Resum And Prospect

The method that has been presented is part of the process of the identification of unknown dead persons. Using this method, it is possible to develop a process that is completely digitized, from the reconstruction of the skull by joining the bone fragments up to the reconstruction of the surface of the face. This paper focuses on the digitized reconstruction of the skull (which could be looked at as a digitized 3D jigsaw puzzle), constituting the last missing component within the digitized process used for the identification of unknown dead persons. In order to support this new technology, a processing technique has been developed, based on the high-resolution 3D measurement of the fragments by SLT and using the functions of the CAD/CAM tools.

For the physical reconstruction of a skull, it is important to scrutinize the fractured pieces, to locate their matching parts, to test the matching parts using mechanical contact, and to verify the precision of the fit visually and metrically.

Figure 9.14

Digital skull for the facial reconstruction.

Figure 9.15

Facial reconstruction with skull and face shape.

All of these procedures are incorporated in the digitized processing techniques except for the mechanical contact. It is for this reason that techniques have been developed offering alternatives to this function. Apart from that, the digital processing technique offers an array of new functions that are not available using the classic procedure. The advantages of the digitized process are essentially due to the following factors:

■ absence of gravity (no gluing, no holding and support systems)

■ ability to penetrate the skull without causing destruction (joining the fragments in free order)

■ transparency of the skull (view of inner structures)

■ assembling of the fragments by direct visual control of the fracture surfaces

■ nondestructive measurement (measurement of depth and skull profile)

■ direct measurement of the precision of the fit using the fracture surfaces

■ fast creation of copies (no repetition of all processing steps).

Furthermore it is possible to evaluate objectively the reconstructed skull using the metric CAD functions. Evaluation criteria can be developed in order to

Figure 9.16

Facial reconstruction with skull and face shape from side.

Figure 9.16

Facial reconstruction with skull and face shape from side.

apply an objective measure for the evaluation of differences resulting from the comparison between variants of the skull.

At the end of the presented method, the digital skull can be integrated into different facial reconstruction processes (Vanezis 1989, Nelson 1998, Quatrehomme et al. 1997, Blanz 2000) (see as an example for a facial reconstruction Figures 9.14-9.16).

Parts of this method are also applicable for the reconstruction of the face, leaving open the possibility to develop objective criteria for a scientific comparison, using for example a series of measurements, average figures, and deviations from the standard. Overall, this method has the potential to contribute considerably to the advancement of digital methods used for the identification of unknown dead persons.

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