Data processing method & device

A data processing device configured to process pixels of a field of view, wherein the field of view comprises a portion of a digital map that is to be displayed and includes a plurality of pixels, the digital map comprises a plurality of data patches which each include at least one data point, and the field of view includes a plurality of said data patches, the device comprising:

• storage for said digital map;
• a processor for accessing the digital map stored in said storage;
• and
• a data processing module controllable by said processor to:
• (i) identify for a said pixel, a data patch in which said pixel lies;
• (ii) locate a border of said data patch that lies within said field of view;
• (iii) process all pixels of said field of view that lie within said border to provide a processed data patch;
• (iv) locate, for each of any unprocessed data patches within the field of view that are adjacent a border of a processed data patch, a border of the unprocessed data patch that lies within said field of view;
• (v) process, for each unprocessed data patch, all unprocessed pixels that lie within the border of said unprocessed data patch to thereby provide a processed data patch;
• and
• (vi) repeat steps (iv) and (v) until all data patches (3) within said field of view have been processed.

Computer software comprising one or more software modules operable, when executed in an execution environment, to cause a processor to:

• (i) identify, for a pixel of a field of view that comprises a portion of a digital map that is to be displayed, a data patch in which said pixel lies, wherein the digital map comprises a plurality of data patches which each include at least one data point and said field of view comprises a plurality of said pixels;
• (ii) locate a border of said data patch that lies within said field of view;
• (iii) process all pixels of said field of view that lie within said border to provide a processed data patch;
• (iv) locate, for each of any unprocessed data patches within the field of view that are adjacent a border of a processed data patch, a border of the unprocessed data patch that lies within said field of view;
• (v) process, for each unprocessed data patch, all unprocessed pixels that lie within the border of said unprocessed data patch to thereby provide a processed data patch;
• and
• (vi) repeat steps (iv) and (v) until all data patches within said field of view have been processed.

A computer readable data storage medium having computer software stored thereon, said computer software comprising one or more software modules operable, when executed in an execution environment, to cause a processor to:

• (i) identify, for a pixel of a field of view that comprises a portion of a digital map that is to be displayed, a data patch in which said pixel lies, wherein the digital map comprises a plurality of data patches which each include at least one data point and said field of view comprises a plurality of said pixels;
• (ii) locate a border of said data patch that lies within said field of view;
• (iii) process all pixels of said field of view that lie within said border to provide a processed data patch;
• (iv) locate, for each of any unprocessed data patches within the field of view that are adjacent a border of a processed data patch, a border of the unprocessed data patch that lies within said field of view;
• (v) process, for each unprocessed data patch, all unprocessed pixels that lie within the border of said unprocessed data patch to thereby provide a processed data patch;
• and
• (viii) repeat steps (iv) and (v) until all data patches within said field of view have been processed.

A portable navigation device (PND) comprising:

• an antenna;
• a receiver operatively coupled to said antenna for receiving GPS data signals from a plurality of satellites;
• a store for a digital map that comprises a plurality of data patches which each include at least one data point;
• an interface that is user operable for the input of a start location and a destination location;
• a processor operatively coupled to said interface, said receiver and said store, said processor being configured to:
• receive said GPS data signals from said receiver and to process said GPS data signals to determine a current position of said PND in a local environment,
• to generate from map data retrieved from said store a navigation map of a local environment in which said PND current position is located, and
• to calculate, from map data retrieved from said store, a route between said start location and said destination location;
• a data processing module controllable by said processor to:
• process, data patch by data patch, a field of view that comprises a displayable portion of said digital map, wherein said field of view encompasses a plurality of said data patches when projected onto said digital map and each said data patch includes at least one data point;
• determine the boundary of each data patch within the field of view,
• process for each patch, all pixels within the field of view that fall within the boundary of that patch, and
• compute for each said pixel of a said data patch, a shading coefficient that is related to the proximity of each said pixel to said at least one data point of the data patch;
• and
• render an image for each data patch that conveys topographical information for that patch;
• a display operatively coupled to said processor and controllable by said processor to display:
• said navigation map,
• a visual representation of said route, and
• the rendered image for each said data patch within said field of view.