attachment:lic.py of Cookbook/LineIntegralConvolution - SciPy wiki dump (original) (raw)

1 import numpy as np 2 3 4 def lic_flow(vectors,len_pix=10): 5 vectors = np.asarray(vectors) 6 m,n,two = vectors.shape 7 if two!=2: 8 raise ValueError 9 10 result = np.zeros((2len_pix+1,m,n,2),dtype=np.int32) 11 center = len_pix 12 result[center,:,:,0] = np.arange(m)[:,np.newaxis] 13 result[center,:,:,1] = np.arange(n)[np.newaxis,:] 14 15 for i in range(m): 16 for j in range(n): 17 y = i 18 x = j 19 fx = 0.5 20 fy = 0.5 21 for k in range(len_pix): 22 vx, vy = vectors[y,x] 23 print x, y, vx, vy 24 if vx>=0: 25 tx = (1-fx)/vx 26 else: 27 tx = -fx/vx 28 if vy>=0: 29 ty = (1-fy)/vy 30 else: 31 ty = -fy/vy 32 if tx<ty: 33 print "x step" 34 if vx>0: 35 x+=1 36 fy+=vytx 37 fx=0. 38 else: 39 x-=1 40 fy+=vytx 41 fx=1. 42 else: 43 print "y step" 44 if vy>0: 45 y+=1 46 fx+=vxty 47 fy=0. 48 else: 49 y-=1 50 fx+=vx*ty 51 fy=1. 52 if x<0: x=0 53 if y<0: y=0 54 if x>=n: x=n-1 55 if y>=m: y=m-1 56 result[center+k+1,i,j,:] = y, x 57 58 59 60 return result

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