Spectral Difference in the Image Domain for Large Neighborhoods, a GEOBIA Pre-Processing Step for High Resolution Imagery

Abstract

Abstract:Contrast plays an important role in the visual interpretation of imagery. To mimic visual interpretation and using contrast in a Geographic Object Based Image Analysis (GEOBIA) environment, it is useful to consider an analysis for single pixel objects. This should be done before applying homogeneity criteria in the aggregation of pixels for the construction of meaningful image objects. The habit or "best practice" to start GEOBIA with pixel aggregation into homogeneous objects should come with the awareness that feature attributes for single pixels are at risk of becoming less accessible for further analysis. Single pixel contrast with image convolution on close neighborhoods is a standard technique, also applied in edge detection. This study elaborates on the analysis of close as well as much larger neighborhoods inside the GEOBIA domain. The applied calculations are limited to the first segmentation step for single pixel objects in order to produce additional feature attributes for objects of interest to be generated in further aggregation processes. The equation presented functions at a level that is considered an intermediary product in the sequential processing of imagery. The procedure requires intensive processor and memory capacity. The resulting feature attributes highlight not only contrasting pixels (edges) but also contrasting areas of local pixel groups. The suggested approach can be extended and becomes useful in classifying artificial areas at national scales using high resolution satellite mosaics.

Geotecnologias Aplicadas À Avaliação De Taxas De Impermeabilização Da Terra Em Ambiente Urbano

“…Fonte: Elaborado pelos autores, 2020 O que difere esse método dos demais é a formação de objetos atribuídos à imagem conforme a escala trabalhada. Há, portanto a transformação da imagem em conjunto de objetos formados pela segmentação, e posteriormente agregados conforme a escala de regionalização, também chamada de merge (DE KOK, 2012). Para Hay e Castillo ( 2008) o GEOBIA foi o termo mais apropriado para aplicação em Geociências, pois os objetos estudados possuem o atributo geoespacial central, além de possibilitar a integração com conceitos geográficos e ecológicos quanto à diferenciação dos espaços.…”

Testing Texture of VHR Panchromatic Data as a Feature of Land Cover Classification

“…Kit et al (2012) used VHR satellite images to identify informal settlements. De Kok (2012) proposed the simulation of a large 49 × 49 Laplacian filter for testing neighbourhood contrast in order to enhance the detection of artificial areas. Esch et al (2010) provide examples of urban classification based on the analysis of the texture of synthetic aperture radar (SAR) images.…”