A building shadow extraction processing method for a sentinel 2A image

Abstract

The invention discloses a building shadow extraction processing method for a sentinel 2A image, and the method comprises the steps of S1, extracting the main ground feature component of an urban area,designing a shadow enhancement index based on a sentinel 2A original spectrum to enhance a building shadow; calculating a normalized difference water body index to enhance the water body; extractingan original spectral band Band 8 of the sentinel 2A to enhance other dark reflectivity ground objects; S2, based on the three extracted characteristic components, constructing a combined shadow indexto highlight a building shadow; and selecting an optimal threshold value by using an OTSU method to obtain a final urban building shadow distribution map. By the adoption of the technical scheme, thedifference between the shadow and other ground objects can be remarkably increased, the phenomenon that urban building shadow, water and dark reflectivity ground objects are mixed is effectively avoided, and the extraction precision of the urban building shadow is improved.

Description

technical field [0001] The present invention relates to the technical field of building shadow extraction, in particular to a building shadow extraction processing method for Sentinel 2A images. Background technique [0002] Shadow is a widely distributed feature in remote sensing images that cannot be ignored. In high-resolution images, urban building shadows are usually caused by tall buildings blocking light sources. The spectral information of the shadow area is greatly weakened, and its existence has caused great obstacles to the subsequent urban land use classification and change detection. Therefore, when using high-resolution remote sensing images to study urban problems, shadow detection is a step that must be considered in the image preprocessing process. [0003] At present, when using high-resolution remote sensing images for shadow detection, there are two commonly used methods, namely, the method based on the model and the method based on the nature of the sh...

AI Technical Summary

Problems solved by technology

However, the above building shadow extraction indexes are set for images with higher spatial resolution such as Quickbird and IKONOS, and are not suitable for the 10m resolution image of Sentinel 2A

In addition, the Sentinel 2A image has 13 bands, and the existing spectral index does not make use of its rich spectral information, so the extraction of the Sentinel 2A building shadow does not have a good effect

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