VALIDATION OF A THREE-DIMENSIONAL FILM ANALYSIS TECHNIQUE

Abstract

Biomechanical studies have moved into more flexible film analysis techniques with the onset of computer technology. A number of these techniques have allowed for the analysis of sport movements in three dimensions instead of the more restricted two-dimensional setting (Anderson, 1970; Bergemann. 1974; Martin & Pongratz, 1974; Miller & Petak, 1973; and VanGheluwe, 1974). Methods have been developed that use three-dimensional film analysis but require special metric cameras (Ayoub, Ayoub, & Bamsey, 1970; Bullock, 1974; Bullock & Harley, 1972; Lippert, Hussain, & Veress. 1974). A technique that utilizes nonmetric cameras was developed by Abdel-Aziz and Karara (1971) for still cameras, and later adapted for use with high speed cameras. This method is referred to as direct linear transfornation (DLT). The DLT process allows for data collected from two different cameras to be merged into three-dimensional output (Shapiro, 1980). A computer program written by Marzan and Karara (1975) performs the complicated mathematical equations associated with DLT. Verification of this program was necessary because of program changes made when adapting it from one computer system to another.