In the field of competitive swimming a quantitative evaluation of kinematic parameters is a valuable tool for coaches but also a labor intensive task. We present a system which is able to automate the extraction of many kinematic parameters such as stroke frequency, kick rates and stroke-specific intra-cyclic parameters from video footage of an athlete. While this task can in principle be solved by human pose estimation, the problem is exacerbated by permanently changing self-occlusion and severe noise caused by air bubbles, splashes, light reflection and light refraction. Current approaches for pose estimation are unable to provide the necessary localization precision under these conditions in order to enable accurate estimates of all desired kinematic parameters. In this paper we reduce the problem of kinematic parameter derivation to detecting key frames with a deep neural network human pose estimator. We show that we can correctly detect key frames with a precision which is on par with the human annotation performance. From the correctly located key frames, aforementioned parameters can be successfully inferred.
Dan Zecha, Christian Eggert, Rainer Lienhart, "Pose Estimation for Deriving Kinematic Parameters of Competitive Swimmers" in Proc. IS&T Int’l. Symp. on Electronic Imaging: Computer Vision Applications in Sports, 2017, pp 21 - 29, https://doi.org/10.2352/ISSN.2470-1173.2017.16.CVAS-345