Patent ID: 9470774
Filing Date: 2016-10-18
CPC Classification: G01C,G01S,H04W

Claim Text:
1. A method of rendering a map for display on a mapping or navigation apparatus, in which the map is rendered for display by loading data representing particular parts of the map to be displayed from a main map data store for processing and for display by a rendering processor of the mapping or navigation apparatus and the rendering processor of the mapping or navigation apparatus has a local memory in which data representing particular parts of a map to be displayed can be stored, the method comprising: determining, when data representing a new part of the map is to be processed by the rendering processor for display, whether a part of the map for which data is already stored in the local memory is similar to the new part of the map to be processed, wherein the similarity determination uses a function that calculates a relative error between the already stored map part and the new map part and then determines whether the relative error is below a selected threshold value, wherein the selected threshold value increases as the distance from a viewer of the new map part that is to be displayed increases; and reusing data for the existing part of the map stored in the local memory for the rendering processor for displaying the new part of the map, upon the determination that a part of the map for which data is already stored in the local memory for the rendering processor is sufficiently similar to the new part of the map to be processed.