mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-27 17:31:50 +08:00
Almar Klein
73 lines
2.3 KiB
Python
73 lines
2.3 KiB
Python
"""
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Script to show the results of the two marching cubes algorithms on different
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data.
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"""
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import time
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import numpy as np
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import visvis as vv
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from skimage.measure import marching_cubes_classic, marching_cubes_lewiner
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from skimage.draw import ellipsoid
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# Create test volume
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SELECT = 3
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gradient_dir = 'descent' # ascent or descent
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if SELECT == 1:
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# Medical data
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vol = vv.volread('stent')
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isovalue = 800
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elif SELECT == 2:
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# Blocky data
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vol = vv.aVolume(20, 128) # Different every time
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isovalue = 0.2
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elif SELECT == 3:
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# Generate two donuts using a formula by Thomas Lewiner
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n = 48
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a, b = 2.5/n, -1.25
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isovalue = 0.0
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#
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vol = np.empty((n,n,n), 'float32')
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for iz in range(vol.shape[0]):
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for iy in range(vol.shape[1]):
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for ix in range(vol.shape[2]):
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z, y, x = float(iz)*a+b, float(iy)*a+b, float(ix)*a+b
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vol[iz,iy,ix] = ( (
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(8*x)**2 + (8*y-2)**2 + (8*z)**2 + 16 - 1.85*1.85 ) * ( (8*x)**2 +
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(8*y-2)**2 + (8*z)**2 + 16 - 1.85*1.85 ) - 64 * ( (8*x)**2 + (8*y-2)**2 )
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) * ( ( (8*x)**2 + ((8*y-2)+4)*((8*y-2)+4) + (8*z)**2 + 16 - 1.85*1.85 )
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* ( (8*x)**2 + ((8*y-2)+4)*((8*y-2)+4) + (8*z)**2 + 16 - 1.85*1.85 ) -
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64 * ( ((8*y-2)+4)*((8*y-2)+4) + (8*z)**2
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) ) + 1025
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# Uncommenting the line below will yield different results for classic MC
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#vol = -vol
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elif SELECT == 4:
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vol = ellipsoid(4, 3, 2, levelset=True)
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isovalue = 0
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# Get surface meshes
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t0 = time.time()
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vertices1, faces1, *_ = marching_cubes_lewiner(vol, isovalue, gradient_direction=gradient_dir, use_classic=False)
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print('finding surface lewiner took %1.0f ms' % (1000*(time.time()-t0)) )
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t0 = time.time()
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vertices2, faces2, *_ = marching_cubes_classic(vol, isovalue, gradient_direction=gradient_dir)
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print('finding surface classic took %1.0f ms' % (1000*(time.time()-t0)) )
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# Show
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vv.figure(1); vv.clf()
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a1 = vv.subplot(121); m1 = vv.mesh(np.fliplr(vertices1), faces1)
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a2 = vv.subplot(122); m2 = vv.mesh(np.fliplr(vertices2), faces2)
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a1.camera = a2.camera
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# visvis uses right-hand rule, gradient_direction param uses left-hand rule
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m1.cullFaces = m2.cullFaces = 'front' # None, front or back
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vv.use().Run()
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