| 摘要 |
Systems and methods are operable to determine that a navigation system has entered a structure. An exemplary embodiment monitors a magnetic field at an outdoor position, monitors a magnetic field at a current position, compares a characteristic of the monitored magnetic field at the current position with a corresponding characteristic of the outdoor magnetic field, and determines entry into the structure at least as a function of a change in the determined characteristic of the monitored magnetic field from the corresponding characteristic of the outdoor magnetic field. |
