Recording of Natural Head Position Using Stereophotogrammetry: A New Technique and Reliability Study. Hsung, TC; Lo, J; Li, TS; Cheung, LK.
Article: Recording of Natural Head Position Using Stereophotogrammetry: A New Technique and Reliability Study.
Authors: Tai-Chiu Hsung, PhD, BEng; John Lo, PhD, MDS, BDS; Tik-Shun Li, DMD, BSc‡, Lim-Kwong Cheung, PhD, BDS
Source: Journal of Oral and Maxillofacial Surgery (Online)
Date: April 2014
The purpose of this study was to develop a technique to record physical references and orient digital mesh models to a natural head position using stereophotogrammetry (SP). The first step was to record the digital mesh model of a hanging reference board placed at the capturing position of the SP machine. The board was aligned to true vertical using a plumb bob. It also was aligned with a laser plane parallel to a hanging mirror, which was located at the center of the machine. The parameter derived from the digital mesh model of the board was used to adjust the roll, pitch, and yaw of the subsequent captures of patients’ facial images. This information was valid until the next machine calibration. The board placement was repeatable, with standard deviations less than 0.1° for pitch and yaw angles and 0.15° for roll angles.