TITLE:
Minimum Requirements for Taxicab Security Cameras
AUTHORS:
Shengke Zeng, Harlan E. Amandus, Alfred A. Amendola, Bradley H. Newbraugh, Douglas M. Cantis, Darlene Weaver
KEYWORDS:
Taxicab Homicide, Facial Identification, Photographic Resolution, Dynamic Range, Lens Distortion, Motion Blur
JOURNAL NAME:
Journal of Transportation Technologies,
Vol.4 No.3,
July
31,
2014
ABSTRACT:
Problem: The homicide rate of taxicab-industry is 20 times greater than
that of all workers. A NIOSH study showed that cities with taxicab-security
cameras experienced significant reduction in taxicab driver homicides. Methods:
Minimum technical requirements and a standard test protocol for
taxicab-security cameras for effective taxicab-facial identification were determined.
The study took more than 10,000 photographs of human-face charts in a
simulated-taxicab with various photographic resolutions, dynamic ranges,
lens-distortions, and motion-blurs in various light and cab-seat conditions.
Thirteen volunteer photograph-evaluators evaluated these face photographs and
voted for the minimum technical requirements for taxicab-security cameras. Results:
Five worst-case scenario photographic image quality thresholds were suggested: the
resolution of XGA-format, highlight-dynamic-range of 1 EV,
twilight-dynamic-range of 3.3 EV, lens-distortion of 30%, and shutter-speed of
1/30 second. Practical
Applications: These minimum requirements will help taxicab regulators and
fleets to identify effective taxicab-security cameras, and help taxicabsecurity
camera manufacturers to improve the camera facial identification capability.