APPLICATION NOTE

SensoMATCH®
bullet comparison software‣ Introduction
To match a bullet to a firearm, a trained examiner traditionally uses a microscope to compare
the striations on each available ‘land area’ on the bullet to the land areas on a (known) bullet
fired from the firearm. Although it has been reliable, this process is tedious and subjective.

‣ Methodology
Sensofar is working to provide quantitative data on bullet lands using optical 3-dimensional
metrology. SensoMATCH® is a new program that fully automates IC and bullet comparison.
The process typically consists of five steps:

Land surface measurement

IC surface & mean profile

Pairs of IC surfaces are mathematically compared by extracting mean profiles from each surface and calculating a cross correlation function (CCFmax). Identical profiles have aCCFmax = 1.0. Lower correlations yield a lower CCFmax value, typically 0.2 - 0.4. Higher scores
thus indicate the confidence level of a match.

A single comparison of 2 bullets each with 6 lands
results in 36 CCFmax scores in a 6x6 matrix

SensoMATCH® bullet comparison with the Q six inspection system

This comparison task scales very rapidly – comparing 15
unknown bullets to 20 known bullets results in 10,800 scoresin 300 matrices.

‣ SensoMATCH® streamlines bullet comparison
To simplify analysis, we can calculate a single composite
score for each bullet pair – Sequence Average Maximum(SAM) – that provides a clear indication of a match betweenbullets. The user specifies the threshold value that is used toidentify matches (see graphic below right).
The entire John Hamby dataset of 15 vs. 20 bullets(10,800 comparisons) can be processed in approximately 4 seconds, resulting in a spreadsheet that identifies
the top matches for each unknown bullet.

‣ Additional features
SensoMATCH® has additional features that make it an ideal
tool for research in bullet comparisons based on 3D surface
metrology:
••

•
•

•

John Hamby test is correctly solved(SAM threshold 0.5)

Training mode.
SensoMAP template for IC comparison using
customized data processing and comparison
parameters.
Missing lands compatibility.
Comparing a set of known bullets to itself isuseful for calculating statistical values for‘Known Matches vs. Known Non-Matches’ andthen using this to define SAM thresholds (seegraphic right).
This approach to data analysis can be madeusing a variety of optical metrology systems,
including the Sensofar family of optical metrology systems.

Establishing SAM thresholdbased on the histogram of CFFmax values

Sensofar is a leading-edge technology company with the highest quality standards within the field of surface metrology.
HEADQUARTERS

SALES OFFICESALES OFFICESENSOFAR METROLOGY
Parc Audiovisual de Catalunya
Ctra. BV-1274, KM 108225 Terrassa, Spain

SENSOFAR ASIA
Room 102, Building C
No. 838, GUANGJI Road, HONGKOU District
200434 Shanghai, PR CHINASENSOFAR USA8655 E Via De Ventura
Suite G168
Scottsdale, AZ 85258 , USA

Tel. +34 93 700 14 92
Tel. +86 21 61400058
Fax +34 93 786 01 16
Fax +86 21 61400059
info@sensofar.com
info.asia@sensofar.com
www.sensofar.com
www.sensofar.com
SensoMATCH® bullet comparison with the Q six inspection system

Tel. +1 800 530-3097
Fax +1 419 745-1506
info@sensofarusa.com
www.sensofarusa.com