I'm trying to implement the OpenCV fisheye camera model in OpenGL shader, so I checked the OpenCV document.
I don't understand what "α" mean in this function:
u=fx(x′+αy′)+cx
It is for skew.
The following can be seen in the explanation of the argument of fisheye::calibrate
fisheye::CALIB_FIX_SKEW Skew coefficient (alpha) is set to zero and stay zero.