Reconstruction of 3D Trajectories for Performance Analysis in Table Tennis

A method of reconstructing the 3D trajectories of a table tennis ball is introduced, which was developed to solve the problem with conventional analysis in table tennis. There are several methods of reconstructing 2D ball trajectories or 3D trajectories of balls heavier than those in table tennis. However, these methods cannot be adopted to reconstruct the 3D trajectories of table tennis balls, because there are problems that are attributed to the dimensions of the trajectories and weight of the balls. The method proposed in this paper could reconstruct the 3D trajectories of a table tennis ball. The key feature of the method is that it approximates that a ball is traveling on tilted planes. This approximation makes reconstruction robust against failure to measure 3D ball positions. A system using two RGB cameras was developed based on the new method. The system experimentally demonstrated that it could provide accurate information for match analysis. A system using an RGB-D camera was then developed to optimize usability for practitioners. We experimentally demonstrated that the system could provide accurate information for service analysis.