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谢尔本发电机

使用Sherbend算法,通过减少不必要的细节来简化线的弯曲分析的基础上。

Sherbend是一种基于约束的算法,它保留了输入数据中直线和点的空间关系。Sherbend算法通过使用直径参数来选择要泛化的折弯。在解决冲突的同时,泛化过程可以消除、减少或组合弯板。

在一条直线上概括弯板的策略如下:

  • 计算参考圆的面积,其直径由直径参数。
  • 对于每条线,确定折弯的位置。
  • 对于每个弯板,计算其周长。接下来,构造一个周长等于该周长的圆。最后,确定弯曲的调整面积,即该圆面积的75%。
  • For each bend, generalize the bend if its area is below the area of the reference circle and spatial constraints are met.
  • Repeat the above steps until there are no more bends to generalize.

输入端口

Output Ports

Parameters

Transformer

Parameters

示例

在本例中,减少了折弯(绿色= input,red= output):

In this example, a bend is eliminated:

In this example, three bends are combined into one:

The following diagram illustrates the generalization process on a single line in a real-world dataset:

This example illustrates the generalization process on a set of contours:

附加信息

线泛化的目的是减少线的细节,以便在较小的尺度上进行表示。虽然著名的Douglas-Peucker算法能够很好地减少直线中的点的数量,但是它却不能很好地去除直线中不必要的细节。这个推广者transformer在其参数下包含一系列算法,包括Douglas Peucker算法。

In comparison, the Sherbend algorithm is well suited for the generalization of natural features (contours, lakes, rivers, wooded areas, etc.) because it preserves the general shape of the line. Moreoever, if spatial constraints are enabled, the spatial relationship between the input entities are preserved. The Douglas-Peucker algorithm with a small tolerance is often used before or after Sherbend to further reduce the number of points to further fulfill the goals of generalization.

Performance and Usage Notes

  • The Sherbend algorithm iteratively detects and generalizes bends, and then detects and resolves spatial conflicts. The generalized lines from one iteration are passed to the next iteration until the lines cannot be generalized further. Due to this iterative process, the algorithm is time-intensive, which is a tradeoff to improved accuracy and quality of generalization.
  • 约束检查是一项非常耗时的操作。仅在必要时使用约束。
  • 要独立地概括每个特性,请考虑使用推广者变压器。

编辑变压器参数

使用一组菜单选项,可以通过引用工作空间中的其他元素来指定转换器参数。更高级的功能,如高级编辑器和算术编辑器,也可以在一些变压器。要访问这些选项的菜单,请单击在适用参数旁边。有关详细信息,请参阅变压器参数菜单选项.

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