GENERATING AND SERVING TILES IN A DIGITAL MAPPING SYSTEM

• US 20100020091A1
• Filed: 10/05/2009
• Published: 01/28/2010
• Est. Priority Date: 03/23/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: MA, Stephen, Rasmussen, Lars Eilstrup, Rasmussen, Jens Eilstrup
• Granted Patent: US 7,962,281 B2
• Time in Patent Office: Days
• US Class Current: 345/582
• CPC Class Codes: G01C 21/36 Input/output arrangements for on-board computers
• CPC Class Codes: G01C 21/3673 Labelling using text of road map data items, e.g. road names, POI names
• CPC Class Codes: G01C 21/3881 Tile-based structures
• CPC Class Codes: G06F 16/9537 Spatial or temporal dependent retrieval, e.g. spatiotemporal queries
• CPC Class Codes: G06T 17/05 Geographic models
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: G09B 29/10 Map spot or coordinate position indicators; Map reading aids optical projection apparatus per se G03B
• CPC Class Codes: G09B 29/106 using electronic means

Abstract

Digital tile-based mapping techniques are disclosed that enable efficient online serving of aesthetically pleasing maps. In one particular embodiment, an image tile-based digital mapping system is configured for generating map tiles during an offline session, and serving selected sets of those tiles to a client when requested. Also provided are solutions for handling map labels and other such features in a tile-based mapping system, such as when a map label crosses map tile boundaries. Various processing environments (e.g., servers or other computing devices) can be employed in the system.

Claims

1. A system for generating map tiles for a digital mapping system comprising:

a tile maker for generating map tiles from digital map images using a map painter module, wherein the tile maker passes a scale of a map to the map painter module;

a map painter module for generating the digital map images at the selected scale; and

a tile storage for storing map tiles generated by the tile maker.

2. The system of claim 1, wherein the tile maker also passes a selection of geographical data sets to include in the map to the map painter module, and the map painter module generates the digital map images from the selected geographical data sets.

3. The system of claim 1, wherein the tile maker also passes a selection of features to draw to the map painter module, and the map painter module generates the digital map images including the selected features.

4. A system for generating map tiles for a digital mapping system comprising:

a map painter module for generating digital map images, wherein the map painter module includes a mapping engine library;

a tile maker for generating map tiles from the digital map images; and

a tile storage for storing map tiles generated by the tile maker.

5. The system of claim 4, wherein a configuration file controls the execution of the tile maker, and wherein data sets used to generate map tiles are defined by the configuration file.

6. The system of claim 5, wherein the configuration file specifies colors for the map.

7. A method of generating map tiles for a digital mapping system comprising:

identifying areas to be drawn and respective various zoom levels at which to draw each area;

dividing areas to be drawn into sub-areas at the respective various zoom levels;

storing a list of drawing tasks, each drawing task comprising drawing a sub-area at the respective various zoom level;

executing the list of drawing tasks by a plurality of tile makers to draw the sub-areas at the respective various zoom levels.

8. The method of claim 7, wherein the list of drawing tasks are executed by the plurality of tile makers using parallel processing.

9. The method of claim 7, wherein the sub-areas each have a pre-determined fixed size.

10. The method of claim 7, wherein the sub-areas each have a pre-determined fixed size for each zoom level.

11. A map tile serving system comprising:

a plurality of front end tile servers for serving one or more map tiles requested by a user;

a request distributor for distributing requests for map tiles between the plurality of front end tile servers; and

a plurality of back end tile servers communicatively coupled with the plurality of front end tile servers, each back end tile server having access to map tiles and configured to provide requested map tiles to a corresponding front end tile server, wherein a back end tile server caches a plurality of tiles around the requested map tile in a memory cache.

12. The system of claim 11, wherein the back end tile server caches the rest of the 64 tiles in an 8×

8 block containing the requested tile.

13. The system of claim 11, wherein the back end tile server caches a plurality of tiles around the requested map tile at the same zoom level of the requested tile.

14. The system of claim 11, wherein subsequent requests for tiles around the requested map tile are distributed to the front end tile server corresponding to the back end tile server having the cached plurality of tiles around the requested map tile.

15. The system of claim 14, wherein the tile back end server serves the tiles around the requested map tile from the memory cache.

16. A method of serving map tiles comprising:

storing the map tiles in a storage accessible by a plurality of back end tile servers;

serving the map tiles in response to a user map request, wherein the serving comprises;

distributing a map tile request to one of a plurality of front end tile servers;

providing the requested tile from one of a plurality of back end tile servers to a corresponding front end tile server;

caching a plurality of tiles around the requested map tile in a memory cache of the one of the plurality of back end tile servers.

17. The method of claim 16, wherein caching a plurality of tiles around the requested map tile comprises caching the rest of the 64 tiles in an 8×

8 block containing the requested tile.

18. The method of claim 16, wherein caching a plurality of tiles around the requested map tile comprises caching a plurality of tiles around the requested map tile at the same zoom level of the requested tile.

19. The method of claim 16, further comprising serving tiles in response to subsequent requests for tiles around the requested map tile by distributing the subsequent map tile requests to the one of the plurality of front end tile servers corresponding to the one of the plurality of back end tile servers having the cached plurality of tiles around the requested map tile.

20. The method of claim 19, further comprising serving the tiles around the requested map tile from the memory cache of the one of the plurality of back end tile servers.