Efficient composition and rendering of graphical elements

摘要

A map server generates a set of base map tiles having vector descriptors, each indicating a geometry of a respective map element, in accordance with a non-raster format for rendering a first map image. The map server provides the base map tiles to the client device. Upon receiving an indication that a specific map image for the selected geographic region is to be rendered at the client device, the map server generates a set of difference map tiles that indicate changes to be made to the set of base map tiles and sends the difference map tiles to the client device for use, along with the set of base map tiles, in rendering the requested specific map image. The client device renders the new map view defined by the difference map tiles without needing to again pre-process all of the features or elements defined in the base map tiles.

主权项

1. A method for implementation in a computing device for generating map images, the method comprising:
receiving, via a communications network, a plurality of base map tiles associated with a first map image for a selected geographic region, each base map tile including one or more vector descriptors that indicates a geometry of a respective map element in accordance with a vector graphics format; preprocessing, using a processor, the vector descriptors in each base map tile to create a first set of rendering instructions for rendering the first map image as defined by the plurality of base map tiles; receiving, via the communication network, a set of difference map tiles for rendering a second map image for the selected geographic region, each of the set of difference map tiles including one or more indications of a modification of a vector descriptor to be applied to one of the plurality of base map tiles; preprocessing, using a processor, the one or more indications of the modifications of the vector descriptors to create a second set of rendering instructions for rendering the second map image; rendering, using a processor, the second map image by implementing the first set of rendering instructions and the second set of rendering instructions; and displaying the rendered second map image via a user interface.