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Open AccessArticle

Coastal Visibility Distance Estimation Using Dark Channel Prior and Distance Map Under Sea-Fog: Korean Peninsula Case

1
Daegu-Gyeongbuk Research Center, Electronics and Telecommunications Research Institute, Daegu 42994, Korea
2
Underwater Survey Technology (UST) 21, Incheon 21999, Korea
3
Division of Oceanographic Forecast, Korea Hydrographic and Oceanographic Agency, Busan 49111, Korea
*
Authors to whom correspondence should be addressed.
Sensors 2019, 19(20), 4432; https://doi.org/10.3390/s19204432
Received: 20 August 2019 / Revised: 10 October 2019 / Accepted: 10 October 2019 / Published: 13 October 2019
(This article belongs to the Section Remote Sensors, Control, and Telemetry)
Commercial visibility sensors among meteorological sensors estimate the visibility distance based on transmission, backward scattering, and forward scattering principle. These optical visibility sensors yield comparatively accurate local visibility distance. However, it is still difficult to obtain comprehensive visibility information for a wide area, such as the coast or harbor due to the sensor structure using straightness and scattering properties of light. In this paper, we propose a novel visibility distance estimation method using dark channel prior (DCP) and distance map based on a camera image. The proposed method improves the local limit of optical visibility sensor and detects the visibility distance of a wide area more precisely. First, the dark channel for an input sea-fog image is calculated. The binary transmission image is obtained by applying a threshold to the estimated transmission from the dark channel. Then, the sum of the distance values of pixels, corresponding to the sea-fog boundary, is averaged, in order to derive the visibility distance. This paper also proposes a novel air-light and transmission estimation technique in order to extract the visibility distance for an abnormal sea-fog image, including any light source, such as sunlight, reflection light, and illumination light, etc. The estimated visibility distance was compared with optical visibility distance of an optical visibility sensor and their agreement was evaluated. View Full-Text
Keywords: sea-fog; coastal visibility; dark channel prior; distance map; transmission sea-fog; coastal visibility; dark channel prior; distance map; transmission
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Bae, T.W.; Han, J.H.; Kim, K.J.; Kim, Y.T. Coastal Visibility Distance Estimation Using Dark Channel Prior and Distance Map Under Sea-Fog: Korean Peninsula Case. Sensors 2019, 19, 4432.

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