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Proceedings Paper

Automated detection and removal of cloud shadows on HICO images
Author(s): Ruhul Amin; Richard Gould; Weilin Hou; Zhongping Lee; Robert Arnone
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Paper Abstract

Clouds cause a serious problem for optical satellite sensors. Clouds not only conceal the ground, they also cast shadows, which cause either a reduction or total loss of information in an image, by reducing the illumination falling on the shadowed pixels. Ocean color bio-optical inversion algorithms rely on measurements of remote sensing reflectance (Rrs (λ )) at each pixel. If shadows are not removed properly across a scene, erroneous Rrs (λ) values will be calculated for the shadowed pixels, leading to incorrect retrievals of ocean color products such as chlorophyll. The cloud shadow issue becomes significant especially for high-resolution sensors such as the Hyperspectral Imager for the Coastal Ocean (HICO). On the other hand, the contrast of pixels in and outside a shadow provides opportunities to remove atmospheric contributions for ocean color remote sensing. Although identifying cloud is relatively straightforward using simple brightness thresholds, identifying their shadows especially over water is quite challenging because the brightness of the shadows is very close to the brightness of neighboring sunny regions especially in deep waters. In this study, we present automated procedures for our recently proposed cloud shadow detection technique called the Cloud Shadow Algorithm (CSA) and Lee et al. (2007) cloud and shadow atmospheric correction algorithm. We apply both automated procedures to HICO imagery and show examples of the results.

Paper Details

Date Published: 4 May 2011
PDF: 10 pages
Proc. SPIE 8030, Ocean Sensing and Monitoring III, 803004 (4 May 2011); doi: 10.1117/12.887761
Show Author Affiliations
Ruhul Amin, U.S. Naval Research Lab. (United States)
Richard Gould, U.S. Naval Research Lab. (United States)
Weilin Hou, U.S. Naval Research Lab. (United States)
Zhongping Lee, Mississippi State Univ. (United States)
Robert Arnone, U.S. Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 8030:
Ocean Sensing and Monitoring III
Weilin W. Hou; Robert Arnone, Editor(s)

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