Small target visibility (STV) is used as a quality criterion in roadway lighting and is the recommended design practice in North America. This paper briefly describes the principle of STV and the concept of measurement using spatial analysis. A Charge-Coupled Device (CCD) camera takes an image of the scene of interest. Applying information theory an analysis of the pixel content is performed and the signal processing involves a multitude of mathematical calculations. This method is devised to capture the luminance of an arbitrary road scene. An algorithm is applied to calculate the spatial frequency of the pixel content that serves as a measure which characterizes the visibility in the roadway scene without a need for a target to be inserted. The images are processed using MATLAB software. The results of the analysis of a few roadway scenes will be presented in this paper. This project is the first step in constructing a device capable of measuring target visibility in a scene by a handheld computer system that performs a Fourier spatial frequency analysis and also determines relative average background luminance. The meter shall meet the following requirements: - Usable in the field - Easily transportable User friendly - Battery powered.
Small target visibility (STV) meter that performs spatial analysis of road scenes
Kleinzielsichtgerät (STV) für die räumliche Analyse von Straßenszenen
2003
9 Seiten, 6 Bilder, 8 Quellen
Conference paper
English
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