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: Dehydration of routes enables transmitting a description of a route requiring much less space than full specification of the route. A series of “breadcrumbs” and hints are used for dehydration. A breadcrumb includes coordinates of a point, a heading at which the route enters the breadcrumb, and a heading at which the route leaves the breadcrumb. A dehydration module places a breadcrumb at the location marking the beginning of the route, and having a leaving heading identifying the link in the original route. The node at the end of each link in the original route is examined. If the link leaving the node is the most parallel link to the link entering the node, nothing is added to the dehydrated route. If not, a breadcrumb is added to the dehydrated route, specifying the coordinates of the point, the entering heading of the breadcrumb and the leaving heading of the breadcrumb.

Abstract: A routing module identifies POIs that can be reached from a route with a cost less than distance m. A routing engine performs a reverse exploration on nodes in the planned route to locate POIs from which the route can be reached with a cost of less than a second cost n. POIs identified as being reachable from the route with a cost of less than m, and from which the route is reachable with a cost less than n are then further filtered to identify a subset of the POIs for which the sum of the time or distance from the route to the POI and the time or distance from the POI back to the route is less than a threshold time or distance, t.

Abstract: Dehydration of routes enables transmitting a description of a route requiring much less space than full specification of the route. A series of “breadcrumbs” and hints are used for dehydration. A breadcrumb includes coordinates of a point, a heading at which the route enters the breadcrumb, and a heading at which the route leaves the breadcrumb. A dehydration module places a breadcrumb at the location marking the beginning of the route, and having a leaving heading identifying the link in the original route. The node at the end of each link in the original route is examined. If the link leaving the node is the most parallel link to the link entering the node, nothing is added to the dehydrated route. If not, a breadcrumb is added to the dehydrated route, specifying the coordinates of the point, the entering heading of the breadcrumb and the leaving heading of the breadcrumb.

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: 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: Dehydration of routes enables transmitting a description of a route requiring much less space than full specification of the route. A series of “breadcrumbs” and hints are used for dehydration. A breadcrumb includes coordinates of a point, a heading at which the route enters the breadcrumb, and a heading at which the route leaves the breadcrumb. A dehydration module places a breadcrumb at the location marking the beginning of the route, and having a leaving heading identifying the link in the original route. The node at the end of each link in the original route is examined. If the link leaving the node is the most parallel link to the link entering the node, nothing is added to the dehydrated route. If not, a breadcrumb is added to the dehydrated route, specifying the coordinates of the point, the entering heading of the breadcrumb and the leaving heading of the breadcrumb.

Abstract: A system and processes for generalizing a collection of objects using points not necessarily part of the original objects are provided. Generalization of features in a digital map includes moving points to round number coordinates, while keeping topology correct and not moving points outside an allowed distance range, thus substantially reducing the size of the data so generalized. However, doing so requires moving points from the original polyline to new points. Generalization of polylines to points preferentially chosen from a relatively sparse set is described.

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: A routing module identifies POIs that can be reached from a route with a cost less than distance m. A routing engine performs a reverse exploration on nodes in the planned route to locate POIs from which the route can be reached with a cost of less than a second cost n. POIs identified as being reachable from the route with a cost of less than m, and from which the route is reachable with a cost less than n are then further filtered to identify a subset of the POIs for which the sum of the time or distance from the route to the POI and the time or distance from the POI back to the route is less than a threshold time or distance, t.

Abstract: A system includes a GPS module, user interface module, database and routing engine. To find nearby POIs in one embodiment the routing engine identifies POIs in the database located within a threshold distance from the planned route in Euclidean distance. The routing engine filters the results by exploring the road network to determine whether each of the POIs is within the threshold distance of the route in driving distance. The filtering may include exploring outward from the POI, until all roads within the threshold distance are explored or the route is reached; alternatively, distance to the POIs is checked by exploring outward from the route until all roads within the threshold distance of the route have been exposed. For those POIs reached in the exploration, the nearest point on the route and the distance to that point are known. Similar searches are performed based on driving time rather than distance.

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”).

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: 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”).

Abstract: Display of digital maps with gradually changing perspective is provided. A perspective engine selects from among possible foreshortening ratios depending on the selected map scale. In one embodiment, the perspective engine uses a fixed perspective view corresponding to each of a fixed set of scales. In alternative embodiments, there is a continuum of scales, and parameters are specified as functions of the scale, rather than as fixed values. In general, at smaller scales—that is, more zoomed-out—the displayed perspective appears to be more flat, as though looking straight down at the map. At larger scales—more zoomed-in—the map is displayed with increasing perspective. In some embodiments, once a threshold scale is reached, continuing to zoom in does not additionally increase the perspective; similarly, once a threshold zoomed-out scale is reached, the map continues to be displayed in a two-dimensional flat appearance.

Abstract: Dehydration of routes enables transmitting a description of a route requiring much less space than full specification of the route. A series of “breadcrumbs” and hints are used for dehydration. A breadcrumb includes coordinates of a point, a heading at which the route enters the breadcrumb, and a heading at which the route leaves the breadcrumb. A dehydration module places a breadcrumb at the location marking the beginning of the route, and having a leaving heading identifying the link in the original route. The node at the end of each link in the original route is examined. If the link leaving the node is the most parallel link to the link entering the node, nothing is added to the dehydrated route. If not, a breadcrumb is added to the dehydrated route, specifying the coordinates of the point, the entering heading of the breadcrumb and the leaving heading of the breadcrumb.

Abstract: A system and processes for generalizing a collection of objects using points not necessarily part of the original objects are provided. Generalization of features in a digital map includes moving points to round number coordinates, while keeping topology correct and not moving points outside an allowed distance range, thus substantially reducing the size of the data so generalized. However, doing so requires moving points from the original polyline to new points. Generalization of polylines to points preferentially chosen from a relatively sparse set is described.

Abstract: A method of clustering multi-dimensional related data performed by identifying features from a collection of data, each of said features being represented by a vertex, selecting pairs of features that it is desirable to cluster together, connecting the pair of vertices representing every selected pair of features by an edge, assigning a score to every edge according to a predetermined formula, selecting an edge having the highest score, creating a new vertex by merging the vertices connected by the selected edge, creating new edges between the new vertex and the vertices previously connected to the merged vertices, and repeating this procedure until every edge has a predetermined score.

Abstract: A navigation system comprising a relative positioning system (RPS) with dead reckoning and map matching and an absolute positioning system (APS) is provided and operated in such a manner that APS position information is used for updating RPS position and contour of equal probability (CEP) information as required. The APS may comprise a Loran-C or a global positioning system (GPS). Different criteria are used for resetting the RPS depending on whether or not the navigation system comprises a Loran-C or a GPS due to the different levels of precision of the Loran-C and the GPS. When the RPS is reset or updated, it is updated to the current APS position with its offset, if any. Its contour of equal probability (CEP) may also be adjusted.