Abstract: A method of representing a road network in a geographic database that facilitates determining routes between locations along the road network. In the geographic database, the road network is represented using transition point pair data. Each transition point pair data record indicates an entry point, an arm (or road segment) leading away from the entry point, an exit point, routing attributes (such as a travel cost or time), and possibly other data. Except for certain exceptions, such as multi-segment restricted driving maneuvers, the entry point and the exit point of a transition point pair are adjacent decision point intersections. A decision point intersection is an intersection at which a driver is required to make a decision which one of two or more possible road segments to take leading away from the intersection. The transition point pair data are used when calculating a route between two locations.

Abstract: A feature provided by a navigation system or other device whereby additional information about roadside signs can be provided to a driver of a vehicle while traveling along a road. The additional information may be provided automatically or in response to a request from the driver. The additional information may include a translation of the sign text into a selected language, supplementary information about the subject matter of the sign, commercial information about the subject matter of the sign, or other kinds of information. In one embodiment, the additional information is contained in a database that includes data identifying locations of roadside signs and additional information about the roadside signs. Programming in the navigation system or other device determines the location of the vehicle, uses the database to identify one or more roadside signs close to the location of the vehicle, and provides the driver with the additional information about the one or more roadside signs via a user interface.

Abstract: A method whereby a computing platform that uses geographic data that are spatially organized into parcels of a given size can specify a parcel block size larger than the given size. Thereafter, during runtime, the geographic data are accessed by the computing platform in groups of one or more parcels not larger than the parcel block size. According to one embodiment, at or after initialization of the computing platform, groupings of parcels corresponding to parcel blocks are determined. Each parcel block has a size larger than the maximum parcel size but not larger than a maximum parcel block size. Data identifying the groupings and the parcels corresponding thereto are stored on the computing platform and the data identifying the groupings and the parcels corresponding thereto are used to access all the parcels corresponding to a parcel block whenever geographic data in any one of the parcels are needed.

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 are disclosed for collecting data that relate addresses to map-referenced locations. A fleet of delivery trucks delivers items to locations throughout a geographic region. Each item to be delivered includes a tracking code. An electronic code reader device is used to record the tracking code of an item when the item is being delivered. A position determining device, such as a GPS unit, is used to determine a geographic position associated with the delivery of each item. Data indicating the tracking code of an item and the corresponding geographic position associated with the delivery are stored. Then, using data that indicate an address associated with each tracking code, each address is associated with a geographic position. This information is used to revise a geographic database, e.g., to relate addresses to map-referenced locations.

Abstract: A system and method are disclosed for collecting traffic information. One or more aircraft, such as helicopters, fly predetermined flight paths above a geographic area. The flight paths are determined so that portions of roads for which traffic information are to be collected are within the ranges of remote velocity sensors located on board the aircraft during the flights of these aircraft along their respective flight paths. Each aircraft includes positioning equipment that allows the precise position (i.e., altitude, latitude, and longitude) and attitude (i.e., roll, pitch, and yaw) of the aircraft during its flight to be determined. During a flight along the predetermined flight path, the remote velocity sensor in each aircraft is operated to perform scans of locations on roadways in the geographic area.

Abstract: A bounding route is calculated between two physical locations to determine a boundary value for which subsequent route calculations or portions thereof may be compared to. The bounding route may be calculated by selecting segments of roads that satisfy certain criteria. These criteria may be based on weighting factors or parameters such as the “least distance traveled” or the “least travel time.” The bounding route and the value may then provide any route calculation program with criteria used to determine whether a search at a particular location should continue. That is, if a search at a particular location has exceeded the criteria, or equivalently, the search has gone beyond the boundary, the search is stopped because it will most likely result in an un-optimal route. This process may then be an iterative one until an optimal search with a value less than the boundary value is found.

Abstract: A method of organizing map data on a physical storage medium is disclosed. The map data represents geographic features located in a geographic region. The method identifies at least one dense area in the geographic region. The map data representing the geographic features within the dense area have a data size exceeding a predetermined maximum size for a predetermined sized geographic area of the region. The method subdivides the map data representing the geographic features within the dense area into parcels so that the portion of map data contained in the parcel is close to a predetermined parcel size. The method subdivides the map data less the map data representing the dense area into parcels so that the portion of map data contained in the parcel is close to the predetermined parcel size. Additionally, the method locates the map data in each parcel together on the physical storage medium.

Abstract: A method and system that provides end users with the ability to exchange routing data. A route recorder application on a first computing system provides a first end user with the ability to define a route formed of specific road segments and store data that represent the route in a data file. The data file is distributed to a second end user who uses the data that represent the route in a second computing system to provide guidance for following the route.

Abstract: A navigation system with decryption functions. The navigation system may receive from a portable data storage medium an encrypted authentication key, an encrypted first portion of a geographic database, and an unencrypted second portion of the geographic database. The navigation system may then decrypt the encrypted authentication key so as to gain access to a set of verification information and to a decryption key for decryption of the encrypted first portion. The navigation system may then use the verification information to validate use of the database, such as by ensuring that the data storage medium is authorized to hold the database or that the navigation system is authorized to access the database. In turn, the navigation system may then use the decryption key to decrypt the encrypted first portion, so as to gain access to the database as a whole. The navigation system may then use information in the database to convert location coordinates into map information for presentation to a user.

Abstract: A data compression method and system that include the substitution of a substring of data characters located at a first position in a stream of data characters with a substitution code. The substitution code includes a reference to a previous position in the stream of data characters at which is located a substring of data characters that matches the substring of data characters which are being substituted located at the first position. The substitution code also includes an indication of the size of the substituted substring. The reference in the substitution code is a backwards offset to the previous position relative to the first position. According to a further aspect, Huffman encoding can be applied to the backward offsets, the substring lengths, the consecutive literal character lengths, and the literal characters themselves to reduce the data requirement size.

Abstract: A method for representing a route along a road network in a geographic region is disclosed. A database includes data representations of intersections of roads in the geographic region. Associated with the data representation for each intersection of roads are data indicating one or more nominal paths through the intersection. The nominal paths through an intersection identify, for each road segment by which the represented intersection can be entered, one and only one road segment from which the represented intersection is exited. The route is represented by indicating each intersection at which the route deviates from the nominal path into the intersection.

Abstract: A method and system for organizing and storing map data that facilitates use of the map data by navigation application programs such as those in navigation systems. The map data represent geographic features located in a region. The map data are organized into parcels such that each parcel contains a portion of the map data. The map data contained in each parcel represent those geographic features contained in a corresponding separate one of a plurality of rectangular areas located in the region. Each rectangular area has a uniform dimension in a first coordinate direction but has a dimension in the other coordinate direction such that the map data that represent the geographic features contained in the rectangular area are close to, but do not exceed, a maximum data size for a parcel.

Abstract: A navigation system provides information about railroad crossing locations. A geographic database used by the navigation system includes data that indicate whether an at-grade railroad crossing is located along a road segment. Using this information, a route calculation function in the navigation system calculates a route to a destination that avoids road segments that have at-grade railroad crossings. In this way, the delays associated with waiting for a train to cross a road are avoided.

Abstract: A system and method are disclosed that provide traffic information to end users. The traffic information is contained in traffic data messages that use location reference codes to identify locations along roads. A data structure is formed that relates a set of location reference codes assigned to locations along roads by a first data supplier to another set of location reference codes assigned locations along roads by a second data supplier. The data structure is used to form traffic data messages containing location reference codes assigned by the first data supplier based on traffic data messages containing location reference codes assigned by the second data supplier.

Abstract: A method and system for use by driver assistance systems installed in a motor vehicle to continuously provide such systems with updated data about paths along roads onto which the motor vehicle can travel from a current position of the motor vehicle as the motor vehicle travels along said roads. The method includes accessing a database that contains data that represents segments of roads and intersections of a road network located in a geographic region in which the motor vehicle is traveling and determining one or more paths along roads onto which the motor vehicle can travel from a current position of the motor vehicle. Each path is extended out to a threshold. Data representing each of the paths is provided in an organized data structure for use by the driver assistance systems.

Abstract: The Hough Transform is used to identify the circular arcs and straight line segments that coincide with the horizontal curves of roads. The Hough Transform uses data indicating positions along the roads as an input in order to identify the circular arcs and straight line segments that coincide with the roads. Data indicating the circular arcs and straight line segments are stored in a geographic database and are used to represent the roads. Radius of curvature of the road is obtained as a by product of this representation. Because the Hough Transform yields a closed form representation of road segments, the heading at any point along a road can be computed by computing the tangent to the closed form representation. Thus, heading can be accurately obtained at any point along a road.

Abstract: A method for comparing geometric shapes to each other is disclosed. The method includes determination of a rotational variation metric. The shapes to be compared are scaled so that their lengths are equal and tangent vectors at corresponding locations along the geometric shapes are determined. The angle between each pair of corresponding tangent vectors for each of these locations is then plotted as a function of the length along the geometric shapes. The variation around the mean angle between the tangent vectors for the locations along the geometric shapes being compared is the rotational variation coefficient. This process defines a rotational variation metric which indicates how closely the two geometric shapes match. The rotational variation metric can be used in various geographic applications, including vehicle positioning, sign recognition, and evaluating geographic database accuracy.

Abstract: A navigation method and system are disclosed whereby users of the systems are provided with backup driving instructions. A wireless communications system allows end users' computing devices to receive dynamic route guidance from a remotely located navigation services provider. The dynamic route guidance provides each end user with maneuvering instructions at appropriate locations along a route to a desired destination. In addition to the dynamic route guidance, the navigation service provider also provides the end users with backup driving instruction data. The backup driving instruction data can be used by an end user's computing device to provide backup driving instructions for traveling to the destination. The backup driving instruction data can be used in case wireless communications is interrupted.

Abstract: A reporting program and system whereby end users of navigation systems, or other computing platforms that use geographic data to obtain navigation-related or map-related services, can make reports about the geographic data. The reporting program can be used by end users to report perceived errors or inaccuracies in the geographic data. The end users can use their own personal computers, or other computing devices, to access the reporting program over a network, such as the Internet. When an end user accesses the reporting program, the reporting program provides a graphical map image to the end user on the end user's computing platform. The reporting program allows the end user to zoom and pan the graphical map image in order to display an image of the area about which the end user wishes to make a report.