8
Experimental Evidence on Sources of Variability and Imaging Standards

The performance studies of the Integrated Ballistics Identification System (IBIS) platform—the current standard for ballistic imaging—summarized in Section 4–D provide context for the committee’s own analyses. The core of the experimental work performed by the committee was coordinated by the Office of Law Enforcement Standards of the National Institute of Standards and Technology (NIST), with whom the National Institute of Justice executed a separate contract to perform analyses at the committee’s direction.

Given the committee’s basic charge, an ideal test would involve the creation of a prototype national reference ballistic image database (RBID), exceeding the size of the De Kinder et al. (2004) exhibit set, and thus getting a direct impression of automated systems’ ability to detect sameness amidst a vast array of exhibits with highly similar class characteristics. However, such a massive collection was clearly beyond the scope of our available resources. Working with NIST, and recognizing the work in previous studies, we judged it best to focus our analyses on narrower objectives. Our experimentation was aimed at generating an exhibit set that—although small in size—could facilitate studies of system performance when both firearm and ammunition type are varied. Significantly, a main objective of our work was to study the effectiveness of one possible enhancement to the current National Integrated Ballistic Information Network (NIBIN) or, alternately, a possible design choice for a new national RBID: a switch from two-dimensional photography to three-dimensional surface measurement as an imaging standard. When NIST and the committee began its work, three-dimensional profilometry analyses had been performed on bullets but had not yet been attempted on cartridge case markings; our experimental work



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