Abstract: A navigable map database, stored on a computer-readable medium and used with a navigation application program, includes data which are spatially parcelized into a plurality of parcels. Associated with each of the plurality of parcels is a first index which associates the area represented by the data in the parcel with a plurality of sub-areas formed of the area. Also associated with each of the parcels is a second index associating each of the data in the parcel with at least one of the sub-areas. Further disclosed is a method for producing a navigable map database which is parcelized into a plurality of parcels, wherein each of the plurality of parcels includes a first index which associates the area represented by the data in the parcel with a plurality of sub-areas formed of the area and a second index associating each of the data in the parcel with at least one of the sub-areas.

Abstract: An improved method and system for storage of data that represent geographic features in a region. The data are organized into parcels each of which contains data that represent those geographic features that are located within a separate one of a plurality of rectangular areas into the region is divided. The method identifies linearly extending features that extend across multiple rectangular areas so that data representing the linearly extending feature can be included in each parcel that contains data that represents a rectangular area in which the linearly extending feature extends at least in part.

Abstract: A navigable map database, stored on a computer-readable medium and used with a navigation application program, includes data which are spatially parcelized into a plurality of parcels. Associated with each of the plurality of parcels is a first index which associates the area represented by the data in the parcel with a plurality of sub-areas formed of the area. Also associated with each of the parcels is a second index associating each of the data in the parcel with at least one of the sub-areas. Further disclosed is a method for producing a navigable map database which is parcelized into a plurality of parcels, wherein each of the plurality of parcels includes a first index which associates the area represented by the data in the parcel with a plurality of sub-areas formed of the area and a second index associating each of the data in the parcel with at least one of the sub-areas.

Abstract: A text placement program is disclosed. The text placement program provides for placement of text, such as names of geographic features, on a map image. A plurality of candidate locations for text placement are identified and provided to the text placement program. The text placement program evaluates each candidate location for text placement using an expression that includes a weighted clause of a first type indicative of whether the represented geographic feature is named at least once on the map image. If a candidate location being evaluated for text placement overlaps another candidate location, the expression for the candidate location being evaluated includes a weighted clause of a second type. One additional weighted clause of the second type is included for each occurrence of the candidate location overlapping another candidate location. For each candidate location, the text placement program evaluates the expression for two conditions: placement of text and no placement.

Abstract: An improved method and system that provides for a data access interface layer in a navigation system. The navigation system is of the type that includes a navigation application software program that provides navigating features to a user of the system and a geographic database stored on a computer-readable storage medium wherein the geographical database includes information relating to the geographical region about which the navigation system provides the navigation features to the user. The data access interface layer is preferably stored in the navigation system as a library of software functions. The data access interface layer operates in conjunction with the navigation system application software. The data access interface layer isolates the navigation application software from the geographic data which are stored on the storage medium. The data access interface layer intercepts requests by the navigation application software for geographic data.

Abstract: A system and method for storing data to represent other-than-straight map features in a computer-readable geographic database for use in a navigation system. For geographic features that are other-than-straight, a curve generated by a computable function is fitted to an image of the other-than-straight map feature. The computable function may be a polynomial equation whose shape is defined by its coefficients. In one embodiment, the polynomial equation is a type of spline curve, in particular a Bezier curve whose shape is defined by control points. The coefficients of the polynomial equation are associated with data representing the other-than-straight feature. In the case in which the polynomial equation is a Bezier curve, the control points for generating the Bezier curve are associated with the data representing the other-than-straight feature. These control points are stored in the geographic database and are used in displaying the other-than-straight geographic feature.

Abstract: A method and system for supporting alternative names of geographic locations with a navigation application program that uses a geographic database stored on a computer-readable medium. The alternative names of geographic locations include names in a plurality of different languages. Included are one or more language filters. Each of the one or more language filters associates the data records in the geographic database that are used as names for geographic locations with one or more of the plurality of different languages. A routine uses the one or more language filters so that the navigation application program can use names for geographic locations that are valid in an access language selected from among the plurality of different languages.

Abstract: A program and method are disclosed that provide for determining a position of 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 vehicle 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 sensor-derived data include data indicating three metrics, namely (1) a position of the vehicle, (2) a heading of the vehicle, and (3) a curvature history. The curvature history represents a change of heading of the vehicle as a function of distance.

Abstract: An improved method and system that provides for a data access interface layer in a navigation system. The navigation system is of the type that includes a navigation application software program that provides navigating features to a user of the system and a geographic database stored on a computer-readable storage medium wherein the geographical database includes information relating to the geographical region about which the navigation system provides the navigation features to the user. The data access interface layer is preferably stored in the navigation system as a library of software functions. The data access interface layer operates in conjunction with the navigation system application software. The data access interface layer isolates the navigation application software from the geographic data which are stored on the storage medium. The data access interface layer intercepts requests by the navigation application software for geographic data.

Abstract: A method and system for supporting alternative names of geographic locations with a navigation application program that uses a geographic database stored on a computer-readable medium. The alternative names of geographic locations include names in a plurality of different languages. Included are one or more language filters. Each of the one or more language filters associates the data records in the geographic database that are used as names for geographic locations with one or more of the plurality of different languages. A routine uses the one or more language filters so that the navigation application program can use names for geographic locations that are valid in an access language selected from among the plurality of different languages.

Abstract: A method and system for managing memory resources in a system used in conjunction with a navigation application program that accesses geographic data. The geographic data are comprised of a plurality of data records. The plurality of data records are organized into parcels, each of which contains a portion of the plurality of data records, such that the data records in each portion of the plurality of data records that forms each parcel are accessed together. One or more buffers each that forms a contiguous portion of the memory of the navigation system is provided as a cache to store a plurality of parcels. One or more data structures located outside the contiguous portion of memory identify the parcels of data stored in the cache and the locations in the cache at which the parcels are stored. The one or more data structures located outside the contiguous portion of memory in which the parcels are cached are used to manage the parcel cache to use it efficiently.

Abstract: An improved method and system that provides for a data access interface layer in a navigation system. The navigation system is of the type that includes a navigation application software program that provides navigating features to a user of the system and a geographic database stored on a computer-readable storage medium wherein the geographical database includes information relating to the geographical region about which the navigation system provides the navigation features to the user. The data access interface layer is preferably stored in the navigation system as a library of software functions. The data access interface layer operates in conjunction with the navigation system application software. The data access interface layer isolates the navigation application software from the geographic data which are stored on the storage medium. The data access interface layer intercepts requests by the navigation application software for geographic data.

Abstract: A system and method for storing data in a computer-readable database to represent curved geographic features. The database can be used in a navigation system. A computable function is used to define a curved line that represents the curved geographic feature. The computable function may be a polynomial equation whose shape is defined by its coefficients. In one embodiment, the polynomial equation is a type of spline curve, in particular a Bezier curve whose shape is defined by control points. The coefficients of the polynomial equation are associated with data representing the curved geographic feature. In the case in which the polynomial equation is a Bezier curve, the control points for generating the Bezier curve are associated with the data representing the curved geographic feature. These control points are stored in the database and are used in displaying the curved geographic feature.

Abstract: An improved method and system for storage of geographic data on physical storage media. The geographic data are stored in a manner that facilitates and enhances use and access of the data by various navigation application functions in navigation systems that use the data. The geographic data includes a parcelization that separates the geographic data into parcels having less than or equal to a maximum parcel size but having at least a desired fill percentage. The parcelization method also provides for a division arrangement that facilitates addressing and identification of the parcels. According to a further aspect, the geographic data includes special nodal entities that are used to collapse complex intersections, such as roundabouts, cloverleaves, and divided highways, into simpler data representations. The special nodal entities are associated with road segment data entities and used in a route calculation program in place of regular node entities.

Abstract: A system and method for making and using a geographic database. The geographic database represents a geographic region and is used with a navigation application program. The geographic database includes a plurality of data entities each of which represents a physical feature in the geographic region. The plurality of data entities are separated into a plurality of parcels each of which contains a grouping of data entities that represent features in the geographic area encompassed within a separate one of a plurality of rectangles which together encompass all the features in the entire geographic region represented by all of the plurality of data entities. Each of the plurality of data entities has a data entity ID.