Road or other guidance is provided by displaying a structure-shape map showing building shapes and roads. Drawing of building shapes on the map is restricted according to a specific condition, e.g. the travel condition of the vehicle, or the screen scroll mode, by setting the display color for building...http://www.google.de/patents/US5908465?utm_source=gb-gplus-sharePatent US5908465 - Navigation system for displaying a structure-shape map
