Forensic 3D documentation of bodies: Simple and fast procedure for combining CT scanning with external photogrammetry data

Forensic Reconstruction of a Fatal Stair-Related Fall Using Postmortem CT, Photogrammetry, and Virtual Reality: A Case Report

Three-dimensional (3D) documentation is increasingly being utilized in forensic investigations to record injuries and reconstruct crime scenes accurately. Although photogrammetry offers a low-cost and accessible method for capturing surface details, its integration with postmortem CT (PMCT) data and virtual reality (VR) can further enhance spatial understanding. We report a fatal case of a stair-related fall of a man in his 70s, in which we visualized the injuries by combining PMCT data with surface models of the body and the staircase. A 3D model of the bones was created from the PMCT data, whereas surface models of the body and staircase were generated using photogrammetry. The reconstructed scene was visualized in VR using a MetaQuest 3 headset. The reconstructed scene clearly demonstrated the spatial relationship between the stair edges and injury sites, such as the occipital region, midthoracic spine, and sacrum. The vertical distances between the injuries closely matched the staircase step depth, supporting the interpretation of stair-related falls. This method provides an intuitive and immersive understanding of injury mechanisms. Our approach demonstrates the feasibility and utility of integrating CT, photogrammetry, and VR in forensic death investigations, offering enhanced documentation and visualization that can benefit not only forensic experts but also legal professionals and juries.

FATAL: A Forensic AuTopsy Annotation tooL for digital recording of autopsy findings

The findings from forensic autopsies, where cause of death must be established and reported to legal authorities, are reported in paper-based formats. Practitioners are required to map 3D injury findings to 2D space. Here, we design and describe a digital Forensic AuTopsy Annotation tooL (FATAL), that can be used by practitioners to record systematically detailed autopsy findings onto an interactive 3D body model. We employ a user-centred design process involving an expert forensic medicine team. We describe the iteration process and the final functionality determined, based on in-depth analyses of forensic clinical workflows, and feedback on the types of complex cases confronting practitioners. FATAL functions include freehand drawing, a layer system for injury categorisation, trajectory plotting, surface area markings, and point-of-interest marking. Relevant external images, such as investigative report or autopsy photographs, can be loaded into the FATAL tool and assigned to individual annotations. The application streamlines workflows, supports template-driven documentation, and collates all forensic data into a single interface. Findings from the digital tool can be exported to a 2D report (PDF). We highlight the advancements in accuracy, efficiency, and reproducibility afforded by a digital tool for forensic autopsy documentation. Potential applications in forensic medical examinations beyond autopsies are described, along with specific areas for extension, such as supporting touch screen and pen inputs, export for 3D printing models and extending the tool's compatibility with custom 3D body models.

A consistent methodology for forensic photogrammetry scanning of human remains using a single handheld DSLR camera

Due to increasingly capable algorithms and more available processing power, photogrammetry is becoming a simple, cheap, and accurate alternative to 3D optical surface scanning. With adequate application, it can be a swift documentation technique for reconstructing the geometry and body surface of deceased persons in autopsies or other forensic medical examinations. Sufficiently easy and swift 3D documentation techniques may allow 3D imaging technologies to become part of the daily routine of any forensic medical examiner or other medical personnel. This paper presents a consistent and systematic photographing methodology (as an alternative to automated or intuitive methods) for photogrammetry scanning of human remains. Although it requires manual photography, the methods presented in this paper offer a swift and easy way to capture an accurate 3D model of human remains under almost any conditions. Four different photographing procedures were tested on four subjects: (i) a systematic circular technique with 100 photos, (ii) a systematic circular technique with 50 photos, (iii) a technique loosely mimicking cameras mounted on a postmortem CT device with 98 photos, and (iv) a technique mimicking cameras mounted on a postmortem CT device with 49 photos. Measurement accuracy was tested with the aid of six adhesive control points placed at approximately the same locations on each subject. Five different distances defined by these control points were measured and compared to the measurements taken by hand. 3D photogrammetry meshes created using these techniques were also compared with point clouds acquired using a 3D laser scanner. We found that a carefully composed, tested, and systematic photographing procedure significantly improved the quality of the photogrammetry models. In terms of relative difference compared to the hand measurements, both Techniques 1 and 2 produced close results, with an average relative difference of 0.160% and 0.197% and a maximum relative difference of 0.481% and 0.481%, respectively, while models reconstructed from images taken using Techniques 3 and 4 seemed to be much less accurate, with an average relative difference of 0.398% and 0.391% and a maximum relative difference as high as 1.233% and 1.139%, respectively. This study highlights the importance of a scientifically tested methodology for obtaining high-quality 3D models in forensic applications.

Key points

Close-range photogrammetry is an easy, fast, and cheap way to acquire 3D models of human remains of forensic importance.A carefully composed, tested, and systematic photographing procedure has a key role and can greatly increase the quality of photogrammetry models.A photogrammetry-based 3D-digitalization technique could be developed and adopted as part of the daily routine during autopsies.Photogrammetry-based 3D models are much quicker to acquire, look more photorealistic, and are almost as accurate as certain laser scanner-based models.

Foundations and guidelines for high-quality three-dimensional models using photogrammetry: A technical note on the future of neuroanatomy education

Hands-on dissections using cadaveric tissues for neuroanatomical education are not easily available in many educational institutions due to financial, safety, and ethical factors. Supplementary pedagogical tools, for instance, 3D models of anatomical specimens acquired with photogrammetry are an efficient alternative to democratize the 3D anatomical data. The aim of this study was to describe a technical guideline for acquiring realistic 3D anatomic models with photogrammetry and to improve the teaching and learning process in neuroanatomy. Seven specimens with different sizes, cadaveric tissues, and textures were used to demonstrate the step-by-step instructions for specimen preparation, photogrammetry setup, post-processing, and display of the 3D model. The photogrammetry scanning consists of three cameras arranged vertically facing the specimen to be scanned. In order to optimize the scanning process and the acquisition of optimal images, high-quality 3D models require complex and challenging adjustments in the positioning of the specimens within the scanner, as well as adjustments of the turntable, custom specimen holders, cameras, lighting, computer hardware, and its software. MeshLab® software was used for editing the 3D model before exporting it to MedReality® (Thyng, Chicago, IL) and SketchFab® (Epic, Cary, NC) platforms. Both allow manipulation of the models using various angles and magnifications and are easily accessed using mobile, immersive, and personal computer devices free of charge for viewers. Photogrammetry scans offer a 360° view of the 3D models ubiquitously accessible on any device independent of operating system and should be considered as a tool to optimize and democratize the teaching of neuroanatomy.

A Virtual, 3D Multimodal Approach to Victim and Crime Scene Reconstruction

In the last two decades, forensic pathology and crime scene investigations have seen a rapid increase in examination tools due to the implementation of several imaging techniques, e.g., CT and MR scanning, surface scanning and photogrammetry. These tools encompass relatively simple visualization tools to powerful instruments for performing virtual 3D crime scene reconstructions. A multi-modality and multiscale approach to a crime scene, where 3D models of victims and the crime scene are combined, offers several advantages. A permanent documentation of all evidence in a single 3D environment can be used during the investigation phases (e.g., for testing hypotheses) or during the court procedures (e.g., to visualize the scene and the victim in a more intuitive manner). Advanced computational approaches to understand what might have happened during a crime can also be applied by, e.g., performing a virtual animation of the victim in the actual context, which can provide important information about possible dynamics during the event. Here, we present an overview of the different techniques and modalities used in forensic pathology in conjunction with crime scene investigations. Based on our experiences, the advantages and challenges of an image-based multi-modality approach will be discussed, including how their use may introduce new visualization modalities in court, e.g., virtual reality (VR) and 3D printing. Finally, considerations about future directions in research will be mentioned.

Mechatronic Design and Experimental Research of an Automated Photogrammetry-Based Human Body Scanner

The article concerns the mechatronic design and experimental investigations of the HUBO automated human body scanning system. Functional problems that should be solved by using the developed scanning system are defined. These include reducing the number of sensors used while eliminating the need to rotate a human and ensuring the automation of the scanning process. Research problems that should be the subject of experimental research are defined. The current state of the art in the field of systems and techniques for scanning the human figure is described. The functional and technical assumptions for the HUBO scanning system are formulated. The mechanical design of the scanner, the hardware and information system architectures as well as the user's mobile application are presented. The method of operation of the scanning system and its innovative features are discussed. It is demonstrated that the developed solution of the scanning system allows the identified problems to be overcome. The methodology of the experimental research of the scanning system based on the photogrammetry technique is described. The results of laboratory studies with the use of dummies and experimental research with human participation are presented. The scope of the research carried out allows answers to the identified research problems related to the scanning of the human figure using the photogrammetry technique to be obtained. As part of laboratory tests using a measuring dummy, a mean error of 0.65 mm and standard deviation of the mean of 0.65 mm were obtained for the best scanner configuration. Research with human participation was carried out for the scanner version, in which the scanning time was 30 s, with the possibility of its reduction to 15 s. The results of studies using realistic dummies and with human participation were compared using the root mean square error parameter (RMSE) provided by the AliceVision framework, which was available for all analyzed objects. As a result, it was observed that these results are comparable, i.e., the RMSE parameter is equal to about 1 px.

Analysis of the Influence of the Geometrical Parameters of the Body Scanner on the Accuracy of Reconstruction of the Human Figure Using the Photogrammetry Technique

This article concerns the research of the HUBO full-body scanner, which includes the analysis and selection of the scanner's geometrical parameters in order to obtain the highest possible accuracy of the reconstruction of a human figure. In the scanner version analyzed in this paper, smartphone cameras are used as sensors. In order to process the collected photos into a 3D model, the photogrammetry technique is applied. As part of the work, dependencies between the geometrical parameters of the scanner are derived, which allows to significantly reduce the number of degrees of freedom in the selection of its geometrical parameters. Based on these dependencies, a numerical analysis is carried out, as a result of which the initial values of the geometrical parameters are pre-selected and distribution of scanner cameras is visualized. As part of the experimental research, the influence of selected scanner parameters on the scanning accuracy is analyzed. For the experimental research, a specially prepared dummy was used instead of the participation of a real human, which allowed to ensure the constancy of the scanned object. The accuracy of the object reconstruction was assessed in relation to the reference 3D model obtained with a scanner of superior measurement uncertainty. On the basis of the conducted research, a method for the selection of the scanner's geometrical parameters was finally verified, leading to the arrangement of cameras around a human, which guarantees high accuracy of the reconstruction. Additionally, to quantify the results, the quality rates were used, taking into account not only the obtained measurement uncertainty of the scanner, but also the processing time and the resulting efficiency.

A multi-method assessment of 3D printed micromorphological osteological features

The evaluation of 3D printed osteological materials has highlighted the difficulties associated with accurately representing fine surface details on printed bones. Moreover, there is an increasing need for reconstructions to be demonstrably accurate and reliable for use in the criminal justice system. The aim of this study was to assess the surface quality of 3D prints (n = 9) that presented with micromorphological alterations from trauma, taphonomy and pathology processes. The archaeological bones were imaged using micro-CT scanning and 3D printed with selective laser sintering (SLS) printing. A multi-method experimental approach subsequently identified: (1) the 3D printed bones to be metrically accurate to within 1.0 mm; (2) good representation of micromorphological surface features overall, albeit with some loss of intricate details, depths, and fine textures that can be important for visual processing; (3) five of the nine 3D printed bones were quantitatively scored as accurate using the visual comparison method; and, (4) low mesh comparison distances (± 0.2 mm) between the original models and the digitised 3D print models. The findings offer empirical data that can be used to underpin 3D printed reconstructions of exhibits for use in courts of law. In addition, an adaptable pathway was presented that can be used to assess 3D print accuracy in future reconstructions.

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.

Overview of the use of 3D printing in forensic medicine

In forensic medicine the use of so-called 3D printing is a niche application, whereas developments elsewhere in this field are rapidly advancing worldwide. The most common and widespread technology is fusion deposit modelling with polylactic acids (PLA). Although the equipment and materials may be relatively inexpensive and 3D printing relatively fast, the resulting end products tend to also have negative properties, such as poor durability and mechanical anisotropy, which may be an issue depending on the application. In forensic medicine, applications in the field of weapons technology and biomechanical models are realistic and 3D printing is already being used for demonstrations at court hearings and in teaching and also as a technique for building spare parts or accessories. Having a low-cost option for rapid prototyping on-site is particularly useful for the development phase. For finished 3D designs more expensive manufacturing options with a choice of materials with significantly broader mechanical or thermal properties are available. As the technology is undergoing major changes, one should carefully consider whether to enter the field oneself, buy own hardware, use a 3D printing service or seek cooperation possibly with a nearby partner.

Postmortem Computed Tomography in Firearm Homicides: A Retrospective Case Series

Postmortem computed tomography (PMCT) is integrated into the evaluation of decedents in several American medical examiner offices and medicolegal death investigative centers in many other countries. We retrospectively investigated the value of PMCT in a series of firearm homicide cases from a statewide centralized medical examiner’s office that occurred during 2016. Autopsies were performed or supervised by board‐certified forensic pathologists who reviewed the PMCT scans prior to autopsy. PMCT scans were re‐evaluated by a forensic radiologist blinded to the autopsy findings and scored by body region (head–neck, thoracoabdominal, and extremities). Injury discrepancies were scored using a modified Goldman classification and analyzed with McNemar’s test. We included 60 males and 20 females (median age 31 years, range 3–73). Based on PMCT, 56 (79.1%) cases had injuries relevant to the cause of death in a single body region (24 head–neck region, 32 thoracoabdominal region). Out of these 56 cases, 9 had a missed major diagnosis by PMCT outside that region, including 6 extremity injuries visible during standard external examination. Yet all had evident lethal firearm injury. We showed that PMCT identifies major firearm injuries in homicide victims and excludes injuries related to the cause of death in other regions when a single body region is injured. Although PMCT has a known limited sensitivity for soft tissue and vascular pathology, it can be combined with external examination to potentially reduce or focus dissections in some of these cases depending on the circumstances and medicolegal needs.

Virtual reality and integrated crime scene scanning for immersive and heterogeneous crime scene reconstruction

Crime scene reconstruction plays a significant role in crime solving by helping to determine the course of events. Non-invasive, high-resolution measurement and increased insight are always the goal of forensic crime scene documentation. However, entire crime scenes cannot be effectively reconstructed with traditional methods. In this study, we present a portable system that consists of a laser scanner, two hand-held structured light scanners and a low-cost virtual reality (VR) headset with a mobile power supply to conduct multi-angle and omnidirectional three-dimensional spatial data collection of crime scenes. To demonstrate practical use, a real case has been analysed to verify the feasibility and effectiveness of the system. The system accurately obtains information on decedent injuries, possible injury-inflicting tools and on-site traces. Various types of evidence from the crime scene can be jointly studied by three-dimensional visualization to develop a cohesive story. The data are presented via immersive VR rather than displayed on computer screens. The relationship between evidence chains enables us to achieve a complete crime scene reconstruction, using the specialized knowledge of experts and computer-aided forensic tools to analyse the causes of damage and identify suspects. The use of three- dimensional imaging techniques allows a more insightful survey and several useful analyses, such as accurate measurement, relative blood source location determination and injury-inflicting tool comparison.

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.