Shadows: photo-interpretive criteria for remote sensor images in the compartmentalization of the physical environment

Abstract

Satellite images, because they are records of targets with different spectral behavior and spatial arrangements, present textural variations. Topography gives a shadowed effect, causing a reduction in the reflectance values in the shadowed areas. This textural variation, often complex, can be an interesting tool in the compartmentalization of relief. Thus, the main objective of this study is to evaluate and utilize these shadows as a photo-interpretive criteria in the separation of compartments of land in orbital images, in the municipalities of Peruíbe and Itanhaém, located on the southern coast of the state of São Paulo. The techniques employed included utilization of a binary image of the shadowed and the illuminated areas, in association with a digital elevation model and the original image itself to aid in the photo-interpretation, conducted according to conventional criteria. The results point to the viability of applying the conventional model of photo-interpretation together with the application of shadow analysis criteria, with satisfactory and innovative results for the process of land compartmentalization. Key words: Remote Sensing. Photointerpretation. Texture analysis. Shadows. Compartimentalization of land.