A DIGITAL MAPPING SYSTEM

摘要

A method for generating a sub-pixel bitmap in a tile-based digital mapping system, comprising: assigning a unique color for each source in a map to be created at a desired resolution; drawing a bitmap of the map at a higher resolution than the desired resolution, wherein each sub-pixel bitmap pixel corresponds to an NxM pixel area in the higher resolution drawing; for each of the NxM pixel areas in the higher resolution drawing, counting the number of pixels associated with each source; for each sub-pixel bitmap pixel, storing related source information and any corresponding weights, wherein a weight is used to indicate impact of a source on a sub-bitmap pixel; and representing the sub-pixel bitmap pixels using run-length encoding that indicates alternating sequences of single source pixels and mixed source pixels included in the higher resolution drawing.