Hi,

The bug is in orb.cpp/IC_Angle, instead of
@return return fastAtan2((float)m_01, (float)m_10);@
(float)m_10);
it should be:
@return return fastAtan2(-(float)m_01, (float)m_10);@ (float)m_10);
because the axis system is undirect (y toward the bottom).

It's clear on the attached picture, the second image is the same as the first one but rotated.
Notice that if you take the symetric angle for both then it's OK.

I tried to correct it but then it doesn't match anymore, you surely learned the bug and did a trick,
but the angle is still wrong.

Or drawKeyPoint is wrong and should represent the angle in the undirect sens (??!!)

Thank's for your work.
Mathieu.