Suchergebnisse

O objetivo deste artigo é fornecer informação sobre a detecção em tempo real da área desflorestada (DETER - Detecção em Tempo Real do Desflorestamento na Amazônia Brasileira) utilizando imagens do MODIS de alta resolução temporal. O DETER é parte do projeto operacional que estima a taxa anual do desflorestamento na Amazônia Brasileira (PRODES - Projeto de Monitoramento do Desflorestamento na Amazônia). Um método para detecção rápida do desflorestamento foi delineado para dar suporte à fiscalização do uso da terra na região. A fim de avaliar o método proposto foi selecionada uma área teste que cobre uma cena do Landsat ETM+ (227/68) localizada no Estado do Mato Grosso. Para este propósito uma série multitemporal de imagens refletância de superfície do MODIS (MOD09) e de imagens ETM+ correspondentes ao período de junho a outubro de 2002 foi analisada. Foi verificado que pequenas áreas de desflorestamento (menores do que 15 ha) foram detectadas pelas imagens MODIS com menor acurácia quando comparado com as imagens do ETM+. À medida que as áreas desflorestadas aumentam os resultados do MODIS e do ETM+ tendem a convergir. Este procedimento mostrou ser adequado para detectar e monitorar operacionalmente as áreas desflorestadas e vem sendo utilizado pelo governo desde 2004 como parte do Plano de Ação para a Prevenção e Controle do Desmatamento na Amazônia Brasileira. ; The objective of this paper is to provide near real time information about deforestation detection (DETER) in the entire Brazilian Amazon using MODIS high temporal resolution images. It is part of the operational deforestation monitoring project to estimate the annual deforestation rate in the Brazilian Amazon (PRODES). A rapid deforestation detection method was designed to support land use policies in this region. In order to evaluate the proposed method a test site was selected covering a Landsat ETM+ scene (227/68) located in Mato Grosso State. For this purpose a multitemporal series of MODIS surface reflectance images (MOD09) and the corresponding ETM+ images from June to October 2002 were analyzed. It was found that small deforested areas (lower than 15 ha) were detected by MODIS images with lower accuracy when compared with ETM+ images. As the deforested areas increase MODIS and ETM+ results tend to converge. This procedure showed to be adequate to operationally detect and monitor deforested areas and has been used since 2004 as part of a government plan to control the Amazon deforestation. ; The objective of this paper is to provide near real time information about deforestation detection (DETER) in the entire Brazilian Amazon using MODIS high temporal resolution images. It is part of the operational deforestation monitoring project to estimate the annual deforestation rate in the Brazilian Amazon (PRODES). A rapid deforestation detection method was designed to support land use policies in this region. In order to evaluate the proposed method a test site was selected covering a Landsat ETM+ scene (227/68) located in Mato Grosso State. For this purpose a multitemporal series of MODIS surface reflectance images (MOD09) and the corresponding ETM+ images from June to October 2002 were analyzed. It was found that small deforested areas (lower than 15 ha) were detected by MODIS images with lower accuracy when compared with ETM+ images. As the deforested areas increase MODIS and ETM+ results tend to converge. This procedure showed to be adequate to operationally detect and monitor deforested areas and has been used since 2004 as part of a government plan to control the Amazon deforestation.