排球影片分析—運動員軌跡之移動與跳躍的區別

Abstract

在球類運動分析中，多數研究著重於足球或籃球等，相較之下排球的分析研究偏少，本研究特別針對排球球員的運動軌跡，偵測其運動中跳躍的部分，可以提供此球員正確的移動軌跡，以及跳躍的資訊。本篇論文提出兩種跳躍軌跡分析方法，分別以軌跡垂直分量及消失點的特性，判斷球員移動軌跡中跳躍的部份。細部來說，我們利用背景模型切割前景區域，偵測出影像中欲追蹤之球員頭部位置，再藉由平面投影轉換，建構出球員在頂視平面上的軌跡，最後利用軌跡與消失點的特性，判斷軌跡中屬於跳躍的部分。而從實驗結果來看，軌跡中球員跳躍的部分都可有效的被偵測出來，並在移除跳躍軌跡後，呈現完整的球員移動軌跡。

In volleyball games, the analysis of players’ moving and jumping trajectories bring much tactical information. In this paper, we analyze volleyball videos to extract players’ trajectories and to identify the jumping parts of the extracted trajectories. The jumping parts can be determined via (i) vertical component analysis of trajectories and (ii) vanishing point-based collinear analysis of trajectories. Specifically, we first use background subtraction to segment foreground athletes and detect their head positions in an image sequence. The head positions are then transformed to top-view coordinates via homography transformation and form athletes’ trajectories. Finally, the method (i) and (ii) are applied to differentiate the moving and jumping parts of the trajectories. In our experiments, all the jumping parts of the trajectories are detected correctly, with moving trajectories of the athletes being displayed.