IBIS, NIBIN and BDAS — Forensic Ballistics

IBIS, NIBIN and BDAS — Modern Approaches to Ballistics Identification

Forensic Ballistics Primer — concise overview and technical comparison

Introduction

Forensic ballistics is the branch of forensic science concerned with the identification, individualization, evaluation and analysis of firearm evidence such as firearms, cartridge cases, bullets, gunshot residue (GSR), firing-pin marks and striation marks. When a projectile is fired from a firearm, contact between the projectile and the firearm's surfaces leaves distinctive microscopic marks. Barrel rifling produces characteristic striations on bullets; firing pins and extractor/ejector mechanisms leave marks on cartridge cases. These unique, random microscopic irregularities are often described as a firearm's ballistic fingerprint and can be used to identify — or exclude — a particular weapon as the source of recovered evidence.

When bullets or cartridge cases are recovered at a crime scene, a forensic ballistics expert will typically test-fire a suspect's firearm and compare test-fired (controlled) samples with the questioned evidence using optical comparison microscopes and, increasingly, automated identification systems.

Historical background

In 1912 Victor Balthazard demonstrated that barrel markings are unique to an individual barrel and produce a series of striations on any projectile passing through that barrel — a foundational observation for modern firearm identification. For decades examiners compared bullets and cartridge cases visually using comparison microscopes. Visual examination places heavy strain on the examiner's vision and is time-consuming, which motivated development of automated, digital systems to speed up comparison and indexing of ballistic evidence.

Early automated systems focused on bullets (initially called Bulletproof) and later were extended to cartridge cases and integrated into broader networks. Notable systems include IBIS (Integrated Ballistics Identification System) and national databases such as NIBIN (National Integrated Ballistic Information Network) in the United States.

IBIS — Integrated Ballistics Identification System

IBIS is an automated system (developed by Forensic Technology Inc. and widely deployed under ATF coordination) that acquires, stores and compares digital images of markings on bullets, cartridge cases and shotshells. It combines optical and electronic capture with pattern-matching algorithms to shortlist potential matches from large image databases.

How IBIS works

1. Data Acquisition Station (DAS) — photographs and captures surface images of bullets and cartridge cases. Laser optics focus on land and groove markings and the system records significant regions.
2. Image Analysis Station (Signature Analysis Station — SAS) — runs comparison algorithms. When a new image is entered the SAS searches stored images and returns a ranked list of candidate matches for an examiner to review.

IBIS produces candidate lists (correlation scores). Final confirmation is performed by an examiner using a comparison microscope.

Fig. 1 — Example: cartridge-case comparison on an IBIS workstation .

NBIS — NIST Ballistics Identification System (Congruent Matching Cells)

The National Institute of Standards and Technology (NIST) has developed advanced 3D topography measurement and correlation techniques, frequently referred to as NBIS in literature. A central contribution is the Congruent Matching Cells (CMC) method, which divides a 3D surface topography into multiple correlation cells and focuses comparison on valid, informative regions while discarding invalid or featureless regions. This reduces false correlations and speeds computation.

Congruent Matching Cells (CMC) — key ideas

• Divide the projectile's surface topography into many small cells to isolate valid correlation regions (cells that contain distinctive features).
• Quantify similarity between cells using metrics such as ACCF_max (Area Cross-Correlation Function maximum).
• Require consistent registration angles (θ) and consistent spatial distributions of matching cells across the surface.
• Declare a match when the CMC number (count of congruently matching cells) reaches a threshold (commonly cited as ≥ 6).

Fig. 2 — Schematic showing congruent matching cells on two topographies that originate from the same firearm.

Comparing IBIS and NBIS

Both IBIS and NBIS enable large-scale comparisons, but they differ in data capture, processing and openness of algorithms. IBIS traditionally captures high-quality 2D images and returns ranked candidates for human confirmation. NBIS leverages 3D topography and the CMC method to produce quantitative matching metrics and can be more robust to lighting variation and complex damaged samples.

IBIS	NBIS
Integrated Ballistics Identification System — commercial automated ballistics system.	NIST Ballistics Identification System — research and standards-driven approach with open methods.
Acquires 2D optical images of bullet and case surfaces.	Acquires 3D surface topographies and correlates topographic data.
Results depend heavily on lighting and imaging conditions (lighting direction, intensity, reflectivity).	3D topography reduces error from lighting variability and shadowing.
Algorithms and parameters are proprietary, limiting open inter-lab testing.	Algorithms and methods (e.g., CMC) are available for open testing and research, promoting inter-comparisons.
Typically compares against NIBIN / CIBIN databases and returns a ranked list for examiner review.	Compares against topography databases (e.g., NBTRD) and provides quantitative correlation metrics like CMC.

Both systems are valuable: automated matching narrows candidates and speeds investigation, but the final determination remains the responsibility of the trained examiner.

IBIS BULLETTRAX — advanced acquisition

BULLETTRAX is the bullet-acquisition component of IBIS that captures both 2D and 3D data around a bullet's circumference. It provides topographic detail, automatic surface tracking for damaged bullets, and an intuitive user interface that reduces operator training time.

Key BULLETTRAX features

• Custom 3D sensor technology: submicron topography capture, tolerant of imperfect mounting.
• Damaged and pristine bullets: intelligent surface-tracking acquires difficult samples in ~11–13 minutes.
• Simple mounting: customized stubs and easy jig for consistent mounting of many calibers.
• Pilot cameras: real-time view for setup and navigation of the bullet surface.
• Wide field of view: large context for analyzing deformed or fragmented bullets.
• Intuitive UI: step-by-step workflow that increases efficiency and consistency of acquisitions.

Conclusion

Automated systems such as IBIS and advanced topography-based methods like NBIS complement traditional microscopy by rapidly narrowing candidate matches from large collections of ballistic evidence. NBIS addresses some limitations of 2D optical methods (lighting, complex damage and open algorithmic evaluation), but no automated system wholly replaces the skill and judgment of an experienced examiner. These technologies are tools that improve throughput and focus expert attention — the final determination of a match remains a human decision.

References

1. Historical and foundational works on barrel rifling and firearm identification (e.g., Victor Balthazard, early 20th century).
2. Descriptions of IBIS / ATF and early automated systems (Drugfire, IBIS) in technical and forensic publications.
3. Information on NIBIN and CIBIN national ballistic networks and operational deployment.
4. Technical descriptions of IBIS workstation components (DAS and SAS) and operational workflows.
5. NIST research on Congruent Matching Cells (CMC) and NBIS topography-based methods; NBTRD — NIST Ballistics Toolmark Research Database.

© Forensic Ballistics Overview — compiled for instructional purposes.