I have a raw floating array of 12 elements which contain an affine transformation matrix and I would like to map it to an Affine3f object.

The input floating point array actually stores the parameter in a row major sequence, while the Affine3f stores it in a column major format, if I am correct.

Is there nice Eigen recommended way to map such an array to the Affine3f object?

Have you tried to specify the parameter of the mapping as a RowMajor transform? According to the documentation, that option is available.

You may also need to use the AffineCompact mode for your 3×4 matrices.

Answered there: http://stackoverflow.com/questions/2416 ... n-affine3f