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Houston Forensic Science Center Ruger LCP LEA scans
datasetposted on 03.02.2020 by Susan Vanderplas, Heike Hofmann
Datasets usually provide raw data for analysis. This raw data often comes in spreadsheet form, but can be any collection of data, on which analysis can be performed.
Email firstname.lastname@example.org 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 three test kits (G1, G2, G3), each containing sets of known and unknown bullets. The kits are based on a set of ten consecutively rifled Luger LCP barrels, labeled A - J, with an additional three nonconsecutively rifled barrels (R1, R2, R3).
In each test kit, there are three test fires each from five consecutively rifled barrels, as well as ten questioned bullets whose source is unknown. This set is an open set, so the questioned bullets may have been fired from weapons not included in the test set, that is, from R1-R3 instead of A-J. Each bullet contains 6 land engraved areas, which are identified as Land 1-Land 6. In total, each test kit consists of 150 scans, for a total of 450 scans for all three test kits.
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. The total dataset size is 4.5 GB.
Generally, files are grouped as follows: SetGG/BarrelXX/BulletY/LandZ.x3p. Unknown bullets are stored in an Unknown folder within each set and are identified by U00, where 00 can be any two-digit number.
Information on x3p format: https://www.iso.org/standard/62310.html
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.