Methods and systems for downloading and viewing maps

• US 20030231190A1
• Filed: 03/17/2003
• Published: 12/18/2003
• Est. Priority Date: 03/15/2002
• Status: Abandoned Application

• Current Assignee: Summus Limited
• Original Assignee: Summus Limited
• Inventors: Chung, Do Hyun, Panda, Prasanjit, Zhou, Jiangying, Jawerth, Bjorn, Rade, Johan
• Application Number:
  US10/390,124
• Publication Number:
  US 20030231190A1
• Time in Patent Office: Days
• US Class Current: 345/660
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: G06T 9/20 Contour coding, e.g. using detection of edges
• CPC Class Codes: G09G 2340/145 related to small screens
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals

Abstract

Embodiments of the present invention comprise a method for transmitting map data, a method for displaying map data, a system for processing and displaying map data, and a method for rendering line segments on a pixel display. A preferred method for transmitting map data comprises receiving, layering, and simplifying map data and transmitting some of the simplified data. A preferred method for displaying map data comprises receiving compressed map data, decompressing the received data, and rendering the decompressed data on a display device. A preferred system for processing and displaying map data comprises a map database, a map generation sub-system, a map rendering sub-system, and a display device. A preferred method for rendering line segments on a pixel display, comprises, for a line segment from a first endpoint to a second endpoint, rounding off the slope of the line segment and calculating pixel locations based on that rounded off slope.

Claims

1. A method for transmitting map data, comprising:

receiving unprocessed vector formatted map data regarding a selected geographical region;

layering said received map data;

simplifying said layered map data; and

transmitting some or all of said simplified data to a remote device.

2. A method as in claim 1, further comprising packing at least some of said simplified data.

3. A method as in claim 1, further comprising compressing at least some of said simplified data.

4. A method as in claim 1, wherein a first portion of said simplified data is transmitted at a first time, and further comprising transmitting a second portion of said simplified data at a second time.

5. A method as in claim 1, wherein said step of layering said stored map data comprises layering said stored map data into a base layer and one or more detail layers.

6. A method as in claim 1, wherein said step of simplifying said layered map data comprises lossy simplification.

7. A method as in claim 1, wherein said step of simplifying said layered map data comprises lossless simplification.

8. A method as in claim 7, wherein said lossless simplification comprises poly-line grouping.

9. A method as in claim 7, wherein said lossless simplification comprises name processing.

10. A method as in claim 3, wherein said step of compressing comprises compression of poly-lines.

11. A method as in claim 3, wherein said step of compressing comprises compression of names.

12. A method as in claim 6, wherein said lossy simplification comprises preservation of topological and features attributes and modification of geometrical attributes.

13. A method as in claim 6, wherein said lossy simplification comprises poly-line simplification.

14. A method as in claim 13, wherein said poly-line simplification comprises a Douglas-Peucker algorithm.

15. A method as in claim 3, wherein said step of compressing said simplified data comprises text compression.

16. A method as in claim 15, wherein said text compression comprises a Lempel-Ziv text compression algorithm.

17. A method for displaying map data, comprising:

receiving compressed, layered, vector formatted map data regarding a selected geographic region;

decompressing said received data; and

rendering said decompressed data on a display device, wherein said rendering comprises multi-layer rendering.

18. A method as in claim 17, wherein said step of decompressing comprises decompression of poly-lines.

19. A method as in claim 17, further comprising:

subsequently receiving additional compressed, layered, vector formatted data regarding said selected geographical region

decompressing said subsequently received additional data; and

rendering said decompressed subsequently received additional data on said display device, wherein said rendering comprises multi-layer rendering.

20. A method as in claim 17, wherein said step of decompressing comprises decompression of names.

21. A method as in claim 17, wherein said step of rendering comprises vector-based poly-line rendering.

22. A method as in claim 17, wherein said multi-layer rendering comprises rendering text and poly-lines simultaneously.

23. A method as in claim 17, wherein said map data comprises poly-line data corresponding to poly-lines comprised of line segments and wherein said multi-layer rendering comprises classifying said line segments into four types.

24. A method as in claim 17, wherein said rendering comprises progressive text rendering based on a scoring system.

25. A method as in claim 17, wherein said rendering comprises text de-cluttering.

26. A method as in claim 25, wherein said text de-cluttering is based on a scoring system.

27. A system for processing and displaying map data, comprising:

a map database;

a map generation sub-system in communication with said map database;

a map rendering sub-system in communication with said map generation sub-system; and

a display device storing software comprising said map rendering sub-system;

wherein said map generation sub-system performs map data selection, map data layering, and map data simplification.

28. A system as in claim 27, wherein said map generation sub-system performs map data compression.

29. A system as in claim 27, wherein said map rendering sub-system performs multi-layer rendering.

30. A system as in claim 27, wherein said map data simplification comprises lossy simplification and lossless simplification.

31. A system as in claim 27, wherein said map rendering sub-system performs progressive text rendering based on a scoring system.

32. A system as in claim 27, wherein said map rendering sub-system performs text de-cluttering.

33. A method for rendering line segments on a pixel display, comprising:

performing calculations using m-bit integers, where m is an even integer and m is greater than or equal to 32; and

for a line segment from a first endpoint to a second endpoint;

rounding off the slope of the line segment to 2<sup>−

m/2</sup> precision; and

calculating pixel locations corresponding to points between and including said first and second endpoints based on said rounded off slope, wherein a unique pixel location corresponding to said second endpoint has the same location it would have had if said slope had not been rounded off.

34. A method as in claim 33, wherein said pixel display is not more than 2^m/2−

1 pixels wide.