  Extracting point correspondences from two or more views of a scene is a
fundamental computer vision problem with particular importance for relative
camera pose estimation and structure-from-motion. Existing local feature
matching approaches, trained with correspondence supervision on large-scale
datasets, obtain highly-accurate matches on the test sets. However, they do not
generalise well to new datasets with different characteristics to those they
were trained on, unlike classic feature extractors. Instead, they require
finetuning, which assumes that ground-truth correspondences or ground-truth
camera poses and 3D structure are available. We relax this assumption by
removing the requirement of 3D structure, e.g., depth maps or point clouds, and
only require camera pose information, which can be obtained from odometry. We
do so by replacing correspondence losses with epipolar losses, which encourage
putative matches to lie on the associated epipolar line. While weaker than
correspondence supervision, we observe that this cue is sufficient for
finetuning existing models on new data. We then further relax the assumption of
known camera poses by using pose estimates in a novel bootstrapping approach.
We evaluate on highly challenging datasets, including an indoor drone dataset
and an outdoor smartphone camera dataset, and obtain state-of-the-art results
without strong supervision.
