Shape measurement tools in footwear analysis: a statistical investigation of accidental characteristics over time.
Presence of accidental characteristics on footwear strengthens the linkage of a given piece of footwear to a footwear impression left at a crime-scene. Thus an understanding of rate of appearance and disappearance of these characteristics is of importance. Artificial cut-marks, 1-3mm in depth, were cut into outsoles of 11 pairs of athletic shoes. Loss of these cut-marks and acquisition of new accidental characteristics/wear patterns were monitored over a seven-week time-span. Feature-vector methods were used to acquire multivariate data on wear/acquisition rates. A repeatability study indicated the feature vector method could detect small differences among shoes relative to measurement uncertainty. The shoes displayed a strong retention of artificial cut-marks over the study interval. Net rate of wear was 0.1% of the textured area of the shoe per week, predominantly in the heel and ball area. Results indicate accidental characteristics can reasonably be expected to persist over time.
Department of Physics, Canisius College, 2001 Main Street, Buffalo, NY 14208, United States.
H David
HD
Sheets
Susan
S
Gross
Glenn
G
Langenburg
Peter J
PJ
Bush
Mary A
MA
Bush
Accidental characteristics; Accidentals; Feature vector methods; Footwear; Forensic science; Shoes