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TitleA spatial-spectral methodology to detect narrow shadows on satellite imagery: a case study of Calgary, Canada
AuthorZhang, Y; Guindon, B
SourcePhotogrammetric Engineering and Remote Sensing vol. 79, no. 3, 2013 p. 269-276,
Alt SeriesEarth Sciences Sector, Contribution Series 20120336
PublisherAmerican Society for Photogrammetry and Remote Sensing
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS-114.5000 -114.0000 51.2500 51.0000
Subjectsgeophysics; satellite imagery; remote sensing
Illustrationssatellite imagery; satellite images; flow charts
ProgramRemote Sensing Science, Program Leadership
AbstractImage shadow is an important mono-scope cue in the detection and characterization of buildings from aerial and satellite
imagery. Previous studies have confi rmed the effectiveness of radiometric thresholding in delineating shadows cast by tall
buildings on high resolution (\'021m) imagery. Thresholding is not effective when shadow width is comparable to the imaging
sensor resolution since mixed shadow/illuminated pixels do not exhibit a distinct radiometric character. A spatial-spectral
shadow detection method is proposed that exploits the line-like and low radiance characteristics of shadows cast by large area
commercial/industrial buildings commonly found in suburban areas of large cities. Tests conducted in shadow detection
of such buildings in Calgary, Alberta using RapidEye imagery indicate that detectability rates of ~80 percent can be achieved
although commission errors are signifi cant because of the plethora of other line-like features present in industrial park settings.