title: Dimensional Review of Scales for Forensic Photography.
abstract: Scales for photography provide a geometrical reference in the photographic documentation of a crime scene, pattern, or item of evidence. The ABFO No. 2 Standard Reference Scale (1) is used by the forensic science community as an accurate reference scale. We investigated the overall accuracy of the major centimeter graduations, internal/external diameters of the circles, error in placement of the circle centers, and leg perpendicularity. Four vendors were selected for the scales, and the features were measured on a vision-based coordinate measurement system. The scales were well within the specified tolerance for the length graduations. After 4 years, the same scales were measured to determine what change could be measured. The scales demonstrated acceptable stability in the scale length and center-to-center measurements; however, the perpendicularity exhibited change. The study results indicate that scale quality checks using certified metal rulers are good practice.
authors.affiliation: Dimensional Metrology Group, National Institute of Standards & Technology (NIST), 100 Bureau Drive, Mail Stop 8102, Gaithersburg, MD.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Ferrucci
authors.affiliation: Dimensional Metrology Group, National Institute of Standards & Technology (NIST), 100 Bureau Drive, Mail Stop 8102, Gaithersburg, MD.
authors.forename: Theodore D
authors.initials: TD
authors.lastname: Doiron
authors.affiliation: Special Programs Office, National Institute of Standards & Technology, 100 Bureau Drive, Mail Stop 8102, Gaithersburg, MD.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Thompson
authors.affiliation: Special Programs Office, National Institute of Standards & Technology, 100 Bureau Drive, Mail Stop 8102, Gaithersburg, MD.
authors.forename: John P
authors.initials: JP
authors.lastname: Jones
authors.affiliation: Westport Dental Associates, 22 Imperial Avenue, Westport, CT.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Freeman
authors.affiliation: Massachusetts Office of the Commissioner of Probation, Massachusetts Trial Court, 1 Ashburton Place, #405, Boston, MA.
authors.forename: Janice A
authors.initials: JA
authors.lastname: Neiman
keywords: bitemark; forensic science; odontology; photography; quality; scales