I calculated the 3x3 homography matrix and I need to get rotation, translation, shear and scale to use them as parameters in the windows8 media element attributes ?!
Tom Larkworthy
see https://math.stackexchange.com/questions/78137/decomposition-of-a-nonsquare-affine-matrix
def getComponents(normalised_homography):
'''((translationx, translationy), rotation, (scalex, scaley), shear)'''
a = normalised_homography[0,0]
b = normalised_homography[0,1]
c = normalised_homography[0,2]
d = normalised_homography[1,0]
e = normalised_homography[1,1]
f = normalised_homography[1,2]
p = math.sqrt(a*a + b*b)
r = (a*e - b*d)/(p)
q = (a*d+b*e)/(a*e - b*d)
translation = (c,f)
scale = (p,r)
shear = q
theta = math.atan2(b,a)
return (translation, theta, scale, shear)
来源：https://stackoverflow.com/questions/15420693/how-to-get-rotation-translation-shear-from-a-3x3-homography-matrix-in-c-sharp