首先用计算机图象处理系统将材料截面图形数字化，并采用链码方法和精确边界寻迹方法确定图形边界。

The boundary of the area of interest is located by using chain code method and precise boundary tracking method with a computer vision system.

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备注：IBM DB2 Spatial Extender 提供了一个原生函数来确定给定的几何图形是否落入另一个几何图形边界内。

Note: IBM DB2 Spatial Extender provides a native function to find whether a given geometry falls within the boundaries of another geometry.

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它们被用来勾勒图形以显示边界，就像你在铅笔画中使用实线一样。

They were used to outline figures to show boundaries just like you might use solid lines in a pencil drawing.

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What I have up there on the diagram are calculations I made for the efficient portfolio frontier with three assets.

上面的图形是我已经算好的,三种资产的有效投资组合边界。

耶鲁公开课 - 金融市场课程节选

I did it myself using my data, but it would always look more or less like this-- slightly different positions if people use different estimates.

这幅图是我根据自己的数据画出来的，有效边界的图形大致就是如此-,随着人们采用不同的估计值,其位置会发生微小的变化。

耶鲁公开课 - 金融市场课程节选