Compensation of measurement errors caused by glass refraction for photogrammetric plantar surface mapping

Abstract

Mapping the human plantar (sole) surface during movement using an optical imaging technique often necessitates the use of a stage made of transparent material so that the human subject's gait can be imaged in a natural way, without obstruction. This research investigates a technique to reduce glass refraction distortion in the captured 3D spatial data. Impurities in the glass produce outliers in the calculated distortion values which were detected using an automated slope gradient technique. A point-based moving averaging technique was utilised to determine the most appropriate distortion correction to replace the removed outliers. The results show that the empirical methods developed provide accurate glass refraction corrections for photogrammetric measurements, highlighted using the 3D foot plantar surface captured during various phases of a person's gait. © 2013 The Remote Sensing and Photogrammetry Society and John Wiley & Sons Ltd.