Xiaoyu Alan Zheng, Johannes Soons, Robert Thompson

National Institute of Standards and Technology

alan.zheng@nist.gov

(301) 975-4095
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Disclaimer

Certain commercial equipment, instruments, or materials are 

identified in this presentation to specify the experimental 

procedure adequately. Such identification is not intended to 

imply recommendation or endorsement by the National Institute 

of Standards and Technology or the National Institute of Justice, 

nor is it intended to imply that the materials or equipment 

identified are necessarily the best available for the purpose.

www.nist.gov/forensics/ballisticsdb
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Criticism on Subjectivity

• Pattern evidence have come under scrutiny in recent years 

due to the subjective nature of the conclusions. 

• NAS 2009 “..the decision of the toolmark examiner remains 

a subjective decision based on unarticulated standards and 

no statistical foundation for estimation of error rates.” 

Solutions

Instrument suppliers, academia, and government laboratories 

are addressing these challenges through two approaches

• Improvement of the quality of ballistics imaging data. 

Namely through direct traceable measurements of the 

toolmark topography. 

• Development of objective mathematical criteria for the 

similarity of two samples with associated confidence limits 

and algorithms. 

www.nist.gov/forensics/ballisticsdb
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Statistical Framework

• In order to accurately model these distributions, large 

characteristic populations of diverse firearms are 

required. 

• It is not economically feasible for any one entity to 

generate the data required. It will require a collective 

effort. 

www.nist.gov/forensics/ballisticsdb
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Objective

• Open-access research database of bullet and cartridge 

case toolmark data consisting of reflectance microscopy 

images and three dimensional surface topography data.

Motivation:

• Foster development and validation of methods, 

metrics, and uncertainty estimates for objective 

ballistics identification.

• Improve scientific knowledge base on the similarity of 

marks from different firearms and the variability of 

marks from the same firearm. 

• Ease transition to application of 3D surface topography 

data.

www.nist.gov/forensics/ballisticsdb
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Crowdsourcing Data

To achieve a truly diverse and representative 

database, NIST cannot do this alone. It requires 

the help of the firearms forensic community
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Specimens and regions of interest

• Bullets (pristine): land engraving

• Cartridge cases: breech face and firing pin impressions

Areas “engraved” by barrel lands

Firing pin impression

Breech face impression

Ejector mark

Source: AFTE

www.nist.gov/forensics/ballisticsdb
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Studies and test fires of interest

• Consecutively manufactured firearm components.

• Same firearm firing many rounds of ammunition (persistence/decay).

• Same firearm firing different brands of ammunition (pre-existing marks).

• Firearms known to present identification challenges.

• Firearms representing the major class/subclass characteristics.

Parallel lines

Source: AFTE Source: AFTE

Random pattern of Concentric circles

peaks and valleys

www.nist.gov/forensics/ballisticsdb
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NIST measurements: reflectance microscopy

Forensic comparison Microscope

• Breech face impression (2X objective, 2.53 μm mean pixel size). 

• Firing pin impression (4X objective, 1.265 μm mean pixel size)

Ring light illumination 6 o’clock side light illumination

Ring light illumination Source: Leica

1944 pixels 

or 4.92 mm

1944 pixels 

or 2.46 mm

www.nist.gov/forensics/ballisticsdb
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NIST measurements: 3D surface topography

Disc scanning confocal microscope

• Bullet land engraving (20X objective, 1.563 μm mean pixel size). 

• Breech face impression

(10X objective, 3.125 μm mean pixel size)

• Firing pin impression

(20X objective, 1.563 μm mean pixel size)

www.nist.gov/forensics/ballisticsdb
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Data transfer (measurement data)

Measurement data is provided as raw data (no 

trimming, leveling, form removal, filtering etc.):

• Reflectance microscopy images in lossless TIFF format

• 3D topography data in X3P format (XML 3D surface 

Profile)

X - Position [m] Y - Position [m]

Reference Surface A

0 500 1000 1500 2000 2500 3000 3500

0

500

1000

1500

2000

2500

3000

3500

m

-57.18

-48.25

-25 

0 

25 

48.25 

56.44 

X - Position [m] Y - Position [m]

Filtered Surface A

500 1000 1500 2000 2500 3000 3500

500

1000

1500

2000

2500

3000

3500

m

-10.2

-4.97

-2.5 

0 

2.5 

4.97 

18.08

Database 

user

www.nist.gov/forensics/ballisticsdb
Standard File Exchange Format – X3P

• XML 3D Surface Profile (X3P) is an efficient, extensible, data format 

for storing surface topographies (ISO 25178-72).

• The format is being adopted for firearm and toolmark data by OSAC 

and OpenFMC (instrument manufacturers, academia, and 

government labs).

Each file contains 3 key records:

1) Header, data types, and axis definition

2) Meta data regarding the instrument and user

3) Profile data (x, y, z).

• The format is extensible. Extra, user-defined, data can be attached 

(e.g., firearm, ammunition, and measurement conditions).

• Open-source read/write functions, visualization software, and 

converters are available.

www.nist.gov/forensics/ballisticsdb
www.nist.gov/forensics/ballisticsdb
Results from Cross-Modality Study

• Cadre research successfully imported NIST confocal data into 

their correlation software and was able to correctly identify all 

test fires. 

• The same accuracy was achieved when comparing Cadre data 

vs NIST confocal data. 

• This test demonstrates that X3P is a suitable format for 

interoperability between different instruments.

• Additional tests have been conducted between NIST and Cadre 

Research, FBI, John Jay College, and the Nederland Forensic 

Institute. 

• All exchanged data files have been successfully opened and 

verified.

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www.nist.gov/forensics/ballisticsdb
OpenFMC Membership

• Anyone interested in being a part of the working group can join. 

Please contact: alan.zheng@nist.gov

• Current Members:

o NIST

o Cadre Research

o Alicona

o Nanofocus

o Leica

o Zeiss

o Forensic Technologies

o Sensofar

o Leeds

o NFI

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o John Jay College

o Oakland Police Department
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Cartridge Case:

• IdNumber

• Brand

• Cartridge designation

• Lot number

• Nominal caliber

• Primer surface

• Firing sequence

• Comments

Bullet:

• IdNumber

• Brand

• Cartridge designation

• Lot number

• Nominal caliber

• Weight

• Surface Material

• Firing sequence

• Comments

Cartridge case

Measurement:

• File name

• Creator

• Measurement type

• Measurand

• Has breech face?

• Has firing pin?

• Has ejector mark?

• Has aperture shear?

• Instrument brand

• Instrument model

• Lateral resolution

• Vertical resolution

• Lighting type

• Objective magnification

• Objective NA

• Comments

Bullet Measurement:

• File name

• Creator

• Measurement type

• Measurand

• Region of interest

• LEA or GEA number

• Instrument brand

• Instrument model

• Lateral resolution

• Vertical resolution

• Lighting type

• Objective magnification

• Objective NA

• Comments

Cartridge case

Measurement:

• File name

• Creator

• Measurement type

• Measurand

• Has breech face?

• Has firing pin?

• Has ejector mark?

• Has aperture shear?

• Instrument brand

• Instrument model

• Lateral resolution

• Vertical resolution

• Lighting type

• Objective magnification

• Objective NA

• Comments

Firearm:

• IdNumber

• Brand

• Model

• Caliber

• Firing pin class

• Breech face class

• Number of lands

• Twist direction

Study:

• Name

• Creator

• Description

• Literature reference

• Has consecutive?

• Has persistence?

• Has different ammo?

Cartridge case:

• IdNumber

• Brand

• Lot number

• Nominal caliber

• Primer surface

• Firing sequence

• Comment

Data transfer (meta data)

• Data is organized into toolmark studies

• Each study dataset has a spreadsheet with 

meta data.

Study:

• Name

• Creator

• Description

• Literature reference

• Has consecutive?

• Has persistence?

• Has different ammo?

Firearm:

• IdNumber

• Brand

• Model

• Caliber

• Firing pin class

• Breech face class

• Number of lands

• Twist direction

Bullet:

• IdNumber

• Brand

• Cartridge designation

• Lot number

• Nominal caliber

• Weight

• Surface Material

• Firing sequence

• Comments

Bullet Measurement:

• File name

• Creator

• Measurement type

• Measurand

• Region of interest

• LEA or GEA number

• Instrument brand

• Instrument model

• Lateral resolution

• Vertical resolution

• Lighting type

• Objective magnification

• Objective NA

• Comments

Cartridge Case:

• IdNumber

• Brand

• Cartridge designation

• Lot number

• Nominal caliber

• Primer surface

• Firing sequence

• Comments
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www.nist.gov/forensics/ballisticsdb
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www.nist.gov/forensics/ballisticsdb
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www.nist.gov/forensics/ballisticsdb
Applications of the Data

• Algorithm Development

• Statistical Analysis

• Training

• Virtual Microscopy

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http://www.cadreforensics.com/viewer.html
Upload Process and Quality Checks

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Registration for User 

Account

Perform meta data 

entry and file uploads

Uploaded Data Enters 

Quarantine 

Admin Reviews Meta 

Data and X3P 

Formatting

Data Released and 

Available for Public

Allow NIST to know who is 

performing the uploads.

Allow NIST to ensure the files 

uploaded are not malicious.

Allow NIST to check for junk data 

or incorrect implementation of 

the X3P format. Also to check 

meta data accuracy. 

www.nist.gov/forensics/ballisticsdb
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Future of the NBTRD

• NIST will continue to curate and manage the database

• NIST will continue to market, collect, measure, and 

enter in new sets of test fires for added diversity

• 2017 NIJ funding

• Administrative reporting functions

• Improve upload process efficiency

• Improve search results with advanced filtering and 

sorting functionality

• Ensure data accessibility and integrity

• Entrance of forensic laboratory reference collections

www.nist.gov/forensics/ballisticsdb
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Colt Glock Ruger

Smith & Wesson Sig Sauer

NIJ Research: Initial Population study

www.nist.gov/forensics/ballisticsdb
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www.nist.gov/forensics/ballisticsdb
Thanks for your attention!

Questions?

alan.zheng@nist.gov

johannes.soons@nist.gov

robert.m.thompson@nist.gov

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www.nist.gov/forensics/ballisticsdb