Python形状相交：平行平面 [英] Python Shapely intersection: parallel planes

问题描述

我正在研究确定两个三维物体（三角形面）之间的关系（边界/内部交点），并偶然发现了很好看，我有兴趣使用它来代替实现我自己的点/段/光线/三角交集函数。

然而，我正在运行进入以下问题：

 >>> from shapely.geometry import Polygon 
>>> poly = Polygon（[（0,1,1），（1，-1,1），（ -  1，-1,1）]）
>>> poly2 = Polygon（[（0,1,0），（1，-1,0），（ -  1，-1,0）]）
>>> poly.intersects（poly2）
 True 
>>> poly.equals（poly2）
 True 
  

我似乎遇到的问题是这两个多边形在它们的2D正交投影（相同的三角形）上是相等的，但是在不同的平面上（一个在Z = 1时，另一个在Z = 0时），但是很好地说它们是相等的并且相交。
$ b

有没有什么魔法可以让我们在3个维度上进行思考？我一直在使用谷歌搜索，但我目前看到的每个例子都只有两个维度。

根据<一个href =http://toblerity.github.com/shapely/manual.html#geometric-objects =nofollow noreferrer>匀称手动，它指出以下为z坐标平面的几何对象：

构建实例时可以使用第三个z坐标值，但对几何分析没有影响。所有操作都在xy平面上执行。 匀称可能不适合你。当然，您可以尝试将多边形的点作为列表并将其与其他多边形进行比较。然而，如果你想有一个可以处理z维度的Python几何库，你可以找到一些这里。

I'm working on determining relationships (boundary/interior intersections) between two 3D objects (triangular faces) and stumbled on shapely, which I am interested in using instead of implementing my own point/segment/ray/triangle intersection functions.

However, I'm running into the following problem:

    >>> from shapely.geometry import Polygon
    >>> poly = Polygon([(0,1,1),(1,-1,1),(-1,-1,1)])
    >>> poly2 = Polygon([(0,1,0),(1,-1,0),(-1,-1,0)])
    >>> poly.intersects(poly2)
    True
    >>> poly.equals(poly2)
    True

The problem I seem to be running into is that the two polygons are equal in their 2D orthogonal projections (same triangle), but in different planes (one's at Z=1, other at Z=0), but shapely is saying they're equal and intersect.

Is there some magic I'm missing to make shapely think in 3 dimensions? I've been googling, but every example I've seen so far is only in two dimensions.

解决方案

According to the Shapely manual, it states that the following for the z coordinate plane for geometric objects:

A third z coordinate value may be used when constructing instances, but has no effect on geometric analysis. All operations are performed in the x-y plane.

If your calculations require the z coordinate plane, then Shapely might not be for you. Of course, you could try to get the points of the polygon as a list and compare it to other polygons. However, if you want to have a Python geometric library that can handle the z dimension, you can find some here.

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