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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