A comparative study of photogrammetric methods using panoramic photography in a forensic context

Abstract

Highlights Photogrammetry software provides an alternative method for documenting crime scenes  Photogrammetric measuring from images compared for accuracy with tape measuring  Distance endpoint identification improves accuracy of software measurements  Software removes transcription errors encountered with manual methods  Accurate data capture reliant on using complimentary measurement techniques AbstractTaking measurements of a scene is an integral aspect of the crime scene documentation process, and accepted limits of accuracy for taking measurements at a crime scene vary throughout the world. In the UK, there is no published accepted limit of accuracy, whereas the United States has an accepted limit of accuracy of 0.25 inch. As part of the International organisation for Standardisation 17020 accreditation competency testing is required for all work conducted at the crime scene. As part of this, all measuring devices need to be calibrated within known tolerances in order to meet the required standard, and measurements will be required to have a clearly defined limit of accuracy. This investigation sought to compare measurement capabilities of two different methods for measuring crime scenes; using a tape measure, and a 360 o camera with complimentary photogrammetry software application. Participants measured ten fixed and non-fixed items using both methods and these were compared to control measurements taken using a laser distance measure. Statistical analysis using a Wilcoxon Signed Rank test demonstrated statistically significant differences between the tape, software and control measurements. The majority of the differences were negligible, amounting to millimetre differences. The tape measure was found to be more accurate than the software application, which offered greater precision. Measurement errors were attributed to human error in understanding the operation of the software, suggesting that training be given before using the software to take measurements. Transcription errors were present with the tape measure approach. Measurements taken using the photogrammetry software were more reproducible than the tape measure approach, and offered flexibility with regards to the time and location of the documentation process, unlike manual tape measuring.

The Application of Photogrammetry in the Autopsy Room: A Basic, Practical Workflow*

“…Due to its accuracy in elaborating detailed 3D models of human bodies, photogrammetry may become an essential tool in forensic pathology. This technique is simple, cost-effective, and its acceptance in the scientific community is increasing (2)(3)(4)(5)(6).…”

Imaging in forensic science: Five years on

“…Empirical research has investigated the accuracy of 3D scene recording, for example a comparison of measurement data from two different methods for documenting crime scenes (a tape measure and a 360 camera with photogrammetry), found the manual method to be more accurate but the software application method more precise (Sheppard et al 2017). Additionally, drone-based aerial photography was found to produce high-quality images and therefore accurate large-scale 3D models of mock forensic scenes (Urbanova et al 2017a).…”

Virtual reality – level of immersion within the crime investigation

“…However, with the advent of equipment that is faster and easier to use, and the recent advances in software, police forces can now regularly capture and more importantly utilize 3D data for crime scene documentation [1]. Empirical research has investigated the accuracy of 3D scene recording, for example, a comparison of measurement data from two different methods for documenting crime scenes (a tape measure and a 360 camera with photogrammetry), found the manual method to be more accurate but the software application method more precise [2]. Further, 3D scan data may be combined with CCTV or eyewitness photographs, which can for example aid with identifying the spatial position of an individual or for profiling individuals (e.g.…”