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How can I extract triangles from delaunay filter in mayavi?

I want to extract the triangles just like matplotlib does

import numpy as np
import matplotlib.delaunay as triang
from enthought.mayavi import mlab

x = np.array([0, 1, 2, 0, 1, 2, 0, 1, 2])
y = np.array([0, 0, 0, 1, 1, 1, 2, 2, 2])
z = np.zeros(9)
#matplotlib 
centers, edges, triangles_index, neig = triang.delaunay(x,y)

#mayavi
vtk_source = mlab.pipeline.scalar_scatter(x, y, z, figure=False)
delaunay =  mlab.pipeline.delaunay2d(vtk_source)

I want to extract the triangles from mayavi delaunay filter to obtain the variables @triangle_index and @centers (just like matplotlib)

The only thing I've found is this http://docs.enthought.com/mayavi/mayavi/auto/example_delaunay_graph.html

but only get the edges, and are codificated different than matplotlib

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1 回答 1

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获取三角形索引：

poly = delaunay.outputs[0]
tindex = poly.polys.data.to_array().reshape(-1, 4)[:, 1:]

poly是 PolyData 对象，poly.polys是存储索引信息的 CellArray 对象。有关 CellArray 的详细信息：http ://www.vtk.org/doc/nightly/html/classvtkCellArray.html

要获得每个外接圆的中心，您需要循环每个三角形并计算中心：

centers = []
for i in xrange(poly.number_of_cells):
    cell = poly.get_cell(i)
    points = cell.points.to_array()[:, :-1].tolist()
    center = [0, 0]
    points.append(center)
    cell.circumcircle(*points)
    centers.append(center)

centers = np.array(centers)

cell.circumcircle()是一个静态函数，所以你需要将三角形的所有点作为参数传递，中心数据将通过修改第四个参数返回。

这是完整的代码：

import numpy as np
from enthought.mayavi import mlab

x = np.array([0, 1, 2, 0, 1, 2, 0, 1, 2])
y = np.array([0, 0, 0, 1, 1, 1, 2, 2, 2])
z = np.zeros(9)

vtk_source = mlab.pipeline.scalar_scatter(x, y, z, figure=False)
delaunay =  mlab.pipeline.delaunay2d(vtk_source)

poly = delaunay.outputs[0]
tindex = poly.polys.data.to_array().reshape(-1, 4)[:, 1:]

centers = []
for i in xrange(poly.number_of_cells):
    cell = poly.get_cell(i)
    points = cell.points.to_array()[:, :-1].tolist()
    center = [0, 0]
    points.append(center)
    cell.circumcircle(*points)
    centers.append(center)

centers = np.array(centers)

print centers
print tindex

输出是：

[[ 1.5  0.5]
 [ 1.5  0.5]
 [ 0.5  1.5]
 [ 0.5  0.5]
 [ 0.5  0.5]
 [ 0.5  1.5]
 [ 1.5  1.5]
 [ 1.5  1.5]]
[[5 4 2]
 [4 1 2]
 [7 6 4]
 [4 3 1]
 [3 0 1]
 [6 3 4]
 [8 7 4]
 [8 4 5]]

结果可能与 不一样matplotlib.delaunay，因为有很多可能的解决方案。

于 2013-05-10T01:55:48.510 回答