Keeping map labels consistent across multiple zoom levels

• US 8,896,630 B1
• Filed: 10/24/2011
• Issued: 11/25/2014
• Est. Priority Date: 10/24/2011
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Miller, Andrew T.
• Primary Examiner(s): McDowell, Jr., Maurice L
• Assistant Examiner(s): Zhai, Kyle
• Application Number:
  US13/279,465
• Time in Patent Office: 1,128 Days
• Field of Search: 345/636
• US Class Current: 345/636
• CPC Class Codes: G01C 21/367 Details, e.g. road map scale, orientation, zooming, illumination, level of detail, scrolling of road map or positioning of current position marker
• CPC Class Codes: G01C 21/3673 Labelling using text of road map data items, e.g. road names, POI names
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units
• CPC Class Codes: G06T 11/20 Drawing from basic elements, e.g. lines or circles
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: G09B 29/006 Representation of non-cartographic information on maps, e.g. population distribution, wind direction, radiation levels, air and sea routes
• CPC Class Codes: G09B 29/106 using electronic means
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2340/14 Solving problems related to the presentation of information to be displayed
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T

Abstract

A computer server prepares application-specific map data responsive to a request from a client device. The application-specific map data includes map feature data and label data which itself includes information that specifies one or more zoom levels for which the label information is appropriate to display. When generating the label data, a type table that designates label style information by feature type and by zoom level may be used at the server. The map feature data may also include a relative rank for each feature that is passed to its corresponding label. The display order allows the map client, when generating the map, to select the most appropriate labels to display when the display of all possible labels would cause clutter or otherwise violate label display rules.

Claims

1. A method of operating a server device that provides data to a computer device, the data used on the computer device to display map data, wherein the map data includes map feature data used to draw map features and label data used for displaying text labels and symbols that identify map features, the method comprising:

receiving, at the server device, label data associated with a map feature, each map feature having a feature type;

receiving, at the server device, a type table that specifies style information by feature type for label data at one or more zoom levels including, for a particular feature type corresponding to a set of labels, first label style information for a first range of zoom levels and second label style information for a second range of zoom levels, wherein style information includes at least one of;

a font type, a font size, or a font color, and wherein the first label style information is different from the second label style information;

receiving, at the server device via a network, a request from the computer device for map data;

creating label data responsive to the request, the label data including label text, the first label style information, and the first range of zoom levels for which the label data is valid according to the particular feature type in the type table; and

sending map feature data and the label data responsive to the request to the computer device for use by the computer device in displaying the map feature data and the label data, wherein when the computer device receives a new request to display the map data at a new zoom level that is outside the first range of zoom levels for which the currently displayed label data is valid, the label data causes the computer device to;

receive, from the server device, new label data having a valid range that covers the new zoom level,

display the map data at the new zoom level,

determine that the difference between the new label data and the currently displayed label data is below a predetermined threshold difference, and

retain the currently displayed label data at the new zoom level.

2. The method of claim 1, further comprising grouping one or more label data by feature type, wherein the feature type identifies related text labels.

3. The method of claim 1, each map feature includes a rank, the rank specifying a relative order in which to add text labels until a threshold of labels is displayed.

4. The method of claim 1, wherein the type table includes a minimum zoom level and a maximum zoom level for an individual feature type that respectively specify i) at which zoom level label data for that feature type is available for display and ii) a zoom level above which label data for that feature type must be refreshed.

5. The method of claim 1, wherein the feature type is a park feature type, a street feature type, a city feature type, or a country feature type.

6. The method of claim 1, wherein sending the map feature data and the label data further comprises sending separate label data specified for individual zoom levels within the first range of zoom levels when the map feature data is usable over the first range of zoom levels.

7. The method of claim 1, wherein the request identifies a specific zoom level.

8. The method of claim 1, wherein the type table covers the range of zoom levels corresponding to a range of zoom levels supported by the map data.

9. The method of claim 1, wherein receiving the request for map data includes receiving an identification of a map application and wherein the type table is application specific and covers a range of zoom levels supported by the map application.

10. A method of operating a client device, the method comprising:

receiving, via a user interface, an instruction to display map data;

sending a message requesting map data from the client device to a server via a network;

receiving, from the server via the network, map data including map vector data for map features, label data including label text and first label style information, and a first range of zoom levels for which the label data is valid according to a particular feature type in a type table, wherein the type table specifies style information by feature type for label data at one or more zoom levels including, for the particular feature type corresponding to a set of labels, the first label style information for the first range of zoom levels and second style information for a second range of zoom levels, wherein style information includes at least one of;

a font type, a font size or a font color, and wherein the first label style information is different from the second label style information;

displaying the map vector data at a given zoom level;

selecting, for the given zoom level, label data with a range of zoom levels for which the label data is valid that encompasses the given zoom level; and

displaying, from the selected label data, the label text corresponding to displayed map features using the label style information for the given zoom level;

receiving a request to display the map vector data at a new zoom level;

determining that the new zoom level is outside the first range of zoom levels for which the currently displayed label data is valid;

receiving, from the server via the network, new label data having a valid range that covers the new zoom level;

displaying the map vector data at the new zoom level;

determining that the difference between the new label data and the currently displayed label data is below a predetermined threshold difference; and

retaining the currently displayed label data at the new zoom level.

11. The method of claim 10, wherein receiving the label data comprises receiving a plurality of label data, each of the plurality of label data covering a separate range of zoom levels.

12. The method of claim 10, further comprising:

receiving a request to display the map vector data at a new zoom level;

determining that the new zoom level is within the first range of zoom levels for which the currently displayed label data is valid;

displaying the map vector data at the new zoom level; and

retaining the currently displayed label data at the new zoom level.

13. The method of claim 10, further comprising:

receiving a request to display the map vector data at a new zoom level;

determining that the new zoom level is outside the first range of zoom levels for which the currently displayed label data is valid;

displaying the map vector data at the new zoom level; and

replacing the currently displayed label data with new label data having a valid range that covers the new zoom level.

14. The method of claim 13, wherein determining that the new zoom level is outside the first range of zoom levels for which the currently displayed label data is valid comprises evaluating whether the new zoom level is between a minimum zoom level and a maximum zoom level specified in the first range of zoom levels for which the currently displayed label data is valid.

15. The method of claim 13, further comprising requesting the new label data from the server when the new zoom level is outside the first range of zoom levels for which the currently displayed label data is valid and new label data having a valid range that covers the new zoom level is not available at the client device.

16. The method of claim 10, wherein each map feature comprises a rank specifying a relative order in which to add label text until a threshold of label text is displayed.

17. The method of claim 10, wherein sending the message requesting map data includes an identifier for a mapping application associated with the message;

and

wherein receiving the label data includes receiving label data applicable only to features supported by the mapping application.

18. A method of operating a server computer to generate data used by a client device to display a map, the method comprising:

receiving, at the server computer, a request for map data from the client device;

parsing, at the server computer, the request for map data into a geographic area and an application type;

responsive to the request for map data, preparing, at the server computer, application-specific map data including map feature data and label data for a first range of zoom levels using a type table, the type table specifying one or more zoom levels at which to display label data corresponding to a feature type including, for a particular feature type corresponding to a set of labels, first label style information for the first range of zoom levels and second label style information for a second range of zoom levels, wherein style information includes at least one of;

a font type, a font size, or a font color, and wherein the first label style information is different from the second label style information; and

sending the map data including the map feature data and the label data to the client device wherein when the client device receives a new request to display the map data at a new zoom level that is outside the first range of zoom levels for which the currently displayed label data is valid, the label data causes the client device to;

receive, from the server computer, new label data having a valid range that covers the new zoom level,

display the map data at the new zoom level,

determine that the difference between the new label data and the currently displayed label data is below a predetermined threshold difference, and

retain the currently displayed label data at the new zoom level.

19. The method of claim 18, wherein preparing the map data includes adding a display rank for each feature for use by the client device in prioritizing display of label data.

20. The method of claim 19, wherein preparing the type table includes a minimum zoom level and a maximum zoom level for a feature type that respectively specify i) at which zoom level label data for that feature type is available for display and ii) a zoom level above which label data for that feature type must be refreshed.