Dimensional Review of Scales for Forensic Photography |
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| Authors: | Massimiliano Ferrucci M.S. Theodore D. Doiron Ph.D. Robert M. Thompson B.S. John P. Jones M.B.A. II Adam J. Freeman D.D.S. Janice A. Neiman B.S. |
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| Affiliation: | 1. Dimensional Metrology Group, National Institute of Standards & Technology (NIST), Gaithersburg, MD;2. Special Programs Office, National Institute of Standards & Technology, Gaithersburg, MD;3. Westport Dental Associates, Westport, CT;4. Massachusetts Office of the Commissioner of Probation, Massachusetts Trial Court, Boston, MA |
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| 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. |
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| Keywords: | forensic science photography scales quality odontology bitemark |
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