Abstract: High-precision local search is performed on the Internet. A map image-rendering software provider embeds spatial keys into maps, which are then provided to producers of Internet content such as map providers. For example, a homeowner may post a message on a web bulletin board advertising his house for sale, and including a map showing the location of the house. When a search engine's web crawler encounters a page having a spatial key embedded in an image, the spatial key is indexed with the other content on the page. Because the spatial key identifies a small geographic area, indexing the content with the spatial key allows search queries to be limited by area and still provide useful results. Thus, a user of a search engine searching for “house for sale” in a specific area will be directed to web pages that meet the geographic and content search terms.

Abstract: Generalization of features in a digital map is enabled by performing a simplification of polylines. A set of chords between points on a polyline is selected such that each chord does not violate specified rules such as maximum distance from the original polyline. If a chord is acceptable, a node representing the chord is created, described by the start and end points of the chord. For pairs of nodes created, a transition from the first node to the second node is evaluated to determine whether it is acceptable. In one embodiment, a transition is acceptable if the absolute value of the angle formed by the chords is within a threshold angle from the angle formed by the original polyline at that point. If the transition is acceptable, a link between the two nodes is established. A least-cost path through the graph is chosen, and a simplified polyline is then generated.

Abstract: Automatic map generation is enabled by assigning priorities to each city in a list of cities under consideration for display on a map. A mapping engine determines a reference count for each city, indicating how frequently the city appears in one or more corpora of documents. Based on the reference count, and optionally upon other data such as population and political importance, a priority score is assigned to each city. Each city is then assigned to one of a plurality of categories according to the city's priority score. A map is then generated including cities from a specified highest number of categories. In one embodiment, cities from a higher-scored category are presented in a more significant way, e.g., in capital letters, bold type, etc., than are those in the next-highest scored category.

Abstract: Specified streets or intersections that are within a specified distance of a specified city can be found by a search, even when they are not actually in that city. For computational efficiency, some addresses are included in search results even when they exceed the specified distance from the specified city by a small amount (“false positives”). The search method guarantees that no instance of the street name within the specified distance of the specified city is erroneously missed (“false negatives”).