Road Weather Management Program
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Best Practices for Road Weather Management Version 2.0


Atmospheric Visibility Measurements using Video Cameras: Relative Visibility


The objective of this research was to advance the visibility measurement technologies that compute visibility through processing images captured by video cameras. There are fundamental difficulties in measuring visibility. A solution presented in this report is to measure visi using visual propereties of video image (perceived info) instead of indirectly measuring physical properties of atmosphere and converting them to visi. The spatial variance problem in visibility was solved by introducing a new concept of relative measurement of visual information referred to as Relative Visibility (RV). This report also includes a study result on the limitation of CCD cameras in visibility measurement applications, and shows how to overcome them through spatially arranged multiple targets. In addition, various apparatuses of Near Infrared (NIR) light source and cameras for measuring night visibility were explored.


University of Minnesota Duluth, Department of Electrical and Computer Engineering; Prepared for Minnesota DOT

Date: 2004





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