| 摘要 |
An encoding data generation method includes: a step of re-sampling the road shape, a step of setting a plurality of nodes, a step of arranging position information on each node expressed by a deflection angle from a preceding-by - one node so as to generate a deflection angle data string, a step of converting the deflection angle into a predicted difference value indicating the difference from a predicted value, and a step of variable-length-encodin g the data string of the predicted difference value. The data string of the predicted difference value when the deflection angle is converted into the predicted difference value is evaluated and according to the evaluation result, a prediction equation for calculating the predicted value is adaptively selected from a plurality of prediction equations: .phi. = 1, .ph i. = 2, .phi. = 3, .phi. = 4. By adaptively selecting the prediction equation f or calculating the predicted value according to the road shape A, B, C, D, it i s possible to increase the effect of data compression.
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