Analysis of the variability of facial landmarks in a forensic scenario

This paper reports an study of the variability of facial landmarks in a forensic scenario. This variability is affected by two factors: on the one hand, the precision in which the landmarks are tagged (manually or automatically), and on the other hand some other variability factors such as the pose, expression, occlusions, etc. For this study, a mugshot database of 50 persons has been collected following the procedure used by the Spanish Guardia Civil. Mugshots are taken with three distances between the persons and the camera (3, 2, 1 meters) showing the full body, the upper body and the face respectively, obtaining in total 1200 images. 21 facial landmarks are defined and the database was manually tagged imitating the procedure followed by a forensic examiner. This paper analyses the facial landmarking variability for the three distances considered, and also considering the differences obtained for male and female. Results show that landmarks located in the outer part of the face (highest end of the head, ears and chin) present a higher level of variability compared to the landmarks located the inner face (eye region, and nose). Regarding the gender, the landmarks placed in the outer part of the face present a higher level of variability for women compared to men.