added class labels for low and negative obstacles

include/structs_definitions.h

@@ -64,6 +64,8 @@ const int TERRAIN = 72;
 const int CLASS_GROUND = 46;
 const int CLASS_OBSTACLE = 100;
 const int CLASS_OVERHANGING_OBSTACLE = 15;
+const int CLASS_LOW_OBSTACLE = 24;
+const int CLASS_NEGATIVE_OBSTACLE = 26;
 
 const int CLASS_EDGE_DISCARDED_TOO_MUCH_MAHALANOBIS_DISTANCE = 25;
 const int CLASS_EDGE_ACCEPTED = 27;