Using virtual reality for forensic examinations of injuries.

The ability to accurately determine injury dimensions is an essential property of forensic documentation. The current standard for injury documentation is photography using a scale to approximate the injury dimensions in the image. The technical qualities of the photograph, such as orthogonality, depth of the field and sharpness of the desired area, are vital to obtaining a correct measurement. Adequate training of the forensic staff can reduce technical errors; nonetheless, there will always be some loss of information when visualizing an injury as a three-dimensional (3D) object on a two-dimensional (2D) photograph. The shortcomings of 2D photographs can be resolved by using 3D photogrammetry, which allows 3D documentation of persons and their injuries. A series of photographs has to be acquired and processed in photogrammetric software to create a photorealistic 3D model. In a prior study, a mannequin equipped with wound tattoos of known dimensions was documented with 3D photogrammetry using a multi-camera device. On the created 3D model, the dimensions of the injuries were then measured and compared to the dimensions approximated from standard forensic photographs. The results showed that the photogrammetric measurements in 3D are more accurate than the approximations performed with standard forensic photographs. In this subsequent study, the created 3D model was visualized and surveyed in virtual reality (VR), and the results were compared to the previous study. Our goal was to establish how accurately injuries can be measured in VR compared to the standard forensic photo documentation and photogrammetric method that is used on computer screens. We found that the measurements in VR are more accurate than the approximations from forensic photo documentation, but slightly less accurate than the photogrammetric measurements performed on a computer screen in dedicated software. In conclusion, photogrammetric software and virtual reality tools can both be used to make accurate size measurements of forensics-relevant injuries. Furthermore, 3D models can be visualized in varying ways allowing a much better understanding and review of injuries, even after the injury has healed.