Add check for all zero moments. If one of the shapes is empty, the match would…

Add check for all zero moments. If one of the shapes is empty, the match would return zero distance between the shapes even when the other one had content. It now returns DBL_MAX if no moments had value.

modules/imgproc/src/matchcontours.cpp

@@ -50,6 +50,7 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
     double eps = 1.e-5;
     double mmm;
     double result = 0;
+    bool anyResults = false;
 
     HuMoments( moments(contour1), ma );
     HuMoments( moments(contour2), mb );
@@ -80,6 +81,7 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
                 ama = 1. / (sma * log10( ama ));
                 amb = 1. / (smb * log10( amb ));
                 result += fabs( -ama + amb );
+                anyResults = true;
             }
         }
         break;
@@ -108,6 +110,7 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
                 ama = sma * log10( ama );
                 amb = smb * log10( amb );
                 result += fabs( -ama + amb );
+                anyResults = true;
             }
         }
         break;
@@ -138,6 +141,7 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
                 mmm = fabs( (ama - amb) / ama );
                 if( result < mmm )
                     result = mmm;
+                anyResults = true;
             }
         }
         break;
@@ -145,6 +149,9 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
         CV_Error( CV_StsBadArg, "Unknown comparison method" );
     }
 
+    if (!anyResults)
+        result = DBL_MAX;
+
     return result;
 }