3D documentation and visualization of external injury findings by integration of simple photography in CT/MRI data sets (IprojeCT)

Cost-effective 3D documentation device in forensic medicine

3D documentation in forensics and forensic medicine is being introduced more frequently in various institutes around the world. However, several institutes lack capacity in finances as well as staff to perform 3D documentations regularly. This technical paper aims to present a 3D documentation device that is low cost and easy to use and is a viable entry level solution for forensic medical departments. For this the small single-board computer Raspberry Pi 4 was used in conjunction with its high quality (HQ) camera module to create the 3DLamp - a flexible, low cost and easy to use documentation device. Besides a detailed description of the device this paper also presents four case examples where a 3D documentation was performed and analyses the acquired data and the created 3D models. It was found that the device returns feasible 3D models that appear usable for forensic 3D reconstructions.

Augmented reality in forensics and forensic medicine - Current status and future prospects

Forensic investigations require a vast variety of knowledge and expertise of each specialist involved. With the increase in digitization and advanced technical possibilities, the traditional use of a computer with a screen for visualization and a mouse and keyboard for interactions has limitations, especially when visualizing the content in relation to the real world. Augmented reality (AR) can be used in such instances to support investigators in various tasks at the scene as well as later in the investigation process. In this article, we present current applications of AR in forensics and forensic medicine, the technological basics of AR, and the advantages that AR brings for forensic investigations. Furthermore, we will have a brief look at other fields of application and at future developments of AR in forensics.

Beyond the visible spectrum - applying 3D multispectral full-body imaging to the VirtoScan system

Multispectral photography offers a wide range of applications for forensic investigations. It is commonly used to detect latent evidence and to enhance the visibility of findings. Additionally, three-dimensional (3D) full-body documentation has become much easier and more affordable in recent years. However, the benefits of performing 3D imaging beyond the visible (VIS) spectrum are not well known, and the technique has not been widely used in forensic medical investigations. A multicamera setup was used to employ multispectral photogrammetry between 365 and 960 nm in postmortem investigations. The multicamera setup included four modified digital cameras, ultraviolet (UV) and near-infrared (NIR) light sources and supplemental lens filters. Full-body documentation was performed in conjunction with the use of a medical X-ray computed tomography (CT) scanner to automate the imaging procedure. Textured 3D models based on multispectral datasets from four example cases were reconstructed successfully. The level of detail and overall quality of the 3D reconstructions varied depending on the spectral range of the image data. Generally, the NIR datasets showed enhanced visibility of vein patterns and specific injuries, whereas the UV-induced datasets highlighted foreign substances on the skin. Three-dimensional multispectral full-body imaging enables the detection of latent evidence that is invisible to the naked eye and allows visualization, documentation and analysis of evidence beyond the VIS spectrum.

VirtoScan-on-Rails - an automated 3D imaging system for fast post-mortem whole-body surface documentation at autopsy tables

Two-dimensional photographic documentation is a substantial part of post-mortem examinations for legal investigations. Additional three-dimensional surface documentation has been shown to assist in the visualization of findings and contribute to the reconstruction of the sequence of events. However, 2D photo documentation and, especially, 3D surface documentation, are time-consuming procedures that require specially trained personnel. In this study a 3D imaging system, called VirtoScan-on-Rails, was developed to automate and facilitate 3D surface documentation for photo documentation in autopsy suites. The imaging system was built to quickly acquire photogrammetric image sets of whole bodies during different stages of external and internal examinations. VirtoScan-on-Rails was set up in the autopsy suite of the Zurich Institute of Forensic Medicine at the University of Zurich (Zurich, Switzerland). The imaging system is based on a movable frame that carries a multi-camera array. Data quality and the applicability of the system were analyzed and evaluated within two test series. Up to 200 overlapping photographic images were acquired at consecutive image-capturing positions over a distance of approximately 2000 mm. The image-capturing process took 1 min and 23 s to acquire a set of 200 images for one side of the body. During test series one and two, 53 photogrammetric image sets taken from 31 forensic cases were successfully reconstructed. VirtoScan-on-Rails is an automated, fast and easy-to-use 3D imaging setup for autopsy suits. It facilitates documenting bodies during different stages of forensic examinations and allows standardizing the procedure of photo documentation.

Forensic 3D documentation of skin injuries using photogrammetry: photographs vs video and manual vs automatic measurements

Accurate and precise documentation of lesions is an important aspect of the forensic pathologists' work. Photogrammetry provides a useful tool to take precise measurements from photographs. These photographs are normally acquired with single camera photographs, but the procedure is quite time-consuming. Video recording has the potential to record a larger amount of image data faster. We documented 33 cadaveric skin lesions, using photographs and video recordings. The dimensions of the lesions ranged between 0.27 and 21.8 cm. The measurements of the lesions were extracted with both manual and automatic point measurements from photographs and from video frames, respectively. Very small differences (mean and median < 1 mm) were found between measurements taken in photographs versus video frames. Video frames were often blurred, preventing clear demarcation of the edges of the lesions and presenting a larger amount of noise in the 3D models. The differences between the manual point and automatic point measurements were very small (mean and median < 1 mm), but the manual procedure is to be preferred, since automatic points were not always located on the edges of the lesions. The only aspect in which video frames were superior to photographs was the recording time: video recording was almost five times faster than the photo sessions. In conclusion, this study shows that precise and comparable measurements can be extracted both from photographs and video frames. The video is the fastest method, but the use of photographs is still recommended. Manual measurements are more precise than automatic measurements and equally time-consuming.

Validation and evaluation of measuring methods for the 3D documentation of external injuries in the field of forensic medicine

Three-dimensional (3D) measurement techniques are gaining importance in many areas. The latest developments brought more cost-effective, user-friendly, and faster technologies onto the market. Which 3D techniques are suitable in the field of forensic medicine and what are their advantages and disadvantages? This wide-ranging study evaluated and validated various 3D measurement techniques for the forensic requirements. High-tech methods as well as low-budget systems have been tested and compared in terms of accuracy, ease of use, expenditure of time, mobility, cost, necessary knowhow, and their limitations. Within this study, various commercial measuring systems of the different techniques were tested. Based on the first results, one measuring system was selected for each technique, which appeared to be the most suitable for the forensic application or is already established in forensic medicine. A body of a deceased, a face and an injury of a living person, and a shoe sole were recorded by 11 people with different professions and previous knowledge using the selected systems. The results were assessed and the personal experiences were evaluated using a questionnaire. In addition, precision investigations were carried out using test objects. The study shows that the hand-held scanner and photogrammetry are very suitable for the 3D documentation of forensic medical findings. Their moderate acquisition costs and easy operation could lead to more frequent application in forensic medicine in the future. For special applications, the stripe-light scanner still has its justification due to its high precision, the flexible application area, and the high reliability. The results show that, thanks to the technological advances, the 3D measurement technology will have more and more impact on the routine of the forensic medical examination.

CT-scan vs. 3D surface scanning of a skull: first considerations regarding reproducibility issues

Three-dimensional surface scanning (3DSS) and multi-detector computed tomography (MDCT) are two techniques that are used in legal medicine for digitalizing objects, a body or body parts such as bones. While these techniques are more and more commonly employed, surprisingly little information is known about the quality rendering of digitalized three-dimensional (3D) models provided by each of them. This paper presents findings related to the measurement precision of 3D models obtained through observation of a study case, where a fractured skull reconstructed by an anthropologist was digitalized using both post-mortem imaging methods. Computed tomography (CT) scans were performed using an 8-row MDCT unit with two different slice thicknesses. The variability of 3D CT models superimposition allowed to assess the reproducibility and robustness of this digitalization technique. Furthermore, two 3D surface scans were done using a professional high resolution 3D digitizer. The comparison of 3D CT-scans with 3D surface scans by superimposition demonstrated several regions with significant differences in topology (average difference between +1.45 and -1.22 mm). When comparing the reproducibility between these two digitalizing techniques, it appeared that MDCT 3D models led in general to greater variability for measurement precision between scanned surfaces. Also, the reproducibility was better achieved with the 3D surface digitizer, showing 3D models with fewer and less pronounced differences (from +0.32 to -0.31 mm). These experiments suggest that MDCT provides less reproducible body models than 3D surface scanning. But further studies must be undertaken in order to corroborate this first impression, and possibly explain the reason for these findings.