Method and apparatus for alignment, comparison & identification of characteristic tool marks, including ballistic signatures

• US 20060177104A1
• Filed: 12/28/2005
• Published: 08/10/2006
• Est. Priority Date: 06/10/1998
• Status: Active Grant

• Current Assignee: Francine J. Prokoski
• Original Assignee: Francine J. Prokoski
• Inventors: Prokoski, Francine J.
• Granted Patent: US 7,602,938 B2
• Time in Patent Office: Days
• US Class Current: 382/108
• CPC Class Codes: F42B 35/00 Testing or checking of ammunition apparatus for measuring the energy of projectiles G01L5/14
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection

Abstract

Systematic use of infrared imaging characterizes marks made on items and identifies the particular marking tool with better accuracy than use of visual imaging. Infrared imaging performed in total darkness eliminates shadows, glint, and other lighting variations and artifacts associated with visible imaging. Although normally used to obtain temperature measurements, details in IR imagery result from emissivity variations as well as thermal variations. Disturbing an item'"'"'s surface texture creates an emissivity difference producing local changes in the infrared image. Identification is most accurate when IR images of unknown marks are compared to IR images of marks made by known tools. However, infrared analysis offers improvements even when only visual reference images are available. Comparing simultaneous infrared and visual images of an unknown item, such as bullet or shell casing, can detect illumination-induced artifacts in the visual image prior to searching the visual database, thereby reducing potential erroneous matches.

Claims

1. Method for characterizing a ballistic item including the steps:

a. Produce a sequence of digitized passive infrared images of the item at different focus points such that the deepest to the highest features are each in sharp focus in at least one image;

b. tag each image with the ID of the item;

c. tag each image with specifics of the imaging set-up including the focus position, and size of digitized image array;

d. store the tagged image sequence in a database.

2. Method of claim 1 with the additional step:

e. produce a photomontage from the tagged image sequence in which each section of the montage image is the corresponding section of the image from the tagged sequence in which that section is in sharpest focus.

3. Method of claim 1 with the additional step of replacing each tagged image in the sequence with a tagged extracted feature image containing only features at least a specified size extracted from the tagged image.

4. Method of claim 1, further comprising steps:

adding to each tag weapon-specific ancillary information including calibre, type of ammunition, direction of twist, number of lands, serial number; and

adding to each tag incident-specific information including type of crime committed, location where item was found, associated names, method of crime.

5. Method for identification of a ballistic item including the steps:

a. characterize the unknown ballistic item by producing a tagged image sequence

b. compare the image sequence with those contained in a database

c. determine those sequences in which one or more images are similar to the unknown tagged image sequence

d. display the similar pair(s) of images to a ballistics examiner who reviews the display and rules that the unknown ballistic item is a match to an item in the database if the similar pair(s) of images are sufficiently alike.

6. Method of claim 5, wherein step d is performed automatically by further image processing.

7. Method of claim 5 step, further comprising the steps:

comparing the weapon-specific and incident-specific tagging information of the similar image pair(s);

displaying the similarities and dissimilarities in the tagging information along with the images for further consideration by a ballistics examiner who reviews the display and rules that the unknown ballistic item is a match to an item in the database if the tagging information as well as the similar pair(s) of images are sufficiently alike.

8. Method of claim 7 wherein the reviewing by the ballistics examiner is performed automatically by further image processing.

9. Method for identification of a ballistic item including the steps:

a. characterize the unknown ballistic item by producing from passive infrared images a tagged extracted feature sequence;

b. compare the extracted feature sequence with those contained in a database;

c. determine those sequences in which one or more extracted features are similar to the unknown extracted feature sequence;

d. display the similar pairs of extracted features to a ballistics examiner who reviews the display and rules that the unknown ballistic item is a match to an item in the database if the similar pair(s) of extracted features are sufficiently alike.

10. Method of claim 9, wherein the reviewing by the ballistics examiner is performed automatically by further image processing.

11. Method of claim 9, further comprising the steps:

comparing the weapon-specific and incident-specific tagging information of the similar extracted feature pair(s); and

comparing the similarities and dissimilarities in the tagging information along with the extracted features for further consideration by a ballistics examiner who reviews the display and rules that the unknown ballistic item is a match to an item in the database if the tagging information as well as the similar pair(s) of extracted features are sufficiently alike.

12. Method of claim 11, wherein said comparing step is performed automatically by further image processing.

13. Method of claim 1, further comprising the steps:

heating or cooling the ballistic item to vary its temperature;

producing an image sequence in which both focus and temperature are varied; and

tagging each image with the corresponding temperature.

14-17. -17. (canceled)

18. Method to detect residue on a ballistic item, including the steps:

a. apply a sequence of spectral filters to the IR camera;

b. for each filter, vary the focus to produce an image sequence of passive infrared images;

c. extract features from each image in the sequence;

d. compare the feature sets in images which have the same focus setting but different spectral filters;

e. display those features which are filter-sensitive as possible residue;

f. Annotate features with likely type of residue based upon the filter sensitivity.

19. Apparatus for characterizing a ballistic item including:

a. IR camera with lenses and focus control;

b. Mechanism for varying the focus control to produce a sequence of images;

c. Image digitizer and storage;

d. Mechanism for tagging images with ancillary information;

e. Feature extractor;

f. Processor for characterizing the features;

g. Processor for creating a montage;

h. Display;

i. Mechanism for positioning the item within the camera field of view.

20. The apparatus of claim 19 including also the elements:

j. device for heating the ballistic item;

k device for measuring the temperature of the ballistic device;

l. device for applying optical filters before the camera lens;

m. mechanism for tagging the resulting images with temperature and filter data.

21. Apparatus for identifying a ballistic item including the elements of 20 plus:

n. Database of characterized ballistic items;

o. Database matching engine;

p. Output or display mechanism.

22. Method for identifying a ballistic item including the steps

a. for each montaged infrared image derived from an unknown item database and a known item database produce a relative location map as follows:

b. compute the centroid location for each feature, including all striations, gouges, breech face marks, and firing pin indents, where each striation is considered a separate feature;

c. Compute the distances between each pair of centroids;

d. Tag the distances with the type of feature represented at each end;

e. Match the list of tagged distances with corresponding lists for the known item database.

23. Method for separating manufacturers marks from weapons marks in ballistic images, including the steps:

a. heating the ballistic item to enhance the manufacturers marks;

b. producing a passive infrared image of the ballistic item;

c. producing a template of the areas containing the enhanced manufacturers marks; and

d. extracting the template areas to form an image containing the manufacturers marks,

wherein the remaining image contains no manufacturers marks but contains weapons marks which did not overlay manufacturers marks.

24. Method for estimating the volume of groves, indentations and striations in ballistic items including the steps:

a. heat the ballistic item to an elevated temperature;

b. measure the mean temperature of the item using a radiometric infrared camera;

c. capture a sequence of passive infrared images as the item cools;

d. capture for each image the mean temperature using the radiometric camera;

e. estimate the volume of each depressed feature by determining its heat loss rate relative to the mean temperature of the item, considering also the materials composition of the item.