NBTRB (NIST Ballistic Toolmark Research Database)
Definition
NIST's repository of 3D surface topography data from bullets and cartridge cases fired from known firearms; used to develop and validate the CMC algorithm.
- Full name
- NIST Ballistic Toolmark Research Database
- Maintained by
- NIST, United States
- Contents
- 3D surface topography of bullets and cartridge cases
- Used for
- Developing and validating the CMC algorithm
Common questions
Why does a research database of known-source toolmarks matter for firearm identification science?+
It gives researchers ground-truth data, meaning the firing weapon for each sample is already known, so a matching algorithm such as CMC can be tested for how often it correctly matches same-source pairs and correctly excludes different-source pairs, which is how the method's error rate gets established.
Is NBTRB the same thing as a national ballistic image database used for casework searches?+
No. NBTRB is a research resource used to build and validate comparison algorithms, whereas an operational database used to search unknown crime-scene evidence against prior entries is a separate casework system with its own access rules and chain of custody.
Related terms
- ACS (Algorithmic Comparison Score)
- Extension of CMC that converts the raw cell-count score into a likelihood ratio using calibrated probability distributions from known match and non-match...
- Blind Verification
- The procedure in which a second fingerprint examiner independently performs the Analysis and Comparison stages without knowledge of the first examiner's conclusion....
- CMC (Congruent Matching Cells)
- NIST algorithm that divides two 3D surface topography maps into cell grids and counts cells meeting quantitative topographic-correlation, slope-agreement, and height-offset criteria;...
- Comparison Microscope
- Two compound microscope bodies connected by an optical bridge that presents one half of each body's image in a single split eyepiece...
- Confocal Microscopy
- An optical technique using a pinhole aperture to eliminate out-of-focus light; by scanning through focal planes, builds a 3D height map of...
- Evofinder
- A competing ballistic identification system by Evofinder Ltd. (UK) using a different optical acquisition method and algorithm to IBIS. Deployed in jurisdictions...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- NFI (Netherlands Forensic Institute)
- The Dutch national forensic laboratory, an early adopter of full likelihood-ratio reporting for pattern-comparison disciplines including firearm marks.
- Oblique Illumination
- Lighting applied at a very low angle to the document surface (below 10 degrees from horizontal) to reveal topographic features: writing indentations,...
- OSAC
- Organization of Scientific Area Committees for Forensic Science: established by NIST and DOJ in 2014, it develops consensus forensic standards through structured...
- SWGMAT
- Scientific Working Group for Materials Analysis, a US forensic science standards body (now succeeded by the OSAC Explosives Subcommittee). Published the Forensic...