Leipner Anja, Obertová Zuzana, Wermuth Martin, Thali Michael, Ottiker Thomas, Sieberth Till
Zurich Forensic Science Institute, Zeughausstrasse 11, CH-8004 Zurich, Switzerland.
Zurich Forensic Science Institute, Zeughausstrasse 11, CH-8004 Zurich, Switzerland.
Forensic Sci Int. 2019 Jul;300:6-12. doi: 10.1016/j.forsciint.2019.04.015. Epub 2019 Apr 22.
No human face is like another, not even in monozygotic twins, which makes the face one of the most individualizing characteristic. It is for this reason that the human face is commonly used for identification purposes and police officers take portrait photographs of arrested persons, so-called mug shots. The disadvantage of these 2D mug shots is that the perspective, in which they are taken (usually frontal and lateral-right, left or both), cannot be changed after acquisition, thus limiting a potential comparison between a mug shot and surveillance footage or other visual recordings. Documenting a face in 3D would reduce this problem as it allows adjusting the perspective of the face for image comparisons depending on the needs of the investigator. We have developed a 3D mug shot system containing 26 digital single-lens reflex cameras arranged semi-circularly in a 200° arc with a 1.46 m radius around a height-adjustable chair. We generated photogrammetric models of a test person's face captured by the mug shot system using three different focal lengths settings as well as 3D models of the same face with GOM Atos Triple Scan and Artec Space Spider. The 3D models were then analysed regarding the visibility of detailed morphological features in different regions of the face compared to 2D mug shots. Our results showed that our 3D mug shot system with its photogrammetric documentation generates 3D models with comparable surface quality to Artec-generated models, or even better quality, compared to GOM-generated models. The results of the morphological assessment were affected by the focal length and availability of texture information. In conclusion, the 3D mug shot system is a fast and efficient tool to generate 3D models of the face and may be used in addition to 2D photographs for the purpose of visual forensic identification based on images.
没有哪两张人脸是完全一样的，即使是同卵双胞胎也不例外，这使得人脸成为最具个体辨识度的特征之一。正因如此，人脸常被用于身份识别，警察会为被捕人员拍摄人像照片，即所谓的面部照片。这些二维面部照片的缺点在于，拍摄角度（通常为正面和右侧、左侧或双侧）在拍摄后无法改变，从而限制了面部照片与监控录像或其他视觉记录之间的潜在比对。以三维方式记录人脸可以减少这一问题，因为它能根据调查人员的需求调整人脸视角以进行图像比对。我们开发了一种三维面部照片系统，该系统包含26台数码单反相机，围绕一把高度可调节的椅子呈半圆形排列，形成一个半径为1.46米、弧度为200°的弧形。我们使用三种不同的焦距设置，通过该面部照片系统生成了一名测试人员面部的摄影测量模型，同时还使用GOM Atos Triple Scan和Artec Space Spider生成了同一张脸的三维模型。然后，将这些三维模型与二维面部照片进行比较，分析面部不同区域详细形态特征的可见性。我们的结果表明，我们的三维面部照片系统及其摄影测量记录生成的三维模型，与Artec生成的模型相比，具有可比的表面质量，与GOM生成的模型相比，质量甚至更好。形态学评估的结果受焦距和纹理信息可用性的影响。总之，三维面部照片系统是一种快速高效的工具，可用于生成人脸的三维模型，除二维照片外，还可用于基于图像的视觉法医鉴定。
