S. Kottner et al., "Multispectral 3D Whole-Body Imaging of Dressed and Undressed Bodies in Combination with Post-Mortem X-Ray Computed Tomography", Proc. of 3DBODY.TECH 2021 - 12th Int. Conf. and Exh. on 3D Body Scanning and Processing Technologies, Lugano, Switzerland, 19-20 Oct. 2021, #24, https://doi.org/10.15221/21.24.

Title:

Multispectral 3D Whole-Body Imaging of Dressed and Undressed Bodies in Combination with Post-Mortem X-Ray Computed Tomography

Authors:

Soeren KOTTNER 1, Martin M. SCHULZ 2, Florian BERGER 1, Michael J. THALI 1, Dominic GASCHO 1

1 Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland;
2 Institute of Forensic Medicine, Ludwig-Maximilians-University Munich, Munich, Germany

Abstract:

Introduction
In the last few years, postmortem 3D body documentation, especially through the use of photogrammetry, has gained importance in the field of forensic medicine. For this purpose, conventional digital cameras are used to capture information within the visible part of the electromagnetic spectrum (i.e., visible light). Moreover, the use of multispectral photography allows the detection and documentation of traces and injuries, for instance, in the ultraviolet (UV) or near-infrared (NIR) range, which are otherwise invisible to the human eye. Although multispectral photography offers a wide range of applications for legal investigations, multispectral photogrammetry is not yet well known or widely used within the field of forensic medicine. Therefore, within this study and the framework of the VirtoScan project, a method for multispectral whole-body photogrammetry was developed and evaluated.

Materials and Methods
A multicamera setup based on four modified digital single-lens reflex cameras, different light sources, and additional lens filters was mounted on a mobile wooden frame. The setup was used in combination with a medical X-ray computed tomography (CT) scanner. Automatic table movement from the CT scanner was used to capture consecutive image sets of the body from head to toe. In addition to standard photogrammetry within the visible range, multispectral photogrammetry was performed under UV and NIR light sources at 365 nm, 400 nm, 860 nm and 960 nm on undressed human bodies and under blue light and NIR light sources at 450 nm and 860 nm on dressed mannequins. After the multispectral photogrammetry procedure was finished, a whole-body CT scan was conducted to capture the internal information of the human body.

Results
Multiview 3D reconstructions based on multispectral image data from four forensic cases and four different sets of dressed mannequins were carried out successfully. The overall quality and level of detail of the polygon models from the undressed bodies varied with regard to the spectral range of the image data. Dressed bodies captured under blue and visible light exhibited reduced quality and reduced level of detail on the polygon models within areas of dark-colored clothing. Whole-body photogrammetry for undressed bodies took approximately 5 min under UV illumination and approximately 3 min under visible light or NIR illumination. Whole-body photogrammetry for dressed bodies took approximately 12 min under blue-light illumination and approximately 4 min under visible light or NIR illumination.

Discussion and Conclusion
The multispectral camera setup allows the capture of whole body datasets in an extended spectral range within a few minutes. With the help of photogrammetry software, textured 3D models for different spectral ranges can be reconstructed. Multispectral 3D whole-body imaging in line with postmortem CT examinations allows the combination of multispectral information from external body documentation with radiological findings from internal body documentation. Multispectral 3D documentation extends the postmortem forensic documentation of the deceased, as it detects (and documents) latent evidence on the body and textiles and can assist in detecting subcutaneous injuries and bruises on the body.

Keywords:

Photogrammetry, Infrared and Ultraviolet Photography, Multicamera Setup, 3D Body Scanning, Forensic Imaging, Legal Medicine, VirtoScan

Details:

Full paper: 2124kottner.pdf
Proceedings: 3DBODY.TECH 2021, 19-20 Oct. 2021, Lugano, Switzerland
Paper id#: 24
DOI: 10.15221/21.24
Presentation video: 3DBodyTech2021_24_Kottner.mp4

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