| 摘要 |
The generation of contour plot images from elevation data in real time for use in a digital moving map. The contour line interval is dynamically selectable. The elevation data is scanned in 2 dimensions simultaneously, but in a single pass. As the elevation data is scanned for the given contour line interval, a history is maintained of the contour line elevation state in both dimensions. At any point, only comparisons against the two historical values are required to determine if a point on a contour line exists.
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