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Geometric morphometric methods for three-dimensional virtual reconstruction of a fragmented cranium: The case of Angelo Poliziano

Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin (Impact Factor: 2.71). 04/2009; 123(4):333-44. DOI: 10.1007/s00414-009-0339-6
Source: PubMed

ABSTRACT

The process of forensic identification of missing individuals is frequently reliant on the superimposition of cranial remains onto an individual's picture and/or facial reconstruction. In the latter, the integrity of the skull or a cranium is an important factor in successful identification. Here, we recommend the usage of computerized virtual reconstruction and geometric morphometrics for the purposes of individual reconstruction and identification in forensics. We apply these methods to reconstruct a complete cranium from facial remains that allegedly belong to the famous Italian humanist of the fifteenth century, Angelo Poliziano (1454-1494). Raw data was obtained by computed tomography scans of the Poliziano face and a complete reference skull of a 37-year-old Italian male. Given that the amount of distortion of the facial remains is unknown, two reconstructions are proposed: The first calculates the average shape between the original and its reflection, and the second discards the less preserved left side of the cranium under the assumption that there is no deformation on the right. Both reconstructions perform well in the superimposition with the original preserved facial surface in a virtual environment. The reconstruction by means of averaging between the original and reflection yielded better results during the superimposition with portraits of Poliziano. We argue that the combination of computerized virtual reconstruction and geometric morphometric methods offers a number of advantages over traditional plastic reconstruction, among which are speed, reproducibility, easiness of manipulation when superimposing with pictures in virtual environment, and assumptions control.

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Available from: Stefano Benazzi
    • "Since it is essential to use a method based on a population as similar as possible with respect to the one under analysis, we used the soft tissue thickness table proposed by Helmer (1984) for male Caucasian subjects, taking into consideration the slender body of subject and the biological age suggested by the analysis of the remains (40–50 years). The same table had been previously used for the superimposition of the skull produced by geometric and morphometric techniques and the Italian humanist iconography, as described by Benazzi et al. (2009b) in order to perform an identification attempt. 46 pegs were cut at specific length according with the Helmer table and fixed in the corresponding anatomical land- mark. "
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    ABSTRACT: Frequently, identification of individuals is problematical due to the level of associated decomposition and even more when the skeletal remains are incomplete or fragmented. The identikit, which includes a sketch or a facial reconstruction, could assist investigators with determining the identity of the decedent. Similarly, in archeology and physical anthropology it gives a realistic appearance to a historical character known only through iconography. We examined the skull of Angelo Poliziano, an Italian humanist of the 15th century. Previously, his facial approximation was completed in clay according to the Manchester protocol and then a duplication was prepared in ultra-realistic materials. This technique returns a long lasting 3D model of the individual and provides the perception to be in front of a real person and, although expensive, applied in forensic context could it improve the recognition of the individual.
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    • "example, need a preliminary restoration before any further analyses or for exhibition (Fantini et al., 2005; Benazzi et al., 2010). In forensics, the recovery of the craniofacial skeleton in a fragmentary state could hamper any attempted facial reconstruction useful for positive identification (e.g., Wilkinson and Neave, 2003; Benazzi et al., 2009b). Finally, bone reconstruction presents a fundamental issue within several surgical disciplines, mainly in orthodontics and maxillofacial surgery (Mehta and Deschler, 2004; Young et al., 2007; Madsen et al., 2008; Baumann et al., 2010). "
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    • "In order to test the reliability of this procedure, the 3D model was previously superimposed to a fronto-lateral view of the reconstructed face. As suggested by Benazzi et al. (2009b) the pictures and the digital model of the skull were imported in Amira, and the orthogonal view was set. By means of dynamic translation, rotation and uniform scaling process, the skull was aligned either to the reconstructed face or to the portraits using virtual tissue depth markers (virtual pegs) defined on the digital skull to aid the process Table 1 List of landmarks and curves identified on the 3D digital models of the hemimandibles. "
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