Despite the expected synergistic effects, augmented and virtual reality (AR and VR, respectively) technologies still tend to be discrete entities. In this paper, we describe our effort to enable both AR and VR users to share the same physical geometric space. The geometric transformation between two world spaces, defined separately by AR and VR systems, are estimated using a specially designed tracking board. Once initially obtained, the transformation will allow users to collaborate with each other within an integrated physical environment while making the best use of both AR and VR technologies.

The simple frame-to-frame tracking used for dense visual odometry is computationally efficient, but regarded as rather numerically unstable, easily entailing a rapid accumulation of pose estimation errors. In this paper, we show that a cost-efficient extension of the frame-to-frame tracking can significantly improve the accuracy of estimated camera poses. In particular, we propose to use a multi-level pose error correction scheme in which the camera poses are reestimated only when necessary against a few adaptively selected reference frames. Unlike the recent successful camera tracking methods that mostly rely on the extra computing time and/or memory space for performing global pose optimization and/or keeping accumulated models, the extended frame-to-frame tracking requires to keep only a few recent frames to improve the accuracy. Thus, the resulting visual odometry scheme is lightweight in terms of both time and space complexity, offering a compact implementation on mobile devices, which do not still have sufficient computing power to run such complicated methods.