DIGITAL MAP SHAPE VECTOR ENCODING METHOD AND POSITION INFORMATION TRANSFER METHOD

• US 20080031534A1
• Filed: 10/11/2007
• Published: 02/07/2008
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Adachi, Shinya
• Granted Patent: US 7,539,348 B2
• Time in Patent Office: Days
• US Class Current: 382/243
• 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 data coding method of coding data representing a shape representing geometric information, the method comprising steps of:

representing the shape using a node string, wherein each node of the node string is represented by position information having at least first and second elements;

converting the second element of the position information about each node of the node string to provide converted data of the second element so that the converted data of the second element pools about a predetermined value more than the second element of the position information; and

coding the converted data of the second element.

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

wherein the first element of the position information about the target node is expressed in information about a distance from an adjacent node and the second element of the position information is expressed in information about azimuth of a straight extended from the adjacent node, and

the converted data of the second element is expressed in a deflection angle that represents a direction difference between a link from the target node to a next node and a link from the adjacent node to the target node.

3. The shape data coding method according to claim 1, wherein the node is represented such that the first element of the position information about the node takes the constant value in a predetermined section of the shape.

4. The shape data coding method according to claim 3, wherein the node is represented in such a position that a distance from an adjacent node is constant, and the position information about the node is represented by only angle information.

5. The shape data coding method according to claim 3, wherein the node is represented in such a position that a deflection angle of a straight line extended from the adjacent node takes a constant angle, and the position information of the node is represented by only distance information

6. The shape data coding method according to claim 3, wherein the shape data is divided into a plurality of sections and the constant value is set for each section.

7. The shape data coding method according to claim 6, wherein a constant sampling section length is set for the section and the node is sampled at an interval of the sampling section length.

8. The shape data coding method according to claim 1, wherein the data are variable-length coded.

9. The shape data coding method according to claim 1, wherein the data are run-length coded.

10. The shape coding method according to claim 7, wherein the sampling section length is set depending on a curvature of the shape data.

11. A shape data coding method of coding data representing geometric information, the method comprising the steps of:

representing the shape using a node string, wherein each node of the node string is represented by position information having at least a first element and a second element;

for each one a plurality of nodes;

predicting the second element of the position of the one of the nodes on the shape, and obtaining a difference between the actual second element of the position information and the predicted second element of the position information of the one of the nodes,

wherein the resulting differences pool about a predetermined value more than the second elements of the plurality of nodes; and

coding the resulting differences into coded data.

12. The method of claim 11, wherein the predicting utilizes the second element of the position information of another node.

13. The method of claim 11, wherein the second element of the position information is an angle.

14. The method of claim 13, wherein the first element of the position information is a length between the nodes that is held constant.

15. The method of claim 11, wherein the second element of the position information is a length.

16. The method of claim 15, wherein the first element of the position information is an angle of the nodes that is held constant.

17. A method of coding shape data represented by a coordinates string, the method comprising the steps of:

sampling the shape data at a constant distance (L);

representing the sampled shape data by data of the constant distance (L) and data of an angle (θ

);

converting a data string of the angle (θ

) into a data string of an deflection angle (Φ

) representing a direction difference between the angles (θ

) of adjacent sampling points;

converting the data string of the deflection angle (Φ

) into a data string of a predicted difference value (Δ

Φ

) which is a difference between a predicted value (Sj) and the actual angle; and

variable-length-coding data string of the predicted difference value.

18. A transmitter for transmitting, to a receiving side, the coded data coded according to the method of claim 17.

19. A receiver for receiving, from a transmitter, the coded data coded according to the method of claim 17.