The invented NIST Ballistics Identification System (NBIS) using three-dimensional (3D) topography measurements on correlation cells can promote high accuracy and fast ballistics identifications . The use of paired correlation cells can identify the valid correlations area and eliminate the invalid correlation area from identification. The proposed synchronous processing can correlate dozens even hundreds cell pairs at the same time. Based on the correlation cells, a Contiguous Matching Cells (CMC) criterion is proposed for 2D and 3D ballistics and toolmark identifications. A CMC + Distribution Pattern method using three searching vectors (cross correlation function maximum CCFmax, spatial distribution pattern in x-y, and registration angle θ of the paired correlation cells) is also proposed for the National Ballistics Evidence Search Engine (NBESE) for high accuracy and fast ballistics evidence search. The proposed NBIS and NBESE can cover all case scenarios of bullets, cartridge cases and toolmarks, including cartridge cases with complex-shaped firing pin signatures and damaged bullets. All the parameters and algorithms in this invention will be in the public domain and subject to open tests. A measurement uncertainty and error rate reporting procedure will be developed that can greatly add to the scientific support to the ballistics identification specialty, and give confidence to the trier of fact in court proceedings. Both the NBIS and NBESE will be engineered to employ publicly available software and database file protocols, and provide published search algorithms and statistical models. In this way interoperability between different ballistics identification systems using this invention can be achieved. That will make the NBIS and NBESE suitable for ballistics identifications and evidence searches with large national databases.
Citation: Journal of Association of Firearm and Tool-mark Examiners
Pub Type: Journals
Forensic science, ballistics identification, topography measurements, correlation cells, Contiguous Matching Cells, CMC.