摘要：The spatial resolution improvement of orbital sensors has broadened considerably the applicability of their images in solving urban areas problems. But as the spatial resolution improves, the shadows become even a more serious problem especially when detailed information (under the shadows) is required. Besides those shadows caused by buildings and houses, clouds projected shadows are likely to occur. In this case there is information occlusion by the cloud in association with low illumination and contrast areas caused by the cloud shadow on the ground. Thus, it’s important to use efficient methods to detect shadows and clouds areas in digital images taking in count that these areas care for especial processing. This paper proposes the application of Mathematical Morphology (MM) in shadow and clouds detection. Two parts of a panchromatic QuickBird image of Cuiabá-MT urban area were used. The proposed method takes advantage of the fact that shadows (low intensity – dark areas) and clouds (high intensity – bright areas) represent the bottom and top, respectively, of the image as it is thought to be a topographic surface. This characteristic allowed MM area opening and closing operations to be applied to reduce or eliminate the bottom and top of the topographic surface.
其他摘要：The spatial resolution improvement of orbital sensors has broadened considerablythe applicability of their images in solving urban areas problems. But as the spatialresolution improves, the shadows become even a more serious problem especiallywhen detailed information (under the shadows) is required. Besides those shadowscaused by buildings and houses, clouds projected shadows are likely to occur. Inthis case there is information occlusion by the cloud in association with lowillumination and contrast areas caused by the cloud shadow on the ground. Thus,it’s important to use efficient methods to detect shadows and clouds areas in digitalimages taking in count that these areas care for especial processing. This paperproposes the application of Mathematical Morphology (MM) in shadow and cloudsdetection. Two parts of a panchromatic QuickBird image of Cuiabá-MT urban areawere used. The proposed method takes advantage of the fact that shadows (lowintensity – dark areas) and clouds (high intensity – bright areas) represent thebottom and top, respectively, of the image as it is thought to be a topographicsurface. This characteristic allowed MM area opening and closing operations to beapplied to reduce or eliminate the bottom and top of the topographic surface.
关键词：Morfologia Matemática;Detecção de Sombras;Detecção de Nuvens;Imagem de Alta Resolução;Mathematical Morphology;Shadows detection;Cloud Detection;High Resolution Imagery
