_gboriginal)
     }
 }
 
+TEST(CV_ArucoTutorial, regression_3192)
+{
+    Ptr<aruco::Dictionary> dictionary = aruco::getPredefinedDictionary(aruco::DICT_4X4_50);
+    Ptr<aruco::DetectorParameters> detectorParams = aruco::DetectorParameters::create();
+    //detectorParams->cornerRefinementMethod = aruco::CORNER_REFINE_APRILTAG;
+    vector< int > markerIds;
+    vector<vector<Point2f> > markerCorners;
+
+    string imgPath = cvtest::findDataFile("aruco/regression_3192.png", true);
+    Mat image = imread(imgPath);
+
+    aruco::detectMarkers(image, dictionary, markerCorners, markerIds, detectorParams);
+    ASSERT_EQ(2ull, markerIds.size());
+
+}
+
 }} // namespace

modules/aruco/test/test_charucodetection.cpp

@@ -695,7 +695,7 @@ TEST(CV_ArucoTutorial, can_find_diamondmarkers)
     Mat image = imread(imgPath);
 
     string dictPath = cvtest::findDataFile("tutorial_dict.yml", false);
-    Ptr<cv::aruco::Dictionary> dictionary;
+    Ptr<aruco::Dictionary> dictionary = makePtr<aruco::Dictionary>();
     FileStorage fs(dictPath, FileStorage::READ);
     dictionary->aruco::Dictionary::readDictionary(fs.root()); // set marker from tutorial_dict.yml
 
@@ -745,15 +745,16 @@ TEST(Charuco, issue_14014)
     ASSERT_EQ(corners.size(), 19ull);
     EXPECT_EQ(Size(4, 1), corners[0].size()); // check dimension of detected corners
 
-    ASSERT_EQ(rejectedPoints.size(), 21ull);
+    size_t numRejPoints = rejectedPoints.size();
+    ASSERT_TRUE(numRejPoints > 0ull);
     EXPECT_EQ(Size(4, 1), rejectedPoints[0].size()); // check dimension of detected corners
 
     aruco::refineDetectedMarkers(img, board, corners, ids, rejectedPoints);
 
     ASSERT_EQ(corners.size(), 20ull);
     EXPECT_EQ(Size(4, 1), corners[0].size()); // check dimension of rejected corners after successfully refine
 
-    ASSERT_EQ(rejectedPoints.size(), 20ull);
+    ASSERT_EQ(rejectedPoints.size() + 1, numRejPoints);
     EXPECT_EQ(Size(4, 1), rejectedPoints[0].size()); // check dimension of rejected corners after successfully refine
 }