Validity and repeatability of a depth camera based surface imaging system for thigh volume measurement

Complex anthropometric measures, such as area and volume, can identify changes in body size and shape that are not detectable with traditional anthropometric measures of lengths, breadths, skinfolds and girths. However, taking these more complex measures with manual techniques (tape measurement and water displacement) is often unsuitable. Three dimensional (3D) surface imaging systems are quick and accurate alternatives to manual techniques but their use is restricted by cost, complexity and limited access. We have developed a novel low cost, accessible and portable 3D surface imaging system based on consumer depth cameras. The aim of this study was to determine the validity and repeatability of the system in the measurement of thigh volume. The thigh volumes of 36 participants were measured with the depth camera system and a high precision commercially available 3D surface imaging system (3dMD). The depth camera system used within this study is highly repeatable (technical error of measurement of < 1.0% intra-calibration and ~ 2.0% inter-calibration) but systematically overestimates (~6%) thigh volume when compared to the 3dMD system. This suggests poor agreement yet a close relationship, which once corrected can yield a usable thigh volume measurement. Keywords : Kinanthropometry, Anthropometry, Depth Camera, 3D Body Scanning, Surface Imaging.