Mercurial > hg > orthanc-stone

annotate Resources/Computations/ComputeShearParameters.py @ 191:46cb2eedc2e0 wasm

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ShearWarpProjectiveTransform
author Sebastien Jodogne <s.jodogne@gmail.com>
date Fri, 16 Mar 2018 15:01:52 +0100
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1 #!/usr/bin/python
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2
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3 from sympy import *
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4 import pprint
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5
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6 init_printing(use_unicode=True)
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7
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8 s13, s23, s43 = symbols('s13 s23 s43')
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9 x, y, z, w = symbols('x y z w')
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11 A = Matrix([[ 1, 0, s13, 0 ],
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12 [ 0, 1, s23, 0 ],
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13 [ 0, 0, 1, 0 ],
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14 [ 0, 0, s43, 1 ]])
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16 print('\nLacroute\'s shear matrix (A.14) is:')
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17 pprint.pprint(A)
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18
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19 # At this point, we can write "print(A*p)". However, we don't care
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20 # about the output "z" axis, as it is fixed. So we delete the 3rd row
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21 # of A.
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23 A.row_del(2)
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25 p = Matrix([ x, y, z, 1 ])
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27 v = A*p
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28 print('\nAction of Lacroute\'s shear matrix on plane z (taking w=1):\n%s\n' % v)
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29
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30 print('Scaling = %s' % (1/v[2]))
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31 print('Offset X = %s' % (v[0]/v[2]).subs(x, 0))
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32 print('Offset Y = %s' % (v[1]/v[2]).subs(y, 0))