This study proposes an estimation method of road visibility using digital camera images. The weighted intensity of power spectrum (WIPS) has been examined in terms of its applicability as a visibility assessment value. The magnitude of WIPS represented the difference in spatial frequencies within the image based on human contrast sensitivity function. An experiment was carried out to propose a new image-based method of assessing visibility on the road during fog. For the experiment a laboratory where artificial fog can be generated on the scale of a real road was used. A digital still camera captured images, and a personal computer simultaneously recorded illuminance and transmissivity under fog. The subjects assessed the visibility of the target using their foveal vision. The study objectives were: a) To develop an image-based visibility assessment method and to clarify the relationship between the subjective visibility assessment value and the magnitude of WIPS under foggy condition. b) To propose a system that can provide visibility information to the driver and the highway administrator using digital images recorded by the roadside TV cameras. The experiment was conducted in a laboratory of the National Institute for Land and Infrastructure Management in Tsukuba, Japan. The laboratory was selected mainly because it allows comparison between subjective assessment (by test subjects) and objective indexes by measurement methods. It was carried out from December 8 to 12, 2002. The laboratory contains a full-scale test road 200 m long, 10 m wide, and 10 m high. The road runs through a transparent tunnel. The visual range of the test road can be set between 20 m and 200 m by controlling the steam generating system and water nozzles. One woman and seven men, all in their twenties, participated as test subjects.
Proposed a new method to assess poor visibility level on roads by digital images
Vorschlag einer neuen Methode für die Abschätzung der Sichtweite auf Verkehrsstrassen mittels Digitalbildern
2005
10 Seiten, 5 Bilder, 3 Quellen
Conference paper
English
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