A Video Technique for Obtaining 3-D Coordinates in Alpine Skiing

A video technique to obtain 3-D data in an Alpine skiing competition was investigated. The flight and landing phases of a jump were recorded during the 1994 Olympic combined downhill race. A direct linear transformation (DLT) implementation was applied, which computes the DLT parameters for each video image of each camera separately. As a consequence, one is able to pan and tilt the cameras and zoom the lenses. The problem of distributing control points in the large object space could be solved satisfactorily. The method proved to be suitable for obtaining 3-D data with reasonable accuracy, which is even sufficient for inverse dynamics. The computed resultant knee joint forces and moments compare well with results reported by other authors.