Anna Wilson, Sophie Richards
Close range photogrammetry and optical surface scanning are two three-dimensional surface technologies that have recently developed into methods that are less expensive, more adaptable, and more accurate. However, the daily practice of forensic postmortem investigation has not yet fully tapped into their potential. In the current study, we compared the performance of stereophotogrammetry-based Vectra H11, a portable handheld surface scanner, and digital camera-based photogrammetry integrated with commercial Agisoft PhotoScan1 software. Three human subjects were chosen for the study: a 25-year-old woman who was still alive, two 63-year-old male forensic cases who had been admitted for postmortem examination at the Department of Forensic Medicine in Hradec Králové, Czech Republic, one of whom had died from traumatic, self-inflicted injuries (suicide by hanging), and the other of whom had been diagnosed with heart failure. With a Nikon 7000 digital camera and a handheld scanner, all three cases were concurrently documented in 3608 style and shot. Both procedures were used at different stages of the autopsy in addition to being used to record the pre-autopsy phase of the forensic cases. To create point clouds and 3D meshes, additional processing was applied to the sets of digital photos that were gathered (around 100 in each case). The number of points and polygons in the final 3D models (one pair for each person) were counted. They were then evaluated visually and statistically using the ICP alignment algorithm and a cloud point comparison technique based on closest point-to-point distances.