Abstract: A program and method for route calculation for use with a navigation system and used with a map database that represents a road network in a geographic region. A route calculation program is adapted to find at least one solution route between a first location on a road network and a second location on the road network. The route calculation program includes a first search tree associated with the first location and a second search tree associated with the second location. Each search tree is adapted to hold gates. Each of the gates represents a physical position on the road network and a direction from the position to another location along a path on the road network. The route calculation program also includes at least one priority queue associated with one of the search trees. The priority queue assigns a priority to one of the gates in the associated search tree based upon an evaluation using a search algorithm.

Abstract: A method for forming a geographic database that can be used in a navigation system in which geographic data are transmitted in portions, as needed, from the geographic database to remotely located end users' computing platforms and used by the remotely located end users' computing platforms to provide navigation-related services and features to the end users as the end users travel along roads in a geographic region. The method includes the step of forming a plurality of separate collections of data from a primary copy of the geographic database. Each separate collection includes data that represent all roads of a corresponding respective separate rank, wherein a rank of a road represents a functional classification of the road such that roads that permit generally faster travel have a higher rank than roads that permit generally slower travel.

Abstract: A method performed by a navigation system to provide guidance to a driver of a vehicle when the vehicle departs from a route to a destination for which route guidance was being provided by the navigation system. Intersections that can be reached by the vehicle while calculation of a new solution route to the destination is being performed are identified. For each identified intersection, cost factors associated with the possible paths leading from the identified intersection are modified to increase the likelihood that the new solution route include those paths with the least cost factors.

Abstract: A navigation system provides a user thereof with warnings or advisories about toll gates that require exact change. The warnings or advisories are provided when the navigation system calculates a solution route to a destination specified by the user. The warnings or advisories are also provided when the user queries the navigation system about a particular specified portion of a road. The navigation system uses a geographic database that includes data about roads in a geographic region. The geographic database includes data about toll gates located along portions of roads including data about whether a toll gate along a portion or a road requires exact change.

Abstract: A navigation system and method in which geographic data are transmitted in portions, as needed, to end users' computing platforms from a central geographic database and used by the end users' computing platforms to provide navigation-related features to end users as the end users travel along roads in a geographic region.

Abstract: A feature whereby an end user of a navigation system that uses geographic data can easily report perceived errors or inaccuracies in the geographic data or other problems such as poor quality route calculation or guidance. The end user uses a user interface of the navigation system to indicate the perceived error, inaccuracy, or other problem. The navigation system includes a report program that operates in response to the end user's indication. The report program collects information indicating the error, inaccuracy, or other problem and sends a report including the collected information to a geographic database developer. The geographic database developer can use the information in the report to update a geographic database.

Abstract: A navigation system uses a geographic database to determine a solution route to a destination and provides detailed maneuvering guidance for following the solution route. In addition, the navigation system includes a preview function that provides a summary of the solution route prior to providing the detailed maneuvering guidance for following the solution route. The preview function is included in the programming of the navigation system. The preview function uses a feature incorporated in the geographic database wherein the portion of the geographic database used by the navigation system when determining a solution route includes references to another portion of the database that includes the actual text of the names of the roads represented thereby.

Abstract: A system and method are that provide an end user of a navigation program with information about walking to a desired destination in combination with information about driving to or close to the desired destination. In addition to the calculation of a route for driving to the desired destination, the navigation program uses data in a geographic database to calculate one or more routes to reach the desired destination by walking from locations within a walking threshold around the desired destination. In calculating these one or more walking routes, the navigation program uses the data in the geographic database to assess the suitability of roads around the desired destination for pedestrian travel. In calculating these one or more walking routes, the navigation program can also include road segments in the walking routes without regard for travel restrictions that only apply to vehicular traffic.

Abstract: A maneuver generation program for a computer-based navigation system. The navigation system provides a user with a series of maneuvering instructions to go from a first location to a second location in a geographic area. The series of maneuvering instructions are derived from a list of data entities that represent a route from the first location to the second location. The list of data entities includes data that represent a plurality of locations along the route at which maneuvering instructions may be provided. The maneuver generation program determines one and preferably no more than one maneuver type selected from a predetermined plurality of maneuver types for each location of the plurality of locations along the route. The maneuver generation program performs a series of tests upon data corresponding to each location. Each of the plurality of maneuver types is characterized by a unique set of tests selected from a predetermined superset of tests.

Abstract: A program and method for route calculation for use with a navigation system and used with a map database that represents a road network in a geographic region. A route calculation program is adapted to find at least one solution route between a first location on a road network and a second location on the road network. The route calculation program includes a first search tree associated with the first location and a second search tree associated with the second location. Each search tree is adapted to hold gates. Each of the gates represents a physical position on the road network and a direction from the position to another location along a path on the road network. The route calculation program also includes at least one priority queue associated with one of the search trees. The priority queue assigns a priority to one of the gates in the associated search tree based upon an evaluation using a search algorithm.

Abstract: A program and method are disclosed that provide for determining a position of an object, such as a vehicle, relative to a road network represented by a geographic database. An intermediate position density is determined along a plurality of road segments in the road network by shifting a prior position density which had been determined along the plurality of road segments by a distance traveled by the object since the prior position density had been determined. Then, the intermediate position density is modified to take into account sensor-derived data received since the prior position density had been determined to form a new position density. The position of the object is determined to be that location along the plurality of road segments at which the new position density is greatest. Also disclosed is a way to determine whether the object, such as the vehicle, is on or off the road network. A certainty measure of the new position density is computed.

Abstract: An architecture for a geographic database that supports the identification and use of names for intersections of roads located in a geographic region, and methods for use and formation thereof. The geographic database includes data that represent components of a road network in a geographic region. The geographic database includes a first plurality of data entities each of which represents an intersection of roads in the road network and a second plurality of data entities each of which represents a name of one of the components of the road network. The geographic database includes a third plurality of data entities each of which associates one of the first plurality of data entities with one of the second plurality of data entities.

Abstract: A method and system of collecting data concerning thermal properties of roads and using the collected data to form a geographic database that can be used in a vehicle safety system to implement a safety process when the vehicle approaches a location of a potential ice hazard. Data indicative of the thermal properties of roads are collected by driving along roads in a vehicle equipped with equipment that senses thermal properties of the roads upon which the vehicle is being driven. Using the collected data, a geographic database is formed that relates positions along roads to thermal properties of the roads at the positions.

Abstract: A system and method for implementing a smooth scrolling function in a map display tool used with a navigation system and a map database. The system includes a map processing layer in the map display tool having a multi-tasking abstraction layer and a synchronization object for allowing portability between different platforms. The method includes the steps of updating a display from a first graphics buffer while executing a look-ahead process in the background and filling a second graphics buffer with map information on a predicted future position.

Abstract: A system and method for distributing information for storage media, and in particular, for distributing updated navigation data, such as geographical data and navigation application programs, contained on storage media and used in in-vehicle navigation systems. A plurality of local repositories are located in a geographical area. Each of the local repositories includes updated versions of navigation data for the navigation systems. Owners of vehicles having navigation systems may visit any of the repositories from time to time where they can obtain updated versions of the navigation data for their navigation systems. Subscriptions for obtaining updated navigation data would be available to the owners of navigation systems that would entitle them to obtain updated navigation data from the repositories. Procedures for updating the local repositories are also provided. The system and method can be used for updating other types of software.

Abstract: A system and method for acquiring differentially corrected GPS data for forming a digital database of road geometry in a geographic region. A vehicle having a GPS receiver and a DGPS demodulator located therein is driven on roadways in the geographic region. The GPS receiver receives standard GPS signals and the DGPS demodulator receives DGPS signals which are used to correct the standard GPS signals. The corrected GPS signals are stored where they can be processed to create a digital database. Alternately a GPS receiver is positioned at a stationary location along with a portable DGPS demodulator. A vehicle having a GPS receiver located therein is driven on roadways in the geographic region. The GPS receiver at the stationary location is continuously operated and the DGPS demodulator is operated once to receive a DGPS signal. The DGPS demodulator can then be moved to another geographic region.