How can I tell if a list of 3 or more line segments form a closed region (in 3d)?

我如何能告诉如果一个列表的3个或更多的线段，形成一个封闭的区域(3d) ？

youdao

The area and perimeter of the closed region are two important parameters for image analysis and recognition.

区域面积和周长是图像分析与识别过程中所需的两个重要参数。

youdao

If the line crosses an odd number of path segments, the starting point is inside the closed region and is therefore part of the fill or clipping area.

如果直线和奇数的路径线段交叉，则开始点是在关闭的区域中，因此是填色或裁剪区域的一部分。

youdao

There is no independent confirmation of the tolls, as the region is closed to outsiders and is dangerous even for local reporters to visit.

VOA: standard.2009.10.24

There is no independent confirmation of the tolls, and the region has been closed to outsiders.

VOA: standard.2009.10.28

Kibbutz Bahan in the Hefer Valley region closed down its old dairy and chicken farms to open the Utopia Orchid Park.

BBC: Kick back on a kibbutz

Bridges and tunnels were closed across the region, including the Verrazano-Narrows Bridge, the Holland Tunnel, the Tappan Zee Bridge and all spans across the East River.

WSJ: Sandy Wallops Region

But keep in mind, I first moved to Chicago to be a community organizer with churches who were trying to deal with the devastation of steel plants that had closed in that region.

CNN: Part 1 of CNN Democratic presidential debate