3D VIDEO TECHNIQUE FOR THE ANALYSIS OF ROWING IN A NATURAL ENVIRONMENT
Keywords: rowing, 3D, videogrammetry
AbstractINTRODUCTION: The dominating methods for biomechanical analyses of rowing are the use of a) measuring vessels to determine the forces on the oar and the board on which the feet are supported and b) video analysis to deduce split times for a race. Using these procedures, it is not possible to gain information on body movements which are of special interest in team boats. There is a paucity of research literature related to this problem. The purpose of this study was to developed video procedures which make the full-format recording of spacious rowing cycles possible by solving complicated problems of calibration. METHODS: Two new approaches were used to solve the problem of acquiring 3D kinematic information on rowing in a natural environment. The first solution was focused on recordings during competitions. Two video cameras with freely chosen positions on the banks were panned and zoomed when recording the boat, while calibration information was gained using measured buoys and the position of the cameras. A second solution focused on the training environment using recordings of two video cameras on a catamaran. The recordings of both cameras are mixed onto only one video-tape, making the video analysis much easier. Calibration for this procedure is only done once, using a solid calibration frame on the bank with the same arrangement of the cameras. To exactly digitize hidden body landmarks, the procedure presented by Drenk (1996) was employed. RESULTS: It became possible to evaluate the synchronization of body movements for team boats in natural environments. Sometimes, unexpected distinct transverse movements of the boat during the rowing cycle were monitored. As usual, body angles and their temporal course, as well as the impulse transformation onto the boat, could be calculated. CONCLUSIONS: Movement analyses in rowing in a natural environment could be performed successfully using new calibration and recording procedures. The analysis of video recordings became much simpler, since the recordings of both cameras could be analyzed simultaneously. Inclinations of the boat line up to 16° relative to the direct line were found. These were caused by minimal asymmetrical rowing motions. REFERENCES: Drenk, V. (1996). A Measuring Method for 3D-Analysis of Footpositions in Figure skating. In J. M. C. S. Abrantes (Ed.), ISBS Proceedings, (pp. 159-161). Lisboa: Edicoes FMH.
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