| Title | A robust approach for object-based detection and radiometric characterization of cloud shadow using haze optimized transformation |
| Author | Zhang, Y; Guindon, B; Li, X |
| Source | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing vol. 52, issue 9, 2014 p. 5540-5547, https://doi.org/10.1109/TGRS.2013.2290237 |
| Year | 2014 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130474 |
| Publisher | Institute of Electrical and Electronics Engineers (IEEE) |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Subjects | geophysics; remote sensing; satellite imagery |
| Illustrations | plots; satellite images; flow charts; histograms |
| Program | Remote Sensing Science, Methodology |
| Abstract | Cloud shadows in satellite imagery hinder understanding of ground surface conditions due to reduced illumination and the potential for confusion with illuminated low-reflectance objects such as water
bodies. This paper extends the application of the haze optimized transform (HOT) from haze mapping to include object-oriented detection of clouds and cloud shadows. An integrated processing chain encompassing these tasks has been implemented and
successfully applied to Landsat Enhanced Thematic Mapper Plus and Multispectral Scanner imagery covering a variety of land covers and landscapes. The results confirm that the HOT-based method for cloud shadow detection is robust and effective. Cloud
shadows have been identified and extracted with overall accuracy of about 95.3%. Clear-sky dark pixels (e.g., small lakes) are well separated from cumulus cloud shadow pixels. The spatial distribution of HOT response in a given cloud patch can be
used to estimate the extent and variation of incoming visible radiation reduction in its corresponding shadow patch. This information, in turn, has been used to apply a radiometric gain to compensate for the shadowing effect on the land. The HOT
response has been tested for radiometric characterization of cloud shadows and subsequent shadow illumination compensation. |
| Summary | (Plain Language Summary, not published)
Cloud shadows appear as dark patches in optical satellite imagery. These shadows are easily confused with other features such as water bodies, and
therefore can hinder the extraction of information from an image. This can limit the utility of the image. This work extends the application of a method used to detect haze in satellite images to the detection of cloud shadows. A methodology was
developed and successfully applied to imagery covering a variety of land covers and landscapes. The results confirm that the new method for cloud shadow detection is robust and effective. Cloud shadows have been identified and extracted with an
overall accuracy of approximately 95.3%. Clear-sky dark areas (e.g. small lakes) are well separated from cloud shadows. |
| GEOSCAN ID | 293691 |
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