Discussion of photo anthropometrical method using three dimensional facial images

Personal identification in facial photographs is becoming increasingly important in the field of forensic science. Thanks to a recent development of the three-dimensional (3D) digital imaging technologies, we have applied this technology for personal identification in actual cases for over a decade. Besides using the 3D scanner for caseworks, the anthropometric data collection for the Japanese population is now ongoing using the commercially available 3D shape analysis software. In this study, we validated this software from the views of a posture standardization of the 3D faces, a reproducibility of the landmark positioning and an accuracy of their distances calculated. The latter two issues were examined by using standard cubic shapes obtained by 3D modeling using a computer aided design (CAD) software and by the 3D scanning for an actual cube model as well as by using 3D facial images. The results showed that the measurements were correctly established both in the standard Cubes and the 3D facial data even with several kinds of angles of the objects. The dispersion of the measurements can be reduced by displaying additional guidelines on the 3D facial image. From the results obtained, it was shown that the software we are currently using for anthropometry for the 3D face is applicable to both the caseworks and the anthropometric population study on large numbers of the 3D facial images.