I am writing a bachelor's diploma on vSLAM. I learned and programmed EKF-SLAM like it's written in MonoSLAM paper, and I was going to write, that I can't use KF and have to use EKF because of non-linearity of observation function, but wait, how is it possible, if everything is linear?!
I understand, that if I store direction of a camera in form of axis-angle vector or quaternion then there will be something non-linear, but what if I will store it directly as values of rotation matrix? Then my observation function is just going to be a multiplication of matrices, which is a linear operator, and therefore linear. Am I wrong?