Eficácia de medidas de similaridade para a classificação de séries temporais associadas ao comportamento fenológico de plantas

Orientadores: Luiz Camolesi Júnior, Ricardo da Silva TorresDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de TecnologiaResumo: Fenologia é o estudo de fenômenos naturais periódicos e sua relação com o clima. Nos últimos anos, tem se apresentado relevante como o indicador mais simples e confiável dos efeitos das mudanças climáticas em plantas e animais. É nesse contexto que se destaca o e-phenology, um projeto multidisciplinar envolvendo pesquisas na área de computação e fenologia. Suas principais características são: o uso de novas tecnologias de monitoramento ambiental, o fornecimento de modelos, métodos e algoritmos para apoiar o gerenciamento, a integração e a análise remota de dados de fenologia, além da criação de um protocolo para um programa de monitoramento de fenologia. Do ponto de vista da computação, as pesquisas científicas buscam modelos, ferramentas e técnicas baseadas em processamento de imagem, extraindo e indexando características de imagens associadas a diferentes tipos de vegetação, além de se concentrar no gerenciamento e mineração de dados e no processamento de séries temporais. Diante desse cenário, esse trabalho especificamente, tem como objetivo investigar a eficácia de medidas de similaridade para a classificação de séries temporais sobre fenômenos fenológicos caracterizados por vetores de características extraídos de imagens de vegetação. Os cálculos foram realizados considerando regiões de imagens de vegetação e foram considerados diferentes critérios de avaliação: espécies de planta, hora do dia e canais de cor. Os resultados obtidos oferecem algumas possibilidades de análise, porém na visão geral, a medida de distância Edit Distance with Real Penalty (ERP) apresentou o índice de acerto mais alto com 29,90%. Adicionalmente, resultados obtidos mostram que as primeiras horas do dia e no final da tarde, provavelmente devido à luminosidade, apresentam os índices de acerto mais altos para todas as visões de análiseAbstract: Phenology is the study of periodic natural phenomena and their relationship to climate. In recent years, it has gained importance as the more simple and reliable indicator of effects of climate changes on plants and animals. In this context, we emphasizes the e-phenology, a multidisciplinary research project in computer science and phenology. Its main characteristics are: The use of new technologies for environmental monitoring, providing models, methods and algorithms to support management, integration and remote analysis of data on phenology, and the creation a protocol for a program to monitoring phenology. From the computer science point of view, the e-phenology project has been dedicated to creating models, tools and techniques based on image processing algorithms, extracting and indexing image features associated with different types of vegetation, and implementing data mining algorithms for processing time series. This project has as main goal to investigate the effectiveness of similarity measures for the classification of time series associated with phenological phenomena characterized by feature vectors extracted from images. Conducted experiments considered different regions containing individuals of different species and considering different criteria such as: plant species, time of day and color channels. Obtained results show that the Edit Distance with Real Penalty (ERP) distance measure yields the highest accuracy. Additionally, the analyzes show that in the early morning and late afternoon, probably due to light conditions, it can be observed the highest accuracy rates for all views analysisMestradoTecnologia e InovaçãoMestre em Tecnologi

Descriptor Correlation Analysis for Remote Sensing Image Multi-Scale Classification

International audienceThis paper addresses the problem of remote sensing image multi-scale classification by: (i) showing that us- ing multiple scales does improve classification results, but not all scales have the same importance; (ii) show- ing that image descriptors do not offer the same contri- bution at all scales, as commonly thought, and some of them are very correlated; (iii) introducing a simple ap- proach to automatically select segmentation scales, de- scriptors, and classifiers based on correlation and ac- curacy analysis

Classifier Selection Based On The Correlation Of Diversity Measures: When Fewer Is More

The ever-growing access to high-resolution images has prompted the development of region-based classification methods for remote sensing images. However, in agricultural applications, the recognition of specific regions is still a challenge as there could be many different spectral patterns in a same studied area. In this context, depending on the features used, different learning methods can be used to create complementary classifiers. Many researchers have developed solutions based on the use of machine learning techniques to address these problems. Examples of successful initiatives are those dedicated to the development of learning techniques for data fusion or Multiple Classifier Systems (MCS). In MCS, diversity becomes an essential factor for their success. Different works have been using diversity measures to select appropriate high-performance classifiers, but the challenge of finding the optimal number of classifiers for a target task has not been properly addressed yet. In general, the proposed solutions rely on the a priori use of ad hoc strategies for selecting classifiers, followed by the evaluation of their effectiveness results during training. Searching by the optimal number of classifiers, however, makes the selection process more expensive. In this paper, we address this issue by proposing a novel strategy for selecting classifiers to be combined based on the correlation of different diversity measures. Diversity measures are used to rank pairs of classifiers and the agreement among ranked lists guides the classifier selection process. A fusion framework has been used in our experiments targeted to the classification of coffee crops in remote sensing images. 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