Automated Mobile Highway Sign Retroreflectivity Measurement


This paper presents a mobile image-based system for measuring the brightness of highway signs at night time, so that visibility standards for sign can be evaluated and maintained to protect the safety of the motoring public. The system is composed of a high speed IEEE-1394 digital camera, and a laptop computer with a purpose-designed measuring software, which is composed of three modules:1) Image and video processing; 2) Image analysis; 3) data storage. Using vehicle headlamps as an illumination source, the system can acquire, classify, and analyze the visibility of the traffic signs in real time, and report results to a data file. The analysis algorithms, including elements of sign isolation, classification, and intensity measurement, are designed for easy implementation and fast real-time measurement. The results of static testing experiments on signs, and on-road real time measurements are describe in this paper and they show the feasibility of such a system.

Meeting Name

Artificial Neutral Networks in Engineering Conference:Smart Engineering System Design (2002: Nov. 10-13, St. Louis, MO)


Geosciences and Geological and Petroleum Engineering

Second Department



University of Missouri--Rolla. Center for Infrastructure Engineering Studies
Missouri. Department of Transportation
National Cooperative Highway Research Program

Keywords and Phrases

Algorithms; Cameras; Data storage equipment; Image analysis; Laptop computers; Light reflection; Traffic signs; Retroreflectivity; Imaging systems

Document Type

Article - Conference proceedings

Document Version


File Type





© 2002 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Nov 2002

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