Reconstruction accuracy in underwater three-dimensional kinematic analysis

Summary Accuracy of kinematic data is of decisive importance in motion analysis particularly when they are to be used for the calculation of kinetic parameters, like the propulsive forces in swimming. The present study investigated the accuracy of underwater three-dimensional (3-D) kinematic analysi...

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Bibliographic Details
Published in:Journal of science and medicine in sport 2008-04, Vol.11 (2), p.90-95
Main Authors: Gourgoulis, Vassilios, Aggeloussis, Nikolaos, Kasimatis, Panagiotis, Vezos, Nikolaos, Boli, Alexia, Mavromatis, Giorgos
Format: Article
Language:English
Subjects:
Accuracy
Biomechanical Phenomena
Cameras
Humans
Image Processing, Computer-Assisted
Imaging, Three-Dimensional
Kinematics
Physical Medicine and Rehabilitation
Reproducibility of Results
Sports Medicine
Studies
Swimming
Three-dimensional
Videotape Recording
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Summary:Summary Accuracy of kinematic data is of decisive importance in motion analysis particularly when they are to be used for the calculation of kinetic parameters, like the propulsive forces in swimming. The present study investigated the accuracy of underwater three-dimensional (3-D) kinematic analysis using periscope systems and calibration volumes with different size. Two analogue cameras (60 Hz) were used to record the images, along with two stationary periscope systems for the underwater recordings. The calibration of the recording space was performed using two different-sized calibration frames. The reconstruction accuracy was determined in static and dynamic conditions, both under water and out of the water. In static conditions, the reconstruction accuracy was determined by calculating the root mean square (RMS) error for the reconstruction of eight validation points on the calibration frames, and in dynamic conditions it was determined by the percentage of RMS error of the reconstructed length of a moving rod. The results revealed that in static conditions the RMS error was greater during underwater analysis, due to refraction, and it was increased particularly in the longitudinal axis as the dimensions of the calibration volume were increased. The reconstruction errors observed during underwater recordings with both calibration volumes (transverse axis, 1.61–2.35 mm; longitudinal, 2.99–4.64 mm; vertical, 2.83–2.59 mm) may be considered suitable for three-dimensional kinematic analysis of swimming.
ISSN:1440-2440
1878-1861
DOI:10.1016/j.jsams.2007.02.010