YEADON, M.R., 1990. The simulation of aerial movement—I. The determination of orientation angles from film data. Journal of Biomechanics, 23 (1), pp. 59-66.
Quantitative mechanical analyses of human movement require the time histories of the angles
which specify body configuration and orientation. When these angles are obtained from a filmed
performance they may be used to evaluate the accuracy of a simulation model. This paper presents
a method of determining orientation angles and their rates of change from film data. The stages
used comprise the synchronisation of data obtained from two camera views, the determination of
three-dimensional coordinates of joint centres, the calculation of an angle from a sequence of sine
and cosine values and the curve fitting of angles using quintic splines. For each stage, other possible
approaches are discussed. Original procedures are presented for obtaining individual error estimates
of both the film data and the calculated angles to permit the automatic fitting of quintic splines
for interpolation and differentiation and for deriving the time history of an angle as a continuous
function from a sequence of sine and cosine values. The method is applied to a forward somersault
with 1 1
2 twists and the average error estimate of 17 orientation angles is obtained as 2.1 degrees.