Elsevier

Forensic Science International

Volume 261, April 2016, Pages 123-128
Forensic Science International

Technical Note
Multi-camera system for 3D forensic documentation

https://doi.org/10.1016/j.forsciint.2016.02.003Get rights and content

Highlights

  • The botscan© and PhotoScan© produced 360° three-dimensional (3D) models.

  • The 3D models had very detailed geometries and textures depending on the settings.

  • This system represents a fast and markerless method of 3D documentation in the forensic field.

Abstract

Three-dimensional (3D) surface documentation is well established in forensic documentation. The most common systems include laser scanners and surface scanners with optical 3D cameras. An additional documentation tool is photogrammetry. This article introduces the botscan© (botspot GmbH, Berlin, Germany) multi-camera system for the forensic markerless photogrammetric whole body 3D surface documentation of living persons in standing posture.

We used the botscan© multi-camera system to document a person in 360°. The system has a modular design and works with 64 digital single-lens reflex (DSLR) cameras. The cameras were evenly distributed in a circular chamber. We generated 3D models from the photographs using the PhotoScan© (Agisoft LLC, St. Petersburg, Russia) software.

Our results revealed that the botscan© and PhotoScan© produced 360° 3D models with detailed textures. The 3D models had very accurate geometries and could be scaled to full size with the help of scale bars.

In conclusion, this multi-camera system provided a rapid and simple method for documenting the whole body of a person to generate 3D data with Photoscan©.

Introduction

Three-dimensional (3D) surface documentation is well established in the field of forensic documentation. Crime scenes and corpses are scanned using laser scanners or surface scanners with optical 3D cameras, and photogrammetry is an additional documentation tool [1], [2], [3], [4], [5], [6]. The 3D results provide investigators with important additional information in many cases [7], [8], [9], [10]. Some data are used for 3D comparisons between patterned injuries and the presumed injury-causing instruments.

Even in cases with living persons, including suspects and victims, 3D documentation using 3D scanning or photogrammetry is steadily increasing [11], [12]. One example application is the determination of the body stature of a suspected person for the police [12]. At our institute, we also use 3D photogrammetry to document patterned injuries during physical examinations following assaults.

Regardless of the system used, the main difficulty in documenting living persons is movement. Movement may result from respiration, bloodstream motion, shifts in position or balance control [13]. The larger the area to be documented, the greater the influence of movement on the accuracy of the documentation. In rare cases, suspects who are aware of these limitations attempt to interfere with surface scans by moving their facial muscles. Due to the above-mentioned difficulties of documenting living persons, an alternative documenting procedure is needed. This procedure should meet the following requirements: short documentation times (ms rather than s) making the measurements more robust in the presence of motion, the requirement of a low number of scans to capture the whole body, and an accuracy that is comparable to that of existing procedures.

In 2013, the company botspot (botspot GmbH, Berlin, Germany) introduced a 3D documentation system that utilizes synchronized digital multiple single-lens reflex (DSLR) cameras to document the whole body in one shot for the production of 3D prints [14].

This article introduces the botscan© multi-camera system for the forensic markerless photogrammetric whole body 3D surface documentation of living persons in standing posture.

Section snippets

Hardware

The 3D scanning system developed by the botspot company is called botscan©. The system has a modular design and consists of 12 panels forming a cylindrical chamber with a diameter of 3.35 m. One of the panels serves as an entry door. A total of 64 cameras are used, with 60 cameras distributed evenly – five placed vertically on each panel - and four cameras placed on top of the chamber (Fig. 1). This setup allows for 360° recording of any object placed in the center of the cylinder. The cameras

Discussion and conclusion

This technical note reports a system for rapidly generating 360° documentations of persons. The botscan© multi-camera system controlled by the DSLR Remote Pro Multi-Camera© software generates 64 images of a person. The images are processed into textured 3D models using the PhotoScan© software.

Currently used systems, such as laser scanners or surface scanners with optical 3D cameras, only cover parts of the body. To generate a 3D model of the whole body of a person, at least two scans are

Acknowledgements

The authors thank Seraina Meier for support during the system set-up and calibration.

References (20)

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