The components of variability in volumetric distribution determination by stereophotogrammetry

Abstract

The purpose for this investigation was to determine the contribution of selected components to the total variability of body volume in human subjects using biostereometric measurement. The objectives were to: (1) determine the contribution of intra-individual variation in body volume distribution using stereophotogrammetry, and (2) determine the contribution of measurement error variation in body volume distribution measurement using stereophotogrammetry. Procedures. Collection of data for this study entailed the use of stereophotogrammetry for determination of the volume distribution in six male subjects for eight consecutive days. The stereophotogrammetric technique of data acquisition provided simultaneous recording of the front and rear stereopairs of each subject. Two sets of Hasselblad Super Wide Angle Cameras linked by electro-mechanical shutter releases and synchronized with flash projections were utilized. The data were reduced on a Kern PG-2 stereoplotting instrument for the purpose of obtaining Cartesian coordinates that represented points lying on the surface of a precisely scaled stereomodel of the subject's body. The coordinates were read in parallel cross-sections approximately 5.08 centimeters apart and perpendicular to the long axis of the body. The reduction output provided suitable input to a digital computer programmed to calculate the body volume distribution. The volume distribution output was examined for variation over the eight day period in the total body, the right leg and a ten centimeter segment of the right leg. The within subject variation was partitioned into measurement error variation and intra-individual variation..