Image analysis – Applications – Surface texture or roughness measuring
Reexamination Certificate
1997-08-18
2001-04-17
Johns, Andrew W. (Department: 2621)
Image analysis
Applications
Surface texture or roughness measuring
C382S284000
Reexamination Certificate
active
06219437
ABSTRACT:
TECHNICAL FIELD
The invention relates to a system for the analysis and comparison of surfaces of fired bullets. The invention also relates to a method of analyzing and comparing the surfaces of fired bullets using the inventive system.
DESCRIPTION OF PRIOR ART
Forensic firearm examiners have to match bullets in order to determine if they have been fired from the same gun. Under present procedures, two bullets are placed under a comparison microscope, and the bullets are viewed at the same time by the examiner who compares the characteristics of their outer surfaces to determine if there is a match between them. As the reason for determining whether there is or is not a match is to present evidence in legal proceedings, the final step in the determination is normally performed by a human being who can subsequently appear as a witness in the legal proceeding. Nevertheless, the burden of the examiner could be greatly alleviated by an automated system for providing degree of match between pairs of bullets. Such system would preferably be an optoelectronic system.
Optoelectronic systems for comparing bullets are known in the prior art as at, for example, U.S. Pat. No. 3,680,966, Cofek et al, Aug. 1, 1972. However, the Cofek et al apparatus examines the flash hole of cartridge cases after manufacture but before firing.
U.S. Pat. No. 3,780,614, Maier, Dec. 25, 1973, teaches a multiple bullet and cartridge holder for forensic microscopes which provide improved indexing and manipulation.
The problem is also addressed in COMPUTER IDENTIFICATION AND CLASSIFICATION OF BULLETS, a Dissertation Submitted in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy (Electrical Engineering) at the Polytechnic Institute of New York by Geoffrey Y. Gardner, June 1976.
SUMMARY OF INVENTION
It is therefore an object of the invention to provide a method for obtaining a signature from a fired bullet, comprising the steps of: a) mounting the bullet to turn substantially about a longitudinal axis thereof; b) illuminating a surface portion of said bullet; c) obtaining and storing a frame image at a given position of said surface portion using microscope optics, said frame image having a transverse extent substantially transverse to said longitudinal axis; d) advancing said position by an amount less than a transverse extent of the frame image; e) repeating the steps (c) and (d) a plurality of times to obtain a plurality of overlapping frame images; f) combining the frame images to form a continuous composite image having a transverse extent much greater than said transverse extent of said frame images; and g) computing a signature of the composite image along a line extending in said transverse extent of the composite image, wherein points of the signature are determined from image data along a direction of striations in said composite image, The direction is at an angle with respect to the transverse line and the longitudinal axis.
Preferably, step (f) comprises positioning each additional one of the frame images in at least one direction, the one direction being along the transverse extent, until overlapping portions of the additional frame image and the composite image match, and adding to the composite image a non-overlapping portion of the additional frame image.
The invention also provides an apparatus for obtaining a signature from a fired bullet, comprising: means for rotatably mounting the bullet to turn substantially about a longitudinal axis of the bullet; means for illuminating a surface portion of the bullet; means for obtaining and storing a frame image at a given position of the surface portion using microscope optics, the frame image having a transverse extent substantially transverse to the longitudinal axis; motor means for advancing the position by an amount less than a transverse extent of the frame image; means for combining a plurality of the frame images to form a continuous composite image having a transverse extent much greater than the transverse extent of the frame images; and means for computing a signature of the composite image along a line extending in the transverse extent of the composite image, wherein points of the signature are determined from image data along a direction of striations in the composite image, the direction being at an angle with respect to the line and the longitudinal axis.
REFERENCES:
patent: 3680966 (1972-08-01), Cofek et al.
patent: 3712466 (1973-01-01), Aubry et al.
patent: 3780614 (1973-12-01), Maier
patent: 3800074 (1974-03-01), Fletcher et al.
patent: 4923066 (1990-05-01), Ophir et al.
patent: 5134661 (1992-07-01), Reinsch
patent: 5140647 (1992-08-01), Ise et al.
patent: 5214713 (1993-05-01), Juvinall
patent: 5390108 (1995-02-01), Baldur et al.
patent: 5659489 (1997-08-01), Baldur
IEE Colloquim on Electronic Images and Image Processing in Security and Forensic Science Digest #087, abstract only, May 1990.*
NTIS Report #NASA-CR-139371, Contract #NAS7-100, abstract only, Jul. 1974.*
Arndt et al, “Bullet Signature Identification Using Time Domain Computer Techniques”, Proceedings of Int. Carnahan Conf. pp. 145-151, 1983.*
Unitech Inc., “Ballistic Signature Identification System Study”, Report #NASA-CR-147820, Contract #NAS9-14708, 40 pages, May 1976.*
Arndt, G.D., “Ballistic Signature Identification . . . ”, 1977 Caarnahan Conf. on Crime Countermeasures, p. 235, abstract only.*
Gardner, G.Y., “Computer Identification of Bullets”, 1977 Carnahan Conf. on Crime Countermeasures, pp. 149-166.*
Identification and Classification of Bullets, Dissertation, Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (Electrical Engineering) at the Polytechnic Institute of New York, by Geoffrey Y. Gardner, Jun. 1976.
Cantor & Colburn LLP
Forensic Technology (Wai) Inc.
Johns Andrew W.
LandOfFree
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