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Benefits of Combining 2D and 3D Images
Benefits of Combining 2D and 3D Images
Early ballistic image collection used 2D technology, similar to thecomparison microscope, for use in automated ballistic identificationsystems. Technological innovation now enables the precise captureof 3D topography on bullets and cartridge cases.
The March 2008 U.S. National Research Council of the NationalAcademies report on Ballistic Imaging describes a trade-offbetween 2D and 3D, with both approaches showing goodperformance. IBIS® is dealing with this trade-off by combiningthe strengths of both 2D and 3D in its IBIS® TRAX-3DTM products.
Our studies on bullet comparisons revealedthe following performance benefits:
Correlation performance research on large databases indicatescomplementary benefits, attributable to imaging 2D textureinformation combined with microscopic 3D topography information.
- 10% increase in performance with standalone 3D comparison compared to standalone 2D comparison.
- 15% increase in performance with combined 2D and 3D comparison compared to standalone 3D comparison.
Therefore, a potential increase of 25% is expected, which isconsidered very significant in this field.
Furthermore, 3D information can help match bullet pairs that arechallenging with just 2D images or with a comparison microscope.The additional value of 3D is especially significant when comparingbullets with different material compositions.
A study published by the American Academy of Forensic Sciencesin the Journal of Forensic Sciences1 revealed that 3D provided aconsiderable performance increase for the comparison of lead bulletsagainst copper jacketed bullets:
Superior visualization is achieved by overlaying the 2D textureover the rendered 3D model with an adjustable simulated lightsource. This combination allows dynamic observation of the surfaceinformation by adjusting the mix of 2D texture and 3D topographyrendering. The resulting 2D-3D mixed panoramic digital imagemost closely resembles what firearm examiners see underthe comparison microscope with the physical evidence.
1 (Toni B. Brinck M.Sc. (2008) Comparing the Performance of IBIS andBulletTRAX-3D Technology Using Bullets Fired Through 10 ConsecutivelyRifled Barrels. Journal of Forensic Sciences 53 (3) , 677–682doi:10.1111/j.1556-4029.2008.00702.x)
“These results suggest that [IBIS TRAX-3D]is more effective than [IBIS Heritage] inthe analysis of a wider range of bullettypes and it was also found to produceimages of superior quality.”
Benefits of Combining 2D and 3D Images
The addition of 3D information to automated ballistic identification toolsserves two useful purposes:
1. Provides a macroscopic level of detail for visualizing and analyzing the general shape of exhibits. This requires a depth resolution in the order of tens of microns.
2. Provides a microscopic level for the depth measurementsof markings and striae, to allow an optimal digital comparisonand the analysis of fine surface details. This requires a depth resolution at the sub-micron level for bullets and a resolution at the micron level for cartridge cases.
The following figure shows a side-by-side view of two bullets, with the 2D texture on the left and the 3D topography rendering on theright. The 3D measured depth profile represents the cross-sections where the two bullets meet in the side-by-side view.
Figure 1 - 2D texture (left) and 3D topography rendering (right) of the same two side-by-side bullets
Microscopic 3D measurements of the surface topography allow the exploration of new scientific methods to support analyticalconclusions. Forensic Technology continuously strives to utilize the best of technology to meet the needs of ballistic experts and providesolutions for a safer society.
For any questions, please contact us at [email protected]
Bullet A Bullet B Bullet A Bullet B
