A terrain mapping system is disclosed. The system has at least one sensor configured to gather a plurality of current points defining a current surface of a site and a database containing a plurality of previously-gathered points defining a previous surface of the site. The system also has a controller in communication with the at least one sensor. The controller is configured to compare a height of at least one of the plurality of the current points to a height of a corresponding at least one of the plurality of previously-gathered points and to determine if an update to the database is warranted based on the comparison. The controller is further configured to update the database if it is determined that an update is warranted.