ENCODING DATA GENERATION METHOD AND DEVICE

• US 20070273570A1
• Filed: 08/07/2007
• Published: 11/29/2007
• Est. Priority Date: 10/17/2003
• 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 7,528,746 B2
• Time in Patent Office: Days
• US Class Current: 341/173
• CPC Class Codes: G06T 9/20 Contour coding, e.g. using detection of edges
• CPC Class Codes: G09B 29/00 Maps; Plans; Charts; Diagrams, e.g. route diagram star maps G09B27/04; devices for holding or supporting maps A47B97/02; for computing purposes G06G1/14, G09B1/16; display boards G09F
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code

Abstract

In a coded data generation method of resampling a road shape for setting a plurality of nodes, arranging position information of each node represented by a deflection angle from the immediately preceding node to generate a data string of the deflection angles, converting the deflection angles into predicted difference values each indicating the difference from the predicted value, and variable-length coding the data string of the predicted difference values, the data string of the predicted difference values when the deflection angles are converted into the predicted difference values is evaluated and a prediction expression to calculate the predicted value is selected adaptively from among a plurality of prediction expressions φ=1, φ=2, φ=3, and φ=4 based on the evaluation result. The prediction expression to calculate the predicted value is selected adaptively in response to road shape A, B, C, D, so that the data compression effectiveness is enhanced.

Claims

1. A method of coding a linear object represented by a string of latitude longitude coordinates, the method comprising:

sampling the linear object at a constant length;

representing the sampled linear object by two elements of the constant length and an angle of a line from a targeted point to a next point;

converting a data string of the angle into a data string of a deflection angle showing a direction difference between the line from the targeted point to a next point and the line from an upstream point to the targeted point;

converting the data string of the deflection angle into a data string of a predicted difference value by predicting a deflection angle on the targeted point by a prediction formula using the deflection angle on the upstream point and obtaining the difference between the predicted deflection angle on the targeted point and the actual deflection angle of the targeted point; and

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

2. The method according to claim 1, wherein the linear object is a road shape.

5. A method of decoding coded data string of a predicted difference value coded by a method according to claim 1, the method comprising:

variable-length decoding the data string of the predicted difference value;

converting the data string of the predicted difference value into a data string of deflection angle using a prediction formula used when converting the data string of the deflection angle into the data string of the predicted difference value; and

reproducing a linear projected based on the data string of the deflection angle.

6. The method according to claim 5, wherein the linear object is a road shape.

7. A receiving apparatus for decoding coded string of a predicted difference value coded by a transmission apparatus according to claim 5, the receiving apparatus comprising:

a decoding unit for variable-length decoding the data string of the predicted difference value;

a converting unit for converting the data string of the predicted difference value into a data string of deflection angle using a prediction formula used in the transmission apparatus when converting the data string of the deflection angle into the data string of the predicted difference value; and

a reproducing unit for reproducing a linear projected based on the data string of the deflecting angle.

8. The receiving apparatus according to claim 1, wherein the linear object is a road shape.

3. A transmission apparatus for coding a linear object represented by a string of latitude longitude coordinates, the transmission apparatus comprising:

a sampling unit for sampling the linear object at a constant length;

a representing unit for representing the sampled linear object by two elements of the constant length and an angle of a line from a targeted point to a next point;

a converting unit for converting a data string of the angle into a data string of a deflection angle showing a direction difference between the line from the targeted point to a next point and the line from an upstream point to the targeted point;

a converting unit for converting the data string of the deflection angle into a data string of a predicted difference value by predicting a deflection angle on the targeted point by a prediction formula using the deflection angle on the upstream point and obtaining the difference between the predicted deflection angle on the targeted point and the actual deflection angle of the targeted point; and

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

4. The transmission apparatus according to claim 3, wherein the linear object is a road shape.