Very unclear names,
https://github.com/scipy/scipy-cookbook/blob/master/ipython/bundle_adjustment.ipynb

i don't understand the variable used in this code at all? for example:

points_2d with shape (n_observations, 2) contains measured 2-D coordinates of points projected on images in each observations.

in what image exactly are the coordinates given, assuming i see the point in multiple images, what coordinate do i enter exactly?