INTRODUCTION: Camcorder-based 3D measurements are already a Standard procedure in the science of alpine skiing. Fixed cam to pan-tilt-zoom solutions are used. Joints and/or segments are detected with manual capturing, auto marker recognition, and lately, even image processing auto detection without markers. Unfortunately, none of these methods provides great accuracy, a long and wide measurement area, the quick preparation of measurements, and fast or immediate results at the same time. The GPS system and accelerometers have already been used in alpine skiing (Skalaud & Limpach, 2003). This paper introduces a new 3D measuring procedure based on the differential GPS system and an inertial suit that satisfies most needs. METHOD: A skier was wearing a Leica series 1200 DGPS system working at 20 Hz with an accuracy of 1 to 2 cm, and an Xsens technologies Moven mocap inertial suit. The inertial suit measured 23 body Segments (Fig. 1) in 6 DOD at 60 Hz and comprised 16 inertial motion trackers. Splines were used to interpolate the DGPS trajectory to 60 Hz. This trajectory represented a reference point of the neck in the human model measured from the inertial suit. We recorded five runs performed by two regional team racers through Figure 1, 3D animation. a training course setup. All runs were also recorded with a miniDV camcorder. The video was transformed to 60 Hz and synchronized with the recorded data. The data from DGPS and the inertial suit were joined together and reformatted for use in the KinSki 3.1 analyzing system (Supej et al., 2005) in Matlab. RESULTS: Skiers' runs were recorded through a whole ski run. An example of hip and knee angulation angles is shown in Fig. 2. DISCUSSION: The measurements preparation and analysis time is very short in comparison with camcorder-based techniques. The measurement area is several times larger. Results have hight(s) reliability due to the accuracy of the reference point Segments' angular velocities, accelerations and angles are expected to be more accurate than in camcorder techniques. Joint locations are not accurate in this version, CONCLUSION: This study and the lest measurements show that the new proposed measuring procedure is suitable for alpine skiing and has several advantages over established camcorder techniques.
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