Assessment of Computer-assisted Comparison between 3D and 2D Facial Images.

The face-to-face superimposition was experimentally performed to assess the reliability of the facial image comparison with the computer-assisted facial image identification system. For evaluating the match of the 3D and 2D facial images of the same person, the 3D facial image obtained from 25 examinees was compared to the 2D oblique facial image of the same examinees ten times, yielding 250 superimpositions. In the case of the different person, the 3D facial images of 25 examinees were each compared to the 2D facial images of other 24 examinees, yielding 600 superimpositions. The average distance obtained from the reciprocal point-to-point differences on sixteen anthropometrical points of the 3D and 2D images was used as a matching criterion.   The results showed that the measuring system for the reciprocal point-to-point differences on the superimposition image was reproducible. The ranges of the average distance were 1.4-3.3 for the same person and 2.6-7.0 for a different person, respectively. The average distance and percentage error at the FP/FN crossover point were 3.1 and 4.2%. In this experiment, it was suggested that the facial image comparison using the reciprocal points matching was reliable when the threshold of the average distance was 2.5.