Digital map shape vector encoding method and position information transfer method

• US 20030093221A1
• Filed: 09/13/2002
• Published: 05/15/2003
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Adachi, Shinya
• Granted Patent: US 7,333,666 B2
• Time in Patent Office: Days
• US Class Current: 701/208
• CPC Class Codes: G06T 9/008 Vector quantisation
• CPC Class Codes: G06T 9/20 Contour coding, e.g. using detection of edges
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution

Abstract

It is an object to provide a method of coding the position information of a digital map in a small data volume by utilizing a compressing and coding technique. In a coding method of coding data indicative of a shape vector on a digital map, an arithmetic processing is carried out over position information about a node string and a shape which indicate the shape vector to be represented by data having a statistical deviation, and the data having the statistical deviation are coded to reduce a data volume. It is possible to considerably decrease a transmission data volume in the case in which the vector shape of the digital map is to be transferred.

Claims

1. A shape vector data coding method of coding data representing a shape vector on a digital map,

wherein an arithmetic processing is carried out over position information about each node of a node string representing the shape vector, the position information is converted into data having a statistical deviation, and the data are coded to reduce a data volume.

2. The shape vector data coding method according to claim 1,

wherein the position information about the node is expressed in information about a distance from an adjacent node and an angle of a straight line extended from the adjacent node, and the distance or angle is expressed in data having a statistical deviation, thereby coding the data.

3. The shape vector data coding method according to claim 1 or 2,

wherein the position information about the node is converted into difference data from a statistical predicted value and the difference data are coded.

4. The shape vector data coding method according to claim 2,

wherein the information about the angle is expressed in a deviation angle and the deviation angle is coded.

5. The shape vector data coding method according to claim 2,

wherein the information about the angle is expressed in a difference for a statistical predicted value of the deviation angle and the difference is coded.

6. The shape vector data coding method according to claim 2,

wherein the information about the distance is represented by a difference for a statistical predicted value of the distance and the difference is coded.

7. The shape vector data coding method according to claim 1 or 2,

wherein the node is resampled such that at least one element in the position information about the node takes a constant value in a predetermined section of the shape vector.

8. The shape vector data coding method according to claim 7,

wherein the node is resampled in such a position that a distance from an adjacent node is equal, and the position information about the node is represented by only angle information.

9. The shape vector data coding method according to claim 7,

wherein the node is resampled in such a position that a deviation angle of a straight line extended from an adjacent node takes a constant angle, and the position information of the node is represented by only distance information.

10. The shape vector data coding method according to claim 7,

wherein the shape vector is divided into a plurality of sections and the constant value is set for each section.

11. The shape vector data coding method according to claim 10,

wherein a constant resample section length is set for the section and the node is resampled at an interval of the resample section length.

12. The shape vector data coding method according to claim 1 or 2,

wherein an arithmetic processing is carried out over position information about a node or an interpolation point which is included in the shape vector of the digital map and the position information is converted into data having a statistical deviation.

13. The shape vector data coding method according to claim 1,

wherein an arithmetic processing is carried out over information about a node string of a spline function approximating the shape vector to be converted into data having a statistical deviation.

14. The shape vector data coding method according to claim 1 or 2,

wherein the data are variable-length coded to reduce a data volume.

15. The shape vector data coding method according to claim 1 or 2,

wherein the data are run-length coded to reduce a data volume.

16. The shape vector data coding method according to claim 11,

wherein the resample section length is set depending on a curvature of the shape vector.

17. The shape vector data coding method according to claim 1,

wherein an allowable error of the shape vector is calculated and a quantized digit number is decreased when the data are coded so as not to exceed the allowable error.

18. The shape vector data coding method according to claim 16,

wherein the shape vector is approximated by a circular arc and a straight line, and the resample section length is set for each section of the approximated circular arc or straight line.

19. A position information transmitting method for a digital map in which a transmitting side transmits shape data representing a shape vector on the digital map and a receiving side carries out map matching based on the received shape data and specifies the shape vector on a self-digital map,

wherein the transmitting side transmits shape vector data coded by the coding method according to any of claims 1 to 18 and the receiving side decodes the received data and reproduces a shape, and specifies a shape vector corresponding to the reproduced shape by the map matching.

20. The position information transmitting method according to claim 19,

wherein the transmitting side transmits data including a code table used for coding and the receiving side reproduces a shape by using the received code table.

21. The position information transmitting method according to claim 19,

wherein the transmitting side sets a resample section length within such a range that mismatching is not generated on the receiving side.

22. The position information transmitting method according to claim 19,

wherein the transmitting side decreases a quantized digit number within such a range that mismatching is not generated on the receiving side.

23. The position information transmitting method according to claim 19,

wherein the transmitting side approximates the shape vector by a circular arc and a straight line within such a range that mismatching is not generated on the receiving side.

24. The position information transmitting method according to claim 19,

wherein the transmitting side previously creates and holds a code table to he used for coding and codes the shape vector by using the code table.

25. The position information transmitting method according to claim 24,

wherein the transmitting side previously holds data on the shape vector coded by using the code table and selects data to be transmitted from the held data.

26. The position information transmitting method according to claim 19,

wherein the transmitting side transmits data representing a shape of a polygon on the digital map as the coded shape vector data.

27. A transmitter for transmitting, to a receiving side, shape data representing a shape vector on a digital map for specifying a shape by map matching, comprising:

code table calculating means for carrying out an arithmetic processing over position information of each node of a node string representing the shape vector on the digital map, converting the position information into data having a statistical deviation and generating a code table using coding for the data based on an occurrence distribution of the data; and

position information converting means for coding position information of each node of the shape vector to be transmitted to the receiving side by using the code table and for generating shape data to be transmitted to the receiving side.

28. A transmitter for transmitting, to a receiving side, shape data representing a shape vector on a digital map for specifying s shape by map matching, comprising;

position information converting means for coding position information of each node of the shape vector to be transmitted to the receiving side by using a code table generated by means of another device and for generating the shape data to be transmitted to the receiving side.

29. A receiver for receiving shape data representing a shape vector on a digital map from a transmitting side and for carrying out map matching to specify the shape vector on a self-digital map, comprising:

code data decoding means for decoding the received data which are coded and for reproducing the shape data represented by position information on the digital map; and

map matching means for carrying out map matching by using the shape data thus reproduced, thereby specifying the shape vector on the self-digital map.

30. A program of a transmitter for transmitting, to a receiving side, shape data representing a shape vector on a digital map for specifying a shape by map matching,

wherein a computer is caused to execute:

a procedure for resampling the shape vector on the digital map in a fixed length, thereby setting a node;

a procedure for carrying out an arithmetic processing over position data of the node to be converted into data having a statistical deviation; and

a procedure for generating a code table to be used for coding the data based on an occurrence distribution of the data having a statistical deviation.

31. A program of a transmitter for transmitting, to a receiving side, shape data representing a shape vector on a digital map for specifying a shape by map matching,

wherein a computer is caused to execute:

a procedure for resampling the shape vector in a fixed length, thereby setting a node;

a procedure for carrying out an arithmetic processing over position data of the node to be converted into data having a statistical deviation; and

a procedure for converting the data having a statistical deviation into a code representation by referring to a code table.

32. A program of a receiver for receiving shape data representing a shape vector on a digital map from a transmitting side and for carrying out map matching to specify the shape vector on a self-digital map,

wherein a computer is caused to execute:

a procedure for decoding the received data which are coded by referring to a code table;

a procedure for reproducing shape data represented by position information on the digital map from the decoded data; and

a procedure for carrying out map matching by using the shape data thus reproduced, thereby specifying the shape vector on the self-digital map.