The Accuracy of Photogrammetric Measurements Employed in the Analysis of Facial Morphology

In the past few decades, measurements from standard photographs of the face (photogrammetry) have been widely used. The present clinical investigation of 18 young adults has been carried out to determine whether anthropometric measurements taken from standard photographs are as accurate as those taken on the living face. The purpose of this study was also to establish the maximum number of valid photographic measurements that can be obtained from the various areas of the head and face, as compared with the same measurements calculated directly from the face of the same subject. Furthermore, the objective was to compare our results with those from other studies reported in the literature and to search for specific factors that might be the cause of errors in photogrammetry. Twenty-six soft-tissue anatomical landmarks were identified on the face of each individual. Thirty linear measurements obtained directly from the subjects were recorded, and later on statistically compared to duplicate measurements taken from developed life-size frontal and left-lateral prints of the same people. Differences between the groups (direct and indirect) were determined for each linear measurement by performing Paired-Sample t-Tests thereby, determining the validity of each indirect linear value. The results of this study demonstrated that 83.3% of the total amount of linear measurements determined directly from the living subjects, can be reproduced with some degree of accuracy (P\u3e0.002) on a frontal or lateral standardized photographic print depending on the specific linear distance being assessed. The area of the orbits yielded the highest percentage of accurate indirect measurements, followed by the area of the lips and the mouth; next was the nose, and last, the area of the face. When comparing the two views photographed of each individual, it was found that in general, lateral prints offer a greater amount of accurate measurements than frontal prints