EG2018

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https://diglib.eg.org/handle/10.2312/2632158

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Browsing EG2018 by Subject "Camera calibration"

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    Accurate Control of a Pan-tilt System Based on Parameterization of Rotational Motion
    (The Eurographics Association, 2018) Byun, JungHyun; Chae, SeungHo; Han, TackDon; Diamanti, Olga and Vaxman, Amir
    A pan-tilt camera system has been adopted by a variety of fields since it can cover a wide range of region compared to a single fixated camera setup. Yet many studies rely on factory-assembled and calibrated platforms and assume an ideal rotation where rotation axes are perfectly aligned with the optical axis of the local camera. However, in a user-created setup where a pan-tilting mechanism is arbitrarily assembled, the kinematic configurations may be inaccurate or unknown, violating ideal rotation. These discrepancies in the model with the real physics result in erroneous servo manipulation of the pan-tilting system. In this paper, we propose an accurate control mechanism for arbitrarily-assembled pan-tilt camera systems. The proposed method formulates pan-tilt rotations as motion along great circle trajectories and calibrates its model parameters, such as positions and vectors of rotation axes, in 3D space. Then, one can accurately servo pan-tilt rotations with pose estimation from inverse kinematics of their transformation. The comparative experiment demonstrates out-performance of the proposed method, in terms of accurately localizing target points in world coordinates, after being rotated from their captured camera frames.
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    Teaching Spatial Augmented Reality: a Practical Assignment for Large Audiences
    (The Eurographics Association, 2018) Ridel, Brett; Reuter, Patrick; Couture, Nadine; Post, Frits and Žára, Jirí
    We present a new methodology to teach spatial augmented reality in a practical assignment to large audiences. Our approach does not require specific equipment such as video projectors while teaching the principal topics and difficulties involved in spatial augmented reality applications, and especially calibration and tracking. The key idea is to set up a scene graph consisting of a 3D scene with a simulated projector that "projects" content onto a virtual representation of the real-world object. For illustrating the calibration, we simplify the intrinsic parameters to using the field of view, both for the camera and the projector. For illustrating the tracking, instead of relying on specific hardware or software, we exploit the relative transformations in the scene graph. We implemented our teaching methodology in Unity3D and tested it within a three-hour assignment to 24 and 20 master-level students in two consecutive years. We show the positive feedback that we received and discuss our plans for further improvement.