Geometric Models of Rolling-Shutter Cameras

TL;DR

This paper develops a comprehensive geometric model for rolling-shutter cameras, analyzing how camera motion affects image projection and structure-from-motion, with approximations for various motion types.

Contribution

It introduces a general projection equation for rolling-shutter cameras and models specific motions, including fronto-parallel and screw motions, revealing their effects on geometry.

Findings

Rolling shutter causes systematic biases in projection estimation.

Modeling camera motion improves accuracy in structure-from-motion.

Approximate equations effectively capture motion effects on projections.

Abstract

Cameras with rolling shutters are becoming more common as low-power, low-cost CMOS sensors are being used more frequently in cameras. The rolling shutter means that not all scanlines are exposed over the same time interval. The effects of a rolling shutter are noticeable when either the camera or objects in the scene are moving and can lead to systematic biases in projection estimation. We develop a general projection equation for a rolling shutter camera and show how it is affected by different types of camera motion. In the case of fronto-parallel motion, we show how that camera can be modeled as an X-slit camera. We also develop approximate projection equations for a non-zero angular velocity about the optical axis and approximate the projection equation for a constant velocity screw motion. We demonstrate how the rolling shutter effects the projective geometry of the camera and in turn the structure-from-motion.