Merge pull request opencv#19498 from mattalvarado:fix_findcirclesgrid

* Properly handle empty centers in findCirclesGrid

* Address alalek comments. Add unit test to validate bugfix

* fix build warnings, remove unrelated comment

Author: mattalvarado

modules/calib3d/src/calibinit.cpp

@@ -2274,7 +2274,7 @@ bool findCirclesGrid2(InputArray _image, Size patternSize,
         }
     }
 
-    if (!H.empty())  // undone rectification
+    if (!centers.empty() && !H.empty())  // undone rectification
     {
         Mat orgPointsMat;
         transform(centers, orgPointsMat, H.inv());

modules/calib3d/test/test_chesscorners.cpp

@@ -541,5 +541,45 @@ TEST(Calib3d_AsymmetricCirclesPatternDetector, regression_18713)
     }
 }
 
+TEST(Calib3d_AsymmetricCirclesPatternDetector, regression_19498)
+{
+    float pts_[121][2] = {
+        { 84.7462f, 404.504f }, { 49.1586f, 404.092f }, { 12.3362f, 403.434f }, { 102.542f, 386.214f }, { 67.6042f, 385.475f },
+        { 31.4982f, 384.569f }, { 141.231f, 377.856f }, { 332.834f, 370.745f }, { 85.7663f, 367.261f }, { 50.346f, 366.051f },
+        { 13.7726f, 364.663f }, { 371.746f, 362.011f }, { 68.8543f, 347.883f }, { 32.9334f, 346.263f }, { 331.926f, 343.291f },
+        { 351.535f, 338.112f }, { 51.7951f, 328.247f }, { 15.4613f, 326.095f }, { 311.719f, 319.578f }, { 330.947f, 313.708f },
+        { 256.706f, 307.584f }, { 34.6834f, 308.167f }, { 291.085f, 295.429f }, { 17.4316f, 287.824f }, { 252.928f, 277.92f },
+        { 270.19f, 270.93f }, { 288.473f, 263.484f }, { 216.401f, 260.94f }, { 232.195f, 253.656f }, { 266.757f, 237.708f },
+        { 211.323f, 229.005f }, { 227.592f, 220.498f }, { 154.749f, 188.52f }, { 222.52f, 184.906f }, { 133.85f, 163.968f },
+        { 200.024f, 158.05f }, { 147.485f, 153.643f }, { 161.967f, 142.633f }, { 177.396f, 131.059f }, { 125.909f, 128.116f },
+        { 139.817f, 116.333f }, { 91.8639f, 114.454f }, { 104.343f, 102.542f }, { 117.635f, 89.9116f }, { 70.9465f, 89.4619f },
+        { 82.8524f, 76.7862f }, { 131.738f, 76.4741f }, { 95.5012f, 63.3351f }, { 109.034f, 49.0424f }, { 314.886f, 374.711f },
+        { 351.735f, 366.489f }, { 279.113f, 357.05f }, { 313.371f, 348.131f }, { 260.123f, 335.271f }, { 276.346f, 330.325f },
+        { 293.588f, 325.133f }, { 240.86f, 313.143f }, { 273.436f, 301.667f }, { 206.762f, 296.574f }, { 309.877f, 288.796f },
+        { 187.46f, 274.319f }, { 201.521f, 267.804f }, { 248.973f, 245.918f }, { 181.644f, 244.655f }, { 196.025f, 237.045f },
+        { 148.41f, 229.131f }, { 161.604f, 221.215f }, { 175.455f, 212.873f }, { 244.748f, 211.459f }, { 128.661f, 206.109f },
+        { 190.217f, 204.108f }, { 141.346f, 197.568f }, { 205.876f, 194.781f }, { 168.937f, 178.948f }, { 121.006f, 173.714f },
+        { 183.998f, 168.806f }, { 88.9095f, 159.731f }, { 100.559f, 149.867f }, { 58.553f, 146.47f }, { 112.849f, 139.302f },
+        { 80.0968f, 125.74f }, { 39.24f, 123.671f }, { 154.582f, 103.85f }, { 59.7699f, 101.49f }, { 266.334f, 385.387f },
+        { 234.053f, 368.718f }, { 263.347f, 361.184f }, { 244.763f, 339.958f }, { 198.16f, 328.214f }, { 211.675f, 323.407f },
+        { 225.905f, 318.426f }, { 192.98f, 302.119f }, { 221.267f, 290.693f }, { 161.437f, 286.46f }, { 236.656f, 284.476f },
+        { 168.023f, 251.799f }, { 105.385f, 221.988f }, { 116.724f, 214.25f }, { 97.2959f, 191.81f }, { 108.89f, 183.05f },
+        { 77.9896f, 169.242f }, { 48.6763f, 156.088f }, { 68.9635f, 136.415f }, { 29.8484f, 133.886f }, { 49.1966f, 112.826f },
+        { 113.059f, 29.003f }, { 251.698f, 388.562f }, { 281.689f, 381.929f }, { 297.875f, 378.518f }, { 248.376f, 365.025f },
+        { 295.791f, 352.763f }, { 216.176f, 348.586f }, { 230.143f, 344.443f }, { 179.89f, 307.457f }, { 174.083f, 280.51f },
+        { 142.867f, 265.085f }, { 155.127f, 258.692f }, { 124.187f, 243.661f }, { 136.01f, 236.553f }, { 86.4651f, 200.13f },
+        { 67.5711f, 178.221f }
+    };
+
+    Mat candidates(121, 1, CV_32FC2, (void*)pts_);
+    Size patternSize(13, 8);
+
+    std::vector< Point2f > result;
+    bool res = false;
+
+    EXPECT_NO_THROW(res = findCirclesGrid(candidates, patternSize, result, CALIB_CB_SYMMETRIC_GRID, Ptr<FeatureDetector>()/*blobDetector=NULL*/));
+    EXPECT_FALSE(res);
+}
+
 }} // namespace
 /* End of file. */