Towards Auto-calibration of Smart Phones Using Orientation Sensors

In this paper, we address the problem of auto calibration of cameras which can rotate freely and change focal length, and we present an algorithm for finding the intrinsic parameters using only two images. We utilize orientation sensors found on many modern smart phones to help decompose the infinite homography into two equivalent upper triangular matrices based only on the intrinsic parameters. We account for small translations between views by calculating the homography based on correspondences on objects that are far away from the camera. We show results based on both real and synthetic data, and quantify the tolerance of our system to small translations and errors in the orientation sensors. Our results are comparable to other recent auto-calibration work while requiring only two images and being tolerant to some translation.