Iowa State University

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Hamby 44 Ruger P-85 LEA scans

posted on 2020-02-03, 17:17 authored by Susan VanderplasSusan Vanderplas, Heike Hofmann
Email to obtain the data.

The data consist of scans of bullet land engraved areas in x3p format. The study is structured so that there are 10 barrels (numbered 1-10) used to fire the bullets in the study, with two bullets known to be fired from each barrel (Bullet1, Bullet2). Each bullet contains 6 land engraved areas, which are identified as Land 1-Land 6.

In addition to the 20 bullets with known provenance, there are 15 "unknown" bullets which can be matched to the 10 barrels, for a total of 35 bullets. Each bullet has 6 land engraved areas, for a total of 210 scans.

The x3p format provides for the inclusion of relevant metadata within the x3p file, including the machine used to scan the bullets, the operator, and the resolution of the scan. Each file is around 20 MB, for a total dataset size of 2.6 GB.

Files are grouped as follows: BarrelXX/BulletY/LandZ.x3p, with Unknown bullets identified by a letter from A-Z instead of a number (1 or 2).

Hamby studies, which use the same 10 barrels and have the same structure, have been used to test firearms examiners across the country. They use Ruger P85 barrels with 9mm ammunition.

Information on x3p format:

We have produced two R packages meant to work with this data:
- x3ptools (on CRAN, with dev versions on github at heike/x3ptools). x3ptools contains utilities for reading, writing, annotating, rendering, and exporting x3p data to other formats.
- bulletxtrctr (dev version on github at heike/bulletxtrctr). bulletxtrctr contains utilities for extracting useful data from bullet LEA scans as well as a matching algorithm used to match unknown bullets to the barrels they were fired from.

Scans were created by the Roy J. Carver Microscopy Lab at Iowa State.


VPR Funds, 290-17-04-16-1000

National Institutes of Standards and Technology, 426-17-02


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