Encoding data generation method and device
First Claim
1. A generation method of coded data provided by coding a linear object, said coded data generation method comprising the steps of:
- (1) resampling the linear object for setting a plurality of nodes;
(2) arranging position data of each node represented by a deflection angle from the immediately preceding node to generate a data string of the deflection angles;
(3) providing a plurality of prediction expressions to calculate a predicted value of the position data of each of the nodes based on the data string of the deflection angles;
(4) calculating the predicted value using a predetermined prediction expression of the plurality of prediction expressions;
(5) converting the data string of the deflection angles into a data string of predicted difference values each indicating the difference from the calculated predicted value; and
(6) variable-length coding the data string of the predicted difference values to provide the coded data.
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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.
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Citations
26 Claims
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1. A generation method of coded data provided by coding a linear object, said coded data generation method comprising the steps of:
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(1) resampling the linear object for setting a plurality of nodes;
(2) arranging position data of each node represented by a deflection angle from the immediately preceding node to generate a data string of the deflection angles;
(3) providing a plurality of prediction expressions to calculate a predicted value of the position data of each of the nodes based on the data string of the deflection angles;
(4) calculating the predicted value using a predetermined prediction expression of the plurality of prediction expressions;
(5) converting the data string of the deflection angles into a data string of predicted difference values each indicating the difference from the calculated predicted value; and
(6) variable-length coding the data string of the predicted difference values to provide the coded data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A coded data generation apparatus comprising:
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a shape data resample processing section for resampling a linear object for setting a plurality of nodes and arranging position data of each node represented by a deflection angle from the immediately preceding node to generate a data string of the deflection angles;
a prediction expression determination section, when the data string of the deflection angles is converted into predicted difference values indicating the difference from a predicted value to predict the position data of each of the nodes, for evaluating the data string of the predicted difference values and selecting a prediction expression to calculate the predicted value from among a plurality of prediction expressions based on the evaluation result; and
a variable-length coding processing section for converting each deflection angle contained in the data string of the deflection angles generated by said shape data resample processing section into a predicted difference value from the predicted value calculated using the prediction expression determined by said prediction expression determination section and variable-length coding a data string of the predicted difference values.
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24. A coded data reconstruction apparatus comprising:
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a coded data decoding section for decoding variable-length coded data representing position information of a linear object and reproducing shape data containing a data string of difference values each indicating the difference between a deflection angle and a predicted value;
a prediction expression determination section for determining the prediction expression used to calculate the predicted value from the provided shape data; and
a shape data reconstruction section for calculating a predicted value using the prediction expression determined by said prediction expression determination section and reproducing position information of nodes of the linear object from the data string of the predicted difference values provided by said coded data decoding section.
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25. A program for causing a computer to execute generation of code data provided by coding a linear object, said program for causing the computer to execute the steps of:
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resampling a linear object for setting a plurality of nodes and arranging position data of each node represented by a deflection angle from the immediately preceding node to generate a data string of the deflection angles;
when the data string of the deflection angles is converted into predicted difference values indicating the difference from a predicted value to predict the position data of each of the nodes, evaluating the data string of the predicted difference values;
selecting a prediction expression to calculate the predicted value from among a plurality of prediction expressions based on the evaluation result; and
converting each deflection angle contained in the data string of the deflection angles into a predicted difference value from the predicted value calculated using the determined prediction expression and variable-length coding a data string of the predicted difference values.
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26. A program for causing a computer to decode code data representing a linear object, said program for causing the computer to execute the steps of:
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decoding variable-length coded data representing position information of a linear object and reproducing shape data containing a data string of difference values each indicating the difference between a deflection angle and a predicted value;
determining the prediction expression used to calculate the predicted value from the provided shape data; and
calculating a predicted value using the determined prediction expression and reproducing position information of nodes of the linear object from the provided data string of the predicted difference values.
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Specification