Abstract: A data construction for storing data efficiently and a method for forming and using the data construction is disclosed. The method comprises representing a set of actual data values from an original source of data with an alternative representation. One or more parameters of a formula are determined to approximate the set of actual data values in the original source of data. For each actual data value in the original source of data, the difference between the actual data value and the value predicted therefor by the formula is determined. The difference for each actual data value is stored in a data construction on the medium along with the one or more parameters. The alternative representation preserves the information content of the actual data values from the original source of data while reducing the storage requirements for storing the information on a medium.

Abstract: A method of facilitating delivery of traffic messages is disclosed. Data indicating a plurality of traffic conditions on a road network are obtained. For each of the traffic conditions, the data provides a location description. For each of the traffic conditions, the location description is converted into a location reference code assigned by a traffic message supplier. A plurality of traffic messages representing the traffic conditions is transmitted. Each of the traffic messages includes the location reference code of the traffic condition.

Abstract: A method for collecting data for a geographic database is disclosed. Altitude data are collected using a vehicle traveling in a geographic region. A barometer associated with the vehicle supplies the altitude data. Road grade data along the roads traveled by the vehicle is derived by analyzing the altitude data. The geographic database is updated to indicate the road grade.

Abstract: A system and method are disclosed that allow a navigation system that uses a geographic database to also use the data in traffic messages broadcast by a traffic broadcast system. One aspect of a present system and method includes the formation, storage, and use of location reference data records in a geographic database used by a navigation system. These location reference data records identify certain other kinds of data records that represent physical geographic features, such as data records that represent segments of roads, as being associated with certain location reference numbers. These location reference records may be included in a geographic database installed in the vehicle or may be provided to vehicles via a wireless communication link.

Abstract: A method for displaying a zooming operation on a display screen of a computing platform. The method includes retrieving data from a geographic data storage system, possibly located on another system, displaying a starting image that shows geographic features at a first scale with a first level of detail and then displaying an ending image that shows the same geographic features at a second scale with a second level of detail. Between the displaying of the starting image and the displaying of the ending image, at least one intermediate image is displayed. The intermediate image combines two component images of at least some of the same geographic features shown in the starting or ending image. The two component images in the intermediate image are at the same scale and are registered with respect to each other so that the same geographic features represented in the two component images coincide.

Abstract: A geographic database represents roads including an altitudinal component of the geometry of the roads. The altitudinal component of the geometry of roads is represented using data that indicate straight line segments and vertical curves, in particular parabolic vertical curves. The straight lines and vertical curves are determined by providing data, indicating the altitude at a plurality of locations along portions of roads, as an input to a Hough transform to determine the straight line segments and vertical curves that coincide with the portions of the roads vertically. Then, data that define the straight line segments and vertical curves are stored to represent the altitudinal component of the geometry of the portions of the roads in the geographic database. The altitudinal variation of roads is thus expressed in closed form. From this closed form representation, the slope or grade at any point along the road can be easily computed.

Abstract: A navigation system includes a navigation-related information server and one or more customer-interface servers. Each customer-interface server receives requests for navigation-related information from end users who have end user computing platforms. The end users send their requests for navigation-related information from end user computing platforms over a data network to the customer-interface servers. In order to respond to the end users, the customer-interface servers request language and format-independent navigation-related information from the navigation-related information server. The navigation-related information server receives the requests from the customer-interface servers. To response to each request for navigation-related information, the navigation-related information server uses one or more geographic databases to formulate language- and format-independent data structures. These language- and format-independent data structures are sent to the customer-interface servers.

Abstract: A method for developing traffic messages for broadcast is disclosed. Data indicating a plurality of traffic conditions on a road network are obtained. For each of the traffic conditions, the data provides a start location at which the traffic condition begins and an end location at which the traffic condition ends. For each of the traffic conditions, a road length from the start location to the end location is determined. The traffic conditions are assigned a priority based upon the road lengths. The data indicating the traffic conditions are transmitted in the assigned priority as a plurality of traffic messages.

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 method for determining how closely two geometric shapes match is disclosed. After scaling the geometric shapes to equal length, corresponding pairs of measurement locations are determined along the linearly extending geometric shapes. Tangent vectors are determined at the measurement locations and the angle made by the tangent vectors associated with each corresponding pair of measurement locations is determined. After translating one of the geometric shapes by an angle equal to the mean of all the angles at the corresponding pairs of measurement locations, the area between the geometric shapes or the maximum deviation between the geometric shapes is determined. This is an indication of how closely the geometric shapes match. This indication can be used in various applications, including vehicle positioning, sign recognition, and evaluation of geographic database accuracy.

Abstract: A method and system for securing a data product for mass distribution. An authorization server may encrypt a portion of a data product. Further, the authorization server may assemble an authorization key that includes information indicative of an entity authorized to store the data product, and the authorization server may encrypt the authorization key. To encrypt the authorization key, the authorization server may apply a symmetric encryption algorithm based on a cryptographic key that is derived as a function of an identification code associated with the authorized entity. The encrypted portion of the data product, the encrypted authentication key, and the remainder of the data product may then be stored on the authorized entity, which may be provided to a machine authorized to access the data product. The machine is preferably programmed to derive the second decryption key, use it to decrypt the authentication key, and then use the authentication key to validate use of the data product.

Abstract: An in-vehicle navigation system includes a receiver for receiving real-time traffic information (RTTI), a database for storing routine trip information, and a processor for running a regular route application. The regular route application includes a learning mode program and an operational mode program. The learning mode program records information regarding trips regularly taken by a vehicle and populates the database with records of routine trip information. The recorded trip information can include driver identifiers, trip departure times, origin points, destination points, dates of travel, days of travel, and route data. When the vehicle begins a new trip, the operational mode program determines whether the vehicle is engaging in a routine trip. This is accomplished by comparing current vehicle location or departure time information to routine trip information in the database.

Abstract: A method for providing visual continuity when performing a zooming or panning operation with a graphical map shown on display screen of a computing platform. When a user of the computing platform operates the user interface thereof to perform a zooming or panning operation, a first map view of a first geographic area is replaced with a second map view of a second geographic area, such that at least a portion of the first and second geographic areas overlap. In order to provide visual continuity, a transition view is shown on the display screen of the computing platform between the showing of the first map view and the showing of the second map view. The transition view is shown for several seconds immediately after the user operates the user interface to perform the zooming or panning operation. The transition view shows either the first map view or the second map view. The transition view also includes a boundary line that is overlaid on the map view being shown.

Abstract: A method is disclosed for obtaining altitude-related data along roads. A vehicle includes equipment capable of determining the current absolute positions of the vehicle as it is being driven. The vehicle also includes equipment capable of determining a distance traveled by the vehicle. Two points along a road are selected. Altitude-related data are determined as a function of the horizontal difference between the absolute positions of the two points and the distance traveled by the vehicle between the two points.

Abstract: A navigation system includes a driving profile program. The driving profile program collects information about an end user's driving activity. The information relates to trips made by the end user. The information includes departure times, intermediate stops, arrival times, purposes of the trips, and so on. After collecting this information over a period of time, the driving profile program analyzes the end user's driving activity. The driving profile program provides the end user with a driving activity profile. In addition, the driving profile program determines ways to reduce the amount of time and/or expense that the end user spends traveling in his/her vehicle and suggests modifications to the end user's driving activity that would save the end user time or expense.

Abstract: A method and system for collecting meteorological data. A plurality of vehicles travel on roads in a geographic region. Each of the vehicles includes sensor equipment that senses at least one meteorological condition. The sensor equipment may be used to support other vehicle systems, such as vehicle safety systems or a vehicle navigation system. Each of the vehicles includes a program run on a computing device in the vehicle that prepares messages containing data indicative of the one or more meteorological conditions sensed by the sensor equipment. The messages are sent wirelessly from the vehicle to a meteorological data collection service that collects the data and uses the data for weather modeling or forecasting.

Abstract: A method for determining a polygonal intersection of a first polygon and a second polygon. An intersection of the boundary of the first polygon with the boundary of the second polygon is located by finding a point from which at least three portions of boundaries extend. From this point, a first portion of the boundary of the polygonal intersection is determined by identifying a portion of the boundary of the first polygon that is located inside the second polygon. Each subsequent portion of the boundary of the polygonal intersection is determined by selecting that portion of the boundary of either the first polygon or the second polygon that (1) connects to a leading end of a current portion of the boundary of the polygonal intersection and (2) forms the least angle with the current portion of the boundary of the polygonal intersection.

Abstract: A reporting program and system for updating a master copy of a geographic database is disclosed. According to the method and system, reports are obtained that relate to data contained in a geographic database. Satellite images of the geographic locations represented by the data in the reports are obtained. The satellite images are analyzed to confirm a need to make changes to the master copy of the geographic database based on the reports. After confirming the need to make, the changes, the master copy of the geographic database is updated.

Abstract: The degree to which a linearly extending feature, such as a road, curves is indicated using a bowing coefficient. The bowing coefficient at a given location along a linearly extending feature is determined by comparing the distance along the feature between two points on either side of the given location (or an approximation of the distance) to a straight-line distance between these same two points. Bowing coefficient data can be used by various vehicle systems that require information about the curvature of linearly extending features, such as roads upon which the vehicle is traveling.

Abstract: A method of obtaining data for a geographic database is disclosed. Data indicating a plurality of locations along roads including data indicating altitudes at the plurality of locations is provided. Road grade values for a plurality of subsections of the road are computed; each of the subsections is a portion of the road between two of the locations. A plurality of temporary change points are identified as joining two adjacent subsections having road grade values that differ by a value greater than a predetermined amount. Road grade values for each part of the road between adjacent temporary change points are computed. Consecutive parts of the road having road grade values that falls within a predetermined range are grouped into at least one constant road grade section. The geographic database stores data that define the constant road grade section.