Method and system for forming, updating, and using a geographic database

DETAILED DESCRIPTION To address these and other objectives, the present invention includes a method for merging of multiple databases that may be stored on different media.
According to an embodiment, a baseline template geographic database is formed.
The baseline template geographic database is organized into spatial parcels.
This organization is referred to as the baseline parcelization pattern.
Each spatial parcel is assigned a unique ID based on its position in a binary tree index that corresponds to the location of the geographic area that contains the features represented by the data contained in the parcel.
Multiple partial databases, each comprised entirely of whole parcels, can be extracted from the baseline template geographic database and used independently.
Because the parcels in these partial databases are consistent, i.
e.
, they correspond to the same baseline parcelization pattern, one or more partial databases can be merged into a single database.
These partial databases can be stored on separate media.
At run time, a single parcel index is constructed in memory or on writable media in an end user's navigation system.
The single parcel index contains references to parcels from all of the partial databases.
A parcel representing the same geographic area may be present in more than one of these partial databases.
In that case, only one of the duplicate parcels is entered into the parcel index.
If the parcels that represent the same geographic area are not the same version, a data access layer, which is a program in the end user's navigation system, selects the most up-to-date version of the parcel.
This method is used to incrementally update a geographic database.
References to parcels use media tables of contents stored on each media object.
The multiple media tables of contents are merged to create a combined media directory covering all media objects.