Degeneracies in Rolling Shutter SfM

We address the problem of Structure from Motion (SfM) with rolling shutter cameras. We first show that many common camera configurations, e.g. cameras with parallel readout directions, become critical and allow for a large class of ambiguities in multi-view reconstruction. We provide mathematical analysis for one, two and some multiview cases and verify it by synthetic experiments. Next, we demonstrate that bundle adjustment with rolling shutter cameras, which are close to critical configurations, may still produce drastically deformed reconstructions. Finally, we provide practical recipes how to photograph with rolling shutter cameras to avoid scene deformations in SfM. We evaluate the recipes and provide a quantitative analysis of their performance in real experiments. Our results show how to reconstruct correct 3D models with rolling shutter cameras.