Data/hora: 21/06/2024 10:39:54

Biblioteca(s): 	Embrapa Territorial.	
Data corrente: 	14/08/2020	
Data da última atualização: 	17/08/2020	
Autoria: 	MARTINS, V. S.; KALEITA, A. L.; GELDER, B. K.; SILVEIRA, H. L. F. da; ABE, C. A.	
Afiliação: 	VITOR S. MARTINS, IOWA STATE UNIVERSITY; AMY L. KALEITA, IOWA STATE UNIVERSITY; BRIAN K. GELDER, IOWA STATE UNIVERSITY; HILTON LUIS FERRAZ DA SILVEIRA, CNPM; CAMILA A. ABE, UNIVERSITY OF WISCONSIN-MADISON.	
Título: 	Exploring multiscale object-based convolutional neural network (multi-OCNN) for remote sensing image classification at high spatial resolution.	
Ano de publicação: 	2020	
Fonte/Imprenta: 	ISPRS Journal of Photogrammetry and Remote Sensing, v. 168, p. 56-73, oct. 2020.	
ISBN: 	0924-2716	
DOI: 	https://doi.org/10.1016/j.isprsjprs.2020.08.004	
Idioma: 	Inglês	
Conteúdo: 	Convolutional Neural Network (CNN) has been increasingly used for land cover mapping of remotely sensed imagery. However, large-area classification using traditional CNN is computationally expensive and produces coarse maps using a sliding window approach. To address this problem, object-based CNN (OCNN) becomes an alternative solution to improve classification performance. However, previous studies were mainly focused on urban areas or small scenes, and implementation of OCNN method is still needed for large-area classification over heterogeneous landscape. Additionally, the massive labeling of segmented objects requires a practical approach for less computation, including object analysis and multiple CNNs. This study presents a new multiscale OCNN (multi-OCNN) framework for large-scale land cover classification at 1-m resolution over 145,740 km2. Our approach consists of three main steps: (i) image segmentation, (ii) object analysis with skeleton-based algorithm, and (iii) application of multiple CNNs for final classification. Also, we developed a large benchmark dataset, called IowaNet, with 1 million labeled images and 10 classes. In our approach, multiscale CNNs were trained to capture the best contextual information during the semantic labeling of objects. Meanwhile, skeletonization algorithm provided morphological representation (?medial axis?) of objects to support the selection of convolutional locations for CNN predictions. In general, proposed multi-OCNN presented better classification accuracy (overall accuracy ~87.2%) compared to traditional patch-based CNN (81.6%) and fixed-input OCNN (82%). In addition, the results showed that this framework is 8.1 and 111.5 times faster than traditional pixel-wise CNN16 or CNN256, respectively. Multiple CNNs and object analysis have proved to be essential for accurate and fast classification. While multi-OCNN produced a high-level of spatial details in the land cover product, misclassification was observed for some classes, such as road versus buildings or shadow versus lake. Despite these minor drawbacks, our results also demonstrated the benefits of IowaNet training dataset in the model performance; overfitting process reduces as the number of samples increases. The limitations of multi-OCNN are partially explained by segmentation quality and limited number of spectral bands in the aerial data. With the advance of deep learning methods, this study supports the claim of multi-OCNN benefits for operational large-scale land cover product at 1-m resolution.	
Palavras-Chave: 	Aerial imagery; Convolutional neural network; Deep learning.	
Thesaurus Nal: 	Land cover.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Territorial (CNPM)	
Exemplares: 	CNPM - (5315-1) - UPC - AP - DD - 20/067 - AP - 2020.067 - DIS