I observe a scene with two cameras, c1 and c2, that produce two images i1 and i2, respectively. What I ultimately want to do is to use information of image i1 and image2 simultaneously, e.g., for object detection.
As far as I understand it, I would not be required to find the intrinsic parameters of c1 and c2, also I do not need to know their relative position and rotation if I want to rectify i1 and i2. I can "simply" calculate F from a set of corresponding points - with no explicit relation in 3D of the points (like known distances). Which disadvantages would that have for me? I would not be able to do 3D reconstruction then, correct? But apart from that, there is no difference?
Or, asked differently, for rectification I do not need the intrinsic parameters. I only need them to do 3D reconstruction? What are the intrinsic parameters good for?