toward automatic blood spatter analysis in crime scenes
DESCRIPTION
Toward Automatic Blood Spatter Analysis in Crime Scenes. Gabriel Brostow, 13 June, 2006. Shen, Brostow, Cipolla University of Cambridge. Bloodstain Categories*. Passive Bloodstains Projected Bloodstains Low / medium / high velocity impact: caused by force applied to a blood source - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/1.jpg)
Toward Automatic Blood Spatter Analysis in Crime
Scenes
Gabriel Brostow, 13 June, 2006
Shen, Brostow, CipollaUniversity of Cambridge
![Page 2: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/2.jpg)
Bloodstain Categories*
• Passive Bloodstains
• Projected Bloodstains– Low / medium / high velocity impact:
caused by force applied to a blood source
• Transfer/Contact Bloodstains
*International Association of Bloodstain Pattern Analysts
![Page 3: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/3.jpg)
![Page 4: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/4.jpg)
Image by Kevin Maloney
![Page 5: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/5.jpg)
Point of Origin Localization
![Page 6: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/6.jpg)
String Method
![Page 7: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/7.jpg)
Support Software
From BackTrack software by A. L. Carter, 2001 version
![Page 8: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/8.jpg)
Automation Goals
1. Estimate impact angles for 1 spot
2. Estimate 2D origin of impact
3. Estimate 3D origin of impact
![Page 9: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/9.jpg)
Automation Goals
1. Estimate impact angles for 1 spot
2. Estimate 2D origin of impact
3. Estimate 3D origin of impact
![Page 10: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/10.jpg)
![Page 11: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/11.jpg)
Experimental Setup
![Page 12: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/12.jpg)
Results: Impact Angles
![Page 13: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/13.jpg)
Primary vs. Secondary Stains
Bevel & Gardner, 2001
![Page 14: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/14.jpg)
Filter for Outliers
![Page 15: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/15.jpg)
Automation Goals
1. Estimate impact angles for 1 spot
2. Estimate 2D origin of impact
3. Estimate 3D origin of impact
![Page 16: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/16.jpg)
2D Multi-Spot Analysis
• Experiment– Blunt force impact– True origin:
• diameter 6cm• height 22cm
![Page 17: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/17.jpg)
Strings in the form of vectors
x
y
![Page 18: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/18.jpg)
Intersections
![Page 19: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/19.jpg)
Convolve with Gaussian
![Page 20: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/20.jpg)
Threshold on Distance
![Page 21: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/21.jpg)
Image rectification
• Generate synthetic view
• Homography:
![Page 22: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/22.jpg)
Image rectification
![Page 23: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/23.jpg)
Automation Goals
1. Estimate impact angles for 1 spot
2. Estimate 2D origin of impact
3. Estimate 3D origin of impact
![Page 24: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/24.jpg)
![Page 25: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/25.jpg)
![Page 26: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/26.jpg)
![Page 27: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/27.jpg)
![Page 28: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/28.jpg)
![Page 29: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/29.jpg)
Height Estimation
• Triangulation– H = tan() * distance– True height 22cm,
estimated height 19cm
• Advanced– Unknowns– Speed, distance, air
resistance and gravity
![Page 30: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/30.jpg)
Height Estimation
• Triangulation– H = tan() * distance– True height 22cm,
estimated height 19cm
• Model in future– Speed, distance, air
resistance and gravity
![Page 31: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/31.jpg)
Findings
• Demonstrated accuracy of 1-spot analysis
• 2D Origin of Impact Estimation
• Overhead crime-scene visualization
• Groundwork for 3D string method automation
![Page 32: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/32.jpg)
Future Work
• Real blood images
• 3D projectile trajectory modeling
![Page 33: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/33.jpg)
![Page 35: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/35.jpg)
![Page 36: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/36.jpg)
Related work
• Interpretation of Bloodstain Evidence at Crime Scenes – Eckert & James, 1998
• Bloodstain Pattern Analysis– Bevel & Gardner, 2001
• Blood Dynamics– Wonder, 2001
• The Directional Analysis of Bloodstain Patterns, Theory and Experimental Validation– A.L.Carter, 2001
![Page 37: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/37.jpg)
Alternative bloodstain ellipse fitting
• Alternative ellipse fitting algorithm– Ellipse growth– Erosion, median filter
and dilation
![Page 38: Toward Automatic Blood Spatter Analysis in Crime Scenes](https://reader035.vdocument.in/reader035/viewer/2022062407/56812ead550346895d94510a/html5/thumbnails/38.jpg)
Manual vs. Automatic
• Current pipeline:– On-site measurements– Physical strings
construction– Qualitative estimation
of origin
• Automatic pipeline:– Image processing– Strings in the form of
equations stored on computer
– Quantitative estimation of origin using error functions