Utilize este identificador para referenciar este registo: http://hdl.handle.net/10451/28185
Título: Accurate determination of surface reference data in digital photographs in ice-free surfaces of Maritime Antarctica
Autor: Pina, Pedro
Vieira, Gonçalo
Bandeira, Lourenço
Mora, Carla
Palavras-chave: Image analysis
Object-based classification
Ice-free surfaces
Polar regions
Data: 2016
Editora: Elsevier
Citação: Science of the Total Environment 573 (2016) 290–302
Resumo: The ice-free areas of Maritime Antarctica show complex mosaics of surface covers, with wide patches of diverse bare soils and rock, together with various vegetation communities dominated by lichens and mosses. The microscale variability is difficult to characterize and quantify, but is essential for ground-truthing and for defining classifiers for large areas using, for example high resolution satellite imagery, or even ultra-high resolution unmanned aerial vehicle (UAV) imagery. The main objective of this paper is to verify the ability and robustness of an automated approach to discriminate the variety of surface types in digital photographs acquired at ground level in ice-free regions of Maritime Antarctica. The proposed method is based on an object-based classification procedure built in two main steps: first, on the automated delineation of homogeneous regions (the objects) of the images through the watershed transform with adequate filtering to avoid an over-segmentation, and second, on labelling each identified object with a supervised decision classifier trained with samples of representative objects of ice-free surface types (bare rock, bare soil, moss and lichen formations). The method is evaluated with images acquired in summer campaigns in Fildes and Barton peninsulas (King George Island, South Shetlands). The best performances for the datasets of the two peninsulas are achieved with a SVM classifier with overall accuracies of about 92% and kappa values around 0.89. The excellent performances allow validating the adequacy of the approach for obtaining accurate surface reference data at the complete pixel scale (sub-metric) of current very high resolution (VHR) satellite images, instead of a common single point sampling.
Peer review: yes
URI: http://hdl.handle.net/10451/28185
DOI: 10.1016/j.scitotenv.2016.08.104
ISSN: 0048-9697
Aparece nas colecções:IGOT - Artigos em Revistas Internacionais

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