Analise Preliminar de Imagens TM Visando a Discriminacao de Cafe, Citrus e Cana-de-Acucar na Regiao de Furnas, MG.

Cafe, citrus e cana-de-acucar desempenham papel importante na economia, contribuindo na pauta dos produtos de exportacao. Furnas, localizada em Minas Gerais, tem sido caracterizada por um expressivo incremento em areas plantadas. Varios trabalhos tem sido realizados para discriminar e mapear a cana-de-acucar, utilizando dados orbitais, mas pouco tem sido feito para as culturas de cafe e citrus atraves de imagens de satelite. Neste trabalho foi utilizada analise digital de dados TM correspondentes a quatro bandas. A discriminacao espectral e a classificacao das culturas foram obtidas utilizando um algoritmo de maxima verossimilhanca implementado em um sistema interativo de analise de imagens. Sao apresentados dados de matrizes de classificacao, desempenhos medios e valores de reflectancia. Os resultados na area de estudo mostraram altos indices de discriminacao entre as culturas estudadas.Made available in DSpace on 2011-04-09T12:17:42Z (GMT). No. of bitstreams: 1 pab14set92.pdf: 271159 bytes, checksum: c893cdc166e810806e986131d037f731 (MD5) Previous issue date: 2001-09-12199

Origin of step-like and lobate seafloor features along the continental shelf off Rio de Janeiro State, Santos basin-Brazil

International audienceA combined analysis of seismic and morphological features identified in a set of high-resolution seismic reflection and bathymetric data, shows a systematic relationship between major modern seafloor morphological traces and the basinward migration of Late Pleistocene coastlines along the continental shelf of the Santos basin (Rio de Janeiro State, SE Brazil). Observed fairly continuous and sinuous mid-outer shelf escarpments are related to the sea-level variations and shelf exposure during the Last Glacial cycle. A bathymetric step at - 110 m is an erosional remnant of offlapping detached forced-regressive wedges that spread over 50 km in the shelf-dip direction, probably developed during periods of falling sea level between MIS 3 and 2. A second major escarpment at - 130 m was interpreted as the shoreline during the LGM, at the time of most extensive subaerial exposure of the continental shelf. However, a distal escarpment at - 150 m is expressed as a straight contour feature along the two main shelf-edge embayments that characterize the shelf break. This escarpment is coupled with a basal seaward-inclined and highly eroded ramp, and was interpreted as the erosional action of bottom currents during the last transgression due to the displacement of the southward flowing Brazil Current towards the present-day outer shelf. Previously published articles have regarded the morphological features observed on the modern shelf as indicators of stillstands during the post-LGM transgression. We conclude that, on the contrary, most of these features are actually from earlier parts of the Late Pleistocene and were formed in a regressive scenario under oscillating and relative slow sea-level fall

Análise espectral e temporal da cultura do café em imagens Landsat Spectral and temporal behavior analysis of coffee crop in Landsat images

A definição da resposta espectral da cultura do café é uma das etapas na identificação de lavouras cafeeiras em imagens de satélites de sensoriamento remoto, para fins de mapeamento e estimativa de área plantada. O objetivo deste trabalho foi avaliar o potencial das imagens adquiridas pelos satélites da série Landsat, no mapeamento da cultura do café para a previsão de safras. Foi feita uma análise temporal do comportamento espectral de lavouras de café-formação e café-produção por meio de imagens livres de nuvens adquiridas nos anos de 1999 e 2001. Também foi analisado o comportamento espectral das classes pastagem e mata, que compõem os alvos de maior ocupação na área de estudo. As imagens do período seco foram mais eficientes no mapeamento de lavouras de café-formação e café-produção. As imagens da banda 4 dos dois sensores apresentaram melhor diferenciação espectral entre café e os demais alvos da cena. A reflectância do café-produção apresentou grande variabilidade entre lavouras, que pode ser atribuída à idade, espaçamento de plantas, cultivar, indicando a necessidade de trabalho em campo para a correta identificação das lavouras de café nas imagens Landsat.<br>The definition of the spectral response of coffee crop is one of the steps to identify coffee fields in remote sensing images in order to map and estimate planted area. The objective of this work was to analyze the potential of the images acquired by the Landsat series satellites, for coffee crop mapping and forecast. A temporal analysis of the spectral behavior of coffee crop fields under development and under active production was performed through cloud free images acquired in the years of 1999 and 2001. The spectral behavior of pasture and forest was also analyzed due to their relevance in the study area. The results showed that images acquired during the dry season were more efficient to map coffee crop at early development and under production. Band 4 (near infrared) of both sensors (TM and ETM+) presented best performance for spectral differentiation between coffee crop and other scene targets. The analysis of the reflectance values for active producing coffee crop showed a high spectral variability which may be attributed to age, plants spacing, cultivar, indicating a need for field work for the identification of coffee crop in Landsat scenes