Template-based map distribution system

A method for displaying a map on a client device, the method comprising:

• storing map data on a server, the map data comprising a plurality of layers, each layer comprising vector information delineating features in the map belonging to a respective feature category;
• defining a set of templates on the server, each such template being associated with a respective one of the layers and indicating a visual characteristic of the features in the layer with which the template is associated;
• downloading to the client device from the server at least a first subset of the templates, and saving the downloaded templates in the first subset in a memory of the client device;
• receiving a request from the client device to view a selected area of the map;
• determining a second subset of the templates on the server that is required to view the selected area of the map on the client device;
• comparing the templates in the second subset to the templates saved in the memory of the client device, and downloading to the client device from the server only elements of the second subset that are absent from the templates in the memory of the client device;
• downloading to the client device from the server the vector information in a portion of one or more of the layers of the map data corresponding to the selected area of the map;
• and
• rendering on the client device, based on the downloaded vector information, an image of the selected area of the map in accordance with the visual characteristic indicated by the downloaded templates.

Apparatus for displaying a map on a client device having a given display capability, the apparatus comprising:

• a memory;
• and
• a mapping server, which is adapted to store map data in the memory, the map data comprising a plurality of layers, each layer comprising vector information delineating features in the map belonging to a respective feature category, and which is further adapted to store a set of templates, which are defined on the server responsively to the display capability of the client device, each such template being associated with a respective one of the layers and indicating a visual characteristic of the features in the layer with which the template is associated,
• the server being further adapted to download to the client device at least a subset of the templates and the vector information in a portion of one or more of the layers of the map data corresponding to a selected area of the map, so as to cause the client device to render an image of the selected area of the map, based on the downloaded vector information, in accordance with the visual characteristic indicated by the downloaded templates.

Apparatus for displaying a map on a client device, the apparatus comprising:

• a memory;
• and
• a mapping server, which is adapted to store map data in the memory, the map data comprising a plurality of layers, each layer comprising vector information delineating features in the map belonging to a respective feature category, and to store a set of templates, each such template being associated with a respective one of the layers and indicating a visual characteristic of the features in the layer with which the template is associated,
• the server being further adapted to download to the client device at least a first subset of the templates, causing the client device to store the downloaded templates in the first subset in a memory of the client device, and upon receiving a request from the client device to view a selected area of the map, to determine a second subset of the templates on the server that is required to view the selected area of the map on the client device,
• the server being still further adapted, based on a comparison of the templates in the second subset to the templates saved in the memory of the client device, to download to the client device only elements of the second subset that are absent from the templates in the memory of the client device, and to download to the client device the vector information in a portion of one or more of the layers of the map data corresponding to the selected area of the map, so as to cause the client device, based on the downloaded vector information, to render an image of the selected area of the map in accordance with the visual characteristic indicated by the downloaded templates.

A computer software product for displaying a map on a client device, the product comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to access map data stored in a server memory, the map data comprising a plurality of layers, each layer comprising vector information delineating features in the map belonging to a respective feature category, and to access a set of templates in the server memory, each such template being associated with a respective one of the layers and indicating a visual characteristic of the features in the layer with which the template is associated,

• the instructions further causing the computer to download to the client device at least a first subset of the templates, causing the client device to store the downloaded templates in the first subset in a memory of the client device, and upon receiving a request from the client device to view a selected area of the map, to determine a second subset of the templates in the server memory that is required to view the selected area of the map on the client device,
• the instructions still further causing the computer, based on a comparison of the templates in the second subset to the templates saved in the memory of the client device, to download to the client device only elements of the second subset that are absent from the templates in the memory of the client device, and to download to the client device the vector information in a portion of one or more of the layers of the map data corresponding to the selected area of the map, so as to cause the client device, based on the downloaded vector information, to render an image of the selected area of the map in accordance with the visual characteristic indicated by the downloaded templates.