Journal de recherche médico-légale

Three-Dimensional Crime Scene and Impression Reconstruction with Photogrammetry

Abstract

Brendan Chapman and Simon Colwill

It is commonplace for serious crime offences to be recorded in a three-Dimensional (3D) manner in order to facilitate retrospective analyses of spatial positions of exhibits and objects within a crime scene. The current and most common technique, for capturing these images is via 3D terrestrial laser scanners by forensic personnel. These units provide a highly accurate and detailed record of crime scenes but can be prohibitively expensive for many jurisdictions to adopt. Other scale recordings taken during crime scene examination, such as 3D shoe outsole impressions, require time-consuming digital photography capture or casting to be done.

Photogrammetry is a relatively new technique that is finding utility in a number of forensic capacities, mostly due to its ease of use and adoption of equipment already possessed by crime scene examiners, namely high-quality digital cameras. This research looked to evaluate the use of Agisoft^® Photoscan software for the 3D recording of small-scale crime scenes, along with the detailed capture of 3D outsole impressions. It was found that photogrammetry did have some utility in the recording of entire scenes, albeit potentially only as a tool for the courtroom and jurors. For 3D shoe outsole impressions created in sand, photogrammetry-derived 3D models resulted in -0.73 percent error. This shows promise, with further validation, as a potential replacement to current photographic capture techniques for these exhibits.