BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present technology will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
FIG. 1 is a block diagram schematically illustrating pertinent components of a wireless communications device and of a wireless communications network;
FIG. 2 is a more detailed block diagram of a wireless communications device;
FIG. 3A is a system diagram of network components which provide mapping functionality in the wireless communications devices of FIG. 1 and FIG. 2;
FIG. 3B illustrates a message exchange between a wireless communications device and a map server for downloading map content to the wireless communications device based on the system of FIG. 3A;
FIG. 3C is a diagram showing a preferred Maplet data structure;
FIG. 4 is a schematic depiction of a wireless network having an applications gateway for optimizing the downloading of map data from map servers to wireless communications devices;
FIG. 5 is a flowchart presenting steps of a method of displaying a map on a wireless device by proscribing label locations where the curvature of the label, or its associated path segment, exceeds a predetermine threshold;
FIG. 6A is an example of an onscreen map on which labels are rendered both on a curved path and on a curved non-path map feature (e.g. a river);
FIG. 6B depicts a process of determining the change in angular orientation for each successive character of the label;
FIG. 7A shows the map of FIG. 6A after it has been zoomed out, depicting the effect of the zoom factor (or magnification factor) on the curvature of labels;
FIG. 7B depicts the change in angular orientation between successive characters for the map of FIG. 7A, thus demonstrating how the change in angular orientation increases when the map is zoomed out;
FIG. 8A depicts a label on a cul-de-sac at a relatively high level of magnification, thus providing sufficient space for the map label;
FIG. 8B shows the map of FIG. 8A after it has been zoomed out, demonstrating how the map label “cul de sac” is no longer easily readable;
FIG. 9A shows a character-by-character analysis of the map label “cul de sac” at the high level of magnification used to generate the map of FIG. 8A;
FIG. 9B shows a corresponding character-by-character analysis of the map label “cul de sac” at the low level of magnification used to generate the map of FIG. 8B, showing that the change in angular orientation is greater than the change in angular orientation shown in FIG. 9A;
FIGS. 10A and 10B respectively depict an onscreen map and a corresponding collision-avoidance array wherein particular elements of the array have been proscribed as representing points where the curvature exceeds a predetermined threshold;
FIG. 10C depicts the map of FIG. 10A after repositioning of the path label “cul de sac” in order to avoid the “collision points” in the array where the curvature has been found to exceed the predetermined threshold;
FIG. 11A is a depiction of a map of a curving path upon which a curving path label is rendered;
FIG. 11B is a depiction of analysis wherein the rate of change of slope is determined for a portion of the path along which the label is to be rendered;
FIG. 11C is a depiction of the map of FIG. 11A after the path label has been repositioned to avoid the zone(s) where the rate of change of slope exceeds a predetermined threshold;
FIG. 12A depicts a map in which a 4-lane highway becomes a 2-lane highway whereupon, using conventional labelling techniques, the path label is susceptible to being wrapped or folded back on itself;
FIG. 12B depicts how slightly offset vector path segments are used to render the thickness of the 4-lane highway, thus causing the label to be wrapped or folded on itself;
FIG. 12C depicts the map of FIG. 12A after the path label has been repositioned to avoid the zone(s) where the curvature (either of the path itself or in terms of the change in orientation of each successive label character) exceeds a predetermined threshold;
FIG. 13 is a screenshot of a map rendered without detecting and avoiding sharp turns, showing how the path label “Columbia St W” is folded back on itself as the street transitions from four lanes to two; and
FIG. 14 is a screenshot of a map rendered after first detecting and avoiding sharp turns, showing how the path label “Columbia St W” is displaced to avoid the high-curvature transition point where the street goes from four to two lanes.
Patent Application
20070229513
