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Capturing the 3D motion of ski jumpers. Trip to Bonn (13-16 Nov 2005) Atle Nes. Faculty of Informatics and e-Learning Trondheim University College. Project description. Goal: Design a multiple video camera system that can be used to capture and study the motion of ski jumpers in 3D.
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Capturing the 3D motion of ski jumpers Trip to Bonn (13-16 Nov 2005) Atle Nes Faculty of Informatics and e-Learning Trondheim University College
Project description • Goal: Design a multiple video camera system that can be used to capture and study the motion of ski jumpers in 3D. • Task: Want to give feedback to the ski jumpers that can help them to improve their jumping skills.
How? • Multiple video cameras placed in a ski jumping hill are used to capture image sequences of a ski jump from different angles synchronously.
Image Acquisition(capture video ofski jumper) Motion analysis (select & interpret motion data) Video Images Vizualization(relate 3d points to ski jump model) Image Processing(detect, identify &track points) Photogrammetry(2d 3d mapping) 2D ImageCoordinates 3D ObjectCoordinates
Camera equipment 3x AVT Marlin cameras: • IEEE-1394 FireWire DCAM • Resolution 640x480 x 30 fps x 8 bit grayscale • 3x 9 MB/s = 27 MB/s • Changeable lenses
Camera equipment (cont.) Operating long distances: • 3x 400 m optical fibre extension for firewire (signals and data) • 3x 25 m power cables • 600 m synchronization cable PC: 2.4 GHz Intel P4, 4x Firewire buses, 2GB RAM (buffered), 2x WD Raptor 10.000 rpm in RAID-0 (harddisk)
Camera setup Synch pulse Video data + Control signals
Video processing • Points are automatically detected, identified and tracked over time and accross different views. • Reflective markers are placed on the ski jumpers suit, helmet and skies.
Photogrammetry • Matching corresponding feature points from two or more cameras allows us to calculate the exact position of that feature point in 3D. • Assumes that one knows the position and viewing direction of each camera.
Camera calibration • Measure exact coordinates in the hill using differential GPS and land survey robot station. • Place visible markers at those spots and estimate a geometry (relationship between 2D and 3D). • Reconstruction is then trivial.
Visualization • Feature points are connected back onto a 3D model of the ski jumper. • Allowed to be moved and controlled in a large static model of the ski jump arena.
Conclusion • A lot of challenging topics • Remains to be seen how well the ski jumpers will perform based on this kind of feedback.