Navegando por Assunto "Processamento digital de imagens"

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Acesso aberto (Open Access)
Avaliação e aplicação de dados de sensores remotos no estudo de ambientes costeiros tropicais úmidos, Bragança, norte do Brasil
(Universidade Federal do Pará, 2000-11-17) SOUZA FILHO, Pedro Walfir Martins e; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429
The study site is situated in the Cretaceous Bragança-Viseu coastal basin. The holocenic evolution of this area is marked by muddy progradation over a submerging coast, where is developed one of the most mangrove system of the world, with almost 6,000 km2. This research has showed that orbital remote sensing data can provide excellent geologic and coastal land use information. The SAR RADARSAT-1 imageries represent a powerful tool to understand the coastal processes in the wet tropical environments, mainly in the mangrove coasts. This fact is related to microwave radiation can be interpreted for Amazon coastal zone mapping and monitoring, because SAR image constitutes in the unique source of data with all-weather remote sensing capability, in response to difficulty to get optical images in the Amazon, due to all-time cloud cover. Landsat TM imageries are excellent data sources to integration with RADARSAT-1. They present a good performance in coastal environments discrimination. The remote sensing data integration allow a synoptic view of the area and provide geobotanic (relation between coastal environment and vegetation) and multitemporal information. In addition to integrated data, geographic information system (GIS) combines different data sets and simultaneously interprets the spatial and temporal relationship between various coastal environments. This way, GIS allows for a more comprehensive, accurate and easier interpretation of a geomorphologic mapping under an organizational philosophy to control data towards use the information to coastal zone management. The application of remote sensing data in the tropical coastal studies was used in different approaches. In relation to spatial and temporal variability of the shoreline, this study has revealed that during the Holocene, the coastal plain is marked by a muddy progradation. However, from the analysis of the remote sensing images were possible investigate the shoreline variability under long (1972-1998) and short (1985-1988, 1988-1990, 1990-1991) term, which is characterized by shoreline retreat, probably due to climatic changes, such as El-Niño and La-Niña events. These climatic events control the rainfall along the coastal zone, where severe erosional period (1985- 1988) are coupled with high precipitation rate (> 4,000 mm/yr.). From the point of view of the spatial analysis of the coastal changes, the mangroves constitutes one of the most environments to be analyzed by remote sensing images, as in the electro-optical spectrum due to their high reflectance in the infrared, as in the microwave due to their rough surface responsible for high backscattering. Therefore, mangroves have showed to be an excellent geologic indicator to detect and to quantify short and long-term morphological coastal changes. To conclude, remote sensing data integration, GIS and auxiliary fieldwork data present a fundamental role to the integrated coastal zone management, environmental risk assessment, local characterization of the study sites, base maps upgrading and information dissemination for public consultation, which are all significant factors in this decision-making process.
Acesso aberto (Open Access)
Dinâmica da cobertura florestal a partir de análises realizadas em áreas de extração seletiva de madeira no Estado do Pará
(Universidade Federal do Pará, 2023-09-29) ROCHA, Nívia Cristina Vieira; GALBRAITH, David; http://lattes.cnpq.br/2145475131329843; ADAMI, Marcos; http://lattes.cnpq.br/7484071887086439; https://orcid.org/0000-0003-4247-4477
The selective logging in the Amazon region is an activity that holds relevance in social, economic, and environmental aspects. In many cases, this is considered a low environmental impact activity in the forests when compared to deforestation. This research assessed canopy opening in selectively logged areas in Eastern Amazon over different years with reduced impact. Detailed monitoring was conducted in these areas using both hemispherical images and orbital images to evaluate the persistence of impacts over time. Hemispherical photographs were used to measure canopy opening and provide a high-resolution assessment of the logged areas. This study also utilized images obtained from Landsat, Sentinel, and Planet satellites. Spectral Mixture Analysis and enhancement techniques were applied to these orbital images to detect canopy opening impacts caused by selective logging. Hemispherical images revealed that even 17 years after the logging activities ceased, the impacts caused by selective logging were still discernible. Meanwhile, orbital images allowed for the identification of logging at different time intervals depending on their respective resolutions. From the results, this study highlights the importance of the combined use of hemispherical and satellite images to monitor the effects of selective logging over time in the Amazon. This enables a more comprehensive understanding of forest dynamics, the persistence of impacts, and the importance of continuous monitoring in logged areas to assess long-term effects and adopt sustainable management strategies.