[Insight-users] Get angle values from a 3D affine transform

[Yan Yang]

Hi All,

Could you have a look at my method, I am not sure if it is correct. Thanks in advance.

I am trying to extract angle information from a 3D affine transform, I want to know if I can do as the following steps.

1. Decompose the affine transform matrix (A) excluding translation using SVD (vnl_svd), get A = UWV,
    so the rotaiton matrix can be R = UV'.

2. Create an euler transform (E) using the rotation matrix, E->setMatrix( R ),

3. Calculate the three angles around axes by 
    angleX = E->GetAngleX()
    angleY = E->GetAngleY()
    angleZ = E->GetAngleZ()

Am I right?

By the way, should the rotation matrix R be vnl_matrix type? Does vnl_matrix support 3D?

Thanks,

Yan
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