[SciPy-User] Strange results by scipy.spatial Delaunay

[Nils Wagner]

Hi all,

I tried to create a convex hull of a set of points distributed on a
cylindrical surface by the following
script. The needed input file coor.dat is attached.
How can I fix the problem with the distorted mesh (convex.png) ?

Nils



from scipy.spatial import Delaunay
import numpy as np

points = np.loadtxt('coor.dat',usecols =(1,2,3))
nid    = np.loadtxt('coor.dat',usecols=(0,))
m,n = points.shape
print 'Number of points m =', m

tri = Delaunay(points)
faces = []

for ia, ib, ic in tri.convex_hull:
     x1 = points[ia]
     x2 = points[ib]
     x3 = points[ic]
     area = 0.5*np.linalg.norm(np.cross(x2-x1,x1-x3))

     print 'Area of face', area
     faces.append(points[[ia, ib, ic]])

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.art3d import Poly3DCollection

fig = plt.figure()
ax = fig.gca(projection='3d')
items = Poly3DCollection(faces, facecolors=[(0, 0, 0, 0.1)])
ax.add_collection(items)
ax.scatter(points[:,0], points[:,1], points[:,2], 'o')
ax.legend(loc=0,shadow=True)
plt.show()
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