Application of Structured-Light 3-D Scanning to the Documentation of Plastic Fingerprint Impressions: A Quality Comparison with Traditional Photography

Plastic fingerprint impressions found at crime scenes are often too delicate for collection, leaving photography as the best option for documentation. However, traditional photography techniques can be inadequate in documenting minute 3-D details due to limitations of the camera and lighting conditions. This study investigated the feasibility of applying commercially available structured-light 3-D scanners in the documentation of plastic prints. Attempts were made to develop a procedure to extract curvature features from 3-D scanned fingerprints and flatten the friction ridge features into two-dimensional (2-D) images to allow direct comparison with the traditional photography in the CSIpix^® Matcher and NFIQ 2.0 software. Two 3-D scanners were evaluated a Dentsply Sirona inEos X5^® and an Artec Space Spider. In this study, 3-D scanners demonstrated robustness as well as efficiency in the collection of plastic fingerprint impressions in select substrates. One of the developed methods utilizing a discrete geometry operator and convexity features outperformed traditional photography, achieving higher software detection scores in minutiae count and match quality, while traditional photography could not always capture enough high-quality minutiae for comparisons, even after digital enhancement.