Up side down align result

[cannguyen275]

Hi,

I sometimes receive up-side-down aligned face by using this code.
Here is some sample:

Align code in python (scikit-image version) works perfectly. I don't know what wrong with c++ version.
Can you pls help to fix it?

Thanks,

[LamForest]

This Cpp code is an exact re-implementation of similarity transform in skimage.
However, when the SVD of a matrix is not unique. cv::SVD and np.SVD give different results This can led to your problem.