[Japanese | Thesis | Researches in Minoh Lab | Minoh Lab]

The camera control method that maximize communication of lecture information for video bandwidth

Distance learning based on computer network needs processes that shoot and stream video. Students in the lecture room where lecturer exists can directly get lecture information, such as motion of the lecturer, indication of the lecturer, and writing in a whiteboard. On the other hand, in a distance classroom, students can get lecture information only from lecture video. Therefore, the processes that shoot and stream video should make lecture information communicated well.

We call the set of controllable position of viewpoint, field of view, and direction of cameras "camerawork" here. Previous researches of shooting lecture video obtained video that has composition centering at objects providing lecture information, by controlling camerawork. Because they don't consider restriction of available bandwidth of network, they have problem that the restriction suppress special resolution of the video and obstruct communication of lecture information. Therefore, we aim to archive camera control that preserve special resolution as possible. We define rate of "communication of lecture information" as the product of "priority about composition" and sustaining ratio of special resolution. We get the camerawork that maximize the rate and control cameras following the camerawork. "Priority about composition" indicates whether objects providing lecture information at certain camerawork.

In this paper, we aim to we focus on that sustainable spatial resolution under the restriction varies if we change camerawork. To get preserving special resolution under restriction of available bandwidth of network at every camerawork, we calculated effect on video complexity from background lecture room and lecturer by prior measurement, and calculated reserving special resolution from available bandwidth and the complexity.

We did experiments in that we applied our method to camera control for multiple cameras placed on the lecture room. We showed our method maximized communication rate of lecture information for plural bandwidth in the experiments.

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