A 3D VIDEO TECHNIQUE FOR ANALYSIS OF SWIMMING IN A FLUME

Abstract

The photogrammetric evaluation of video recordings in a flume is complicated. Depending on the perspectives of cameras strong geometric distortions occur. Very short focal length, caused by lack of space, and transitions waterfair or waterfglassfair result in distortions in the recorded images. Using the photogrammetric evaluation we have to correct these geometric errors. The technological solution (recording setup, calibration, measurement in the images) for the swimming flume Hamburg is presented. Two lateral cameras, convergently geared, are applied to record the swimmer, simultaneously under and above the water. For the calibration of cameras a fine-meshed grid frame was placed several times in the object space. The measurements within the video image sequences were done analytically and simultaneously with special software.