Two-Camera Synchronization and Trajectory Reconstruction for a Touch Screen Usability Experiment

This paper considers the usability of stereoscopic 3D touch displays. For this purpose extensive subjective experiments were carried out and the hand movements of test subjects were recorded using a two-camera setup consisting of a high-speed camera and a standard RGB video camera with different viewing angles. This produced a large amount of video data that is very laborious to analyze manually which motivates the development of automated methods. In this paper, we propose a method for automatic video synchronization for the two cameras to enable 3D trajectory reconstruction. This together with proper finger tracking and trajectory processing techniques form a fully automated measurement framework for hand movements. We evaluated the proposed method with a large amount of hand movement videos and demonstrated its accuracy on 3D trajectory reconstruction. Finally, we computed a set of hand trajectory features from the data and show that certain features, such as the mean and maximum velocity differ statistically significantly between different target object disparity categories. With small modifications, the framework can be utilized in other similar HCI studies.