# How to interpret the rotation matrices of the homographybasedestimator?

Good morning,

I have question regarding OpenCV's homographyBasedEstimator. While reading the source code I found out that it determines a set of transformations, which relate every input image to a reference image by multiplying the homographies from the pairwise matching step. Before the multiplication each homography is normalized (R = K_from.inv() * pairwise_matches[pair_idx].H.inv() * K_to).

What I do not fully understand is how to interpret the rotations returned by this method.

1. Are they just homographies which relate each image to the reference image?
2. Or can they be interpreted as the camera's pose, i.e., its external orientation, because they are used as initial guess for the subsequent bundle adjustment?