The Measurement of Three-Dimensional Body Movements by the Use of Photogrammetry

Abstract

Stereophotogrammetry is evaluated as a method of studying dynamic posture, the particular activity used during experimentation being the depression of a foot pedal, whose position and resistance was set to produce large-range trunk and pelvic movements in three dimensions. A description is given of the experimental procedure which was followed in order to measure the extent and direction of movements in three-dimensional space, to record velocities and to analyse the sequence and. pattern of motion in the whole body. The procedures for acquiring, recording and reducing data, using stereophotography, stercoplotting and computation, are explained. An evaluation of the accuracy attained indicates that, with this particular equipment and geometrical configuration, measurements of small movements, of the order of 0-3 m, have a standard error of 0.6mm even when the subject moves at a rate of up to 30 cm per sec. Suggestions are given for possible improvements which could be made to the procedure and for the application of this method of study to investigations in the field of ergonomics.