Caracterização espectral de plantios de Eucalyptus utilizando dados Hyperion EO-1 e SRTMSpectral characterization of Eucalyptus plantation using Hyperion EO-1 and SRTM data

A disponibilidade de dados hiperespectrais trouxe expectativas nos meios acadêmicos e empresariais quanto à potencialidade de sua aplicação no setor florestal. O objetivo deste trabalho foi avaliar a aplicação de dados hiperespectrais do sensor Hyperion EO-1 na caracterização espectral de plantios de Eucalyptus spp. e os efeitos da geometria de iluminação nesse processo. Para avaliar a geometria de iluminação foram utilizados dados topográficos provenientes do SRTM (Shuttle Radar Topography Mission) e as condições de iluminação presentes no momento da aquisição da imagem de satélite, gerando assim um fator de iluminação para a área de estudo. Os dados hiperespectrais foram convertidos para valores de FR de superfície, os quais passaram a constituir os dados fundamentais de todo o trabalho. A área de estudo contemplou os plantios do gênero Eucalyptus spp., pertencentes à empresa Fibria S.A., localizados no município de Capão Bonito (SP). Foram coletados dados de diferentes espécies e em diferentes etapas de desenvolvimento, o que caracteriza diferenças estruturais nos dosséis dos plantios. As componentes principais foram aplicadas nos dados e foram confeccionados gráficos dos fatores referentes às duas primeiras componentes, dos quais foram extraídas informações estruturais sobre os plantios. AbstractThe availability of the hyperspectral data brought expectations in academic and business circles regarding the potential of its application in the forestry sector. The goal of this work was to evaluate the implementation of hyperspectral data of the Hyperion EO-1 sensor in spectral characterization of the Eucalyptus spp. plantations and the effects of illumination geometry in this process. To assess the illumination geometry, topographical data were used from the SRTM (Shuttle Radar Topography Mission) and illumination conditions present at the time of the acquisition of satellite image, thereby a factor of illumination for the study area. Hyperspectral data were converted to values of surface bidirectional reflectance factor BRF, which become the fundamental data of all the work. The study included the plantations of the genus Eucalyptus spp., belonging to the company Fibria S.A., located in the Capão Bonito city, state of São Paulo. Data were collected from different species and in different stages of development, indicating structural differences in the plantations canopy. The principals components have been applied to the data and graphics were made of factors relateding to the first two components were made, and they were extracted provided structural information about the species studied

CONVERSÃO DE NÚMEROS DIGITAIS DE IMAGENS ORBITAIS EM VALORES DE FRB DE SUPERFÍCIE

TM/Landsat 5 images from four different dates have been converted to surface Bidirectional Reflectance Factors (BRF surface) through two alternatives. The first one has included the 6S atmospheric correction code and the second one has been based on the radiometric normalization of the TM/Landsat 5 images. Radiometric data from a pasture during the Landsat 5 flight over the study area (one specific date) were compared to the BRF surface determined from the two conversion alternatives. Results have indicated that the spectral characterizations of different targets, independent from the conversion alternative, would be consistent, mainly for targets no so dark as water, for instance. The spectral characterization carried out by BRF surface values calculated by the 6S code presented higher consistency. The statistical comparison between the BRF surface from the field and those determined by the two alternatives has indicated higher similarity between BRF surface from the pasture and those originated from the 6S code application.Imagens TM/Landsat 5 de quatro diferentes datas tiveram seus números digitais (ND) convertidos para Fatores de Reflectância Bidirecional de superfície (FRB de superfície) mediante a aplicação de duas diferentes alternativas. A primeira incluiu a aplicação do modelo de correção atmosférica 6S e a segunda a normalização radiométrica aplicada sobre a série temporal de imagens. Dados radiométricos coletados sobre uma área de pastagem concomitantemente a uma das passagens do satélite Landsat 5 foram utilizados na comparação entre os FRB de superfície gerados a partir das duas alternativas de conversão mencionadas. Os resultados indicaram que as caracterizações espectrais de objetos realizadas a partir dos valores de FRB de superfície, determinados através das duas alternativas, seriam consistentes, principalmente para objetos não escuros como a água. Nesse aspecto, as caracterizações espectrais realizadas com valores de FRB de superfície calculados a partir do modelo 6S apresentam ligeira maior consistência. A comparação estatística entre os FRB de superfície de campo com aqueles convertidos pelas duas alternativas indicou maior similaridade entre os dados de campo e aqueles oriundos do modelo 6S

IMPACT OF TOPOGRAPHIC CORRECTION ON SOIL AND VEGETATION COVER SPECTRAL CHARACTERIZATION BY TM/LANDSAT 5 IMAGERY

Several topographic correction methods have been developed to be applied to orbital imagery. The main objective of these initiatives has been focused on improving land cover mapping. Despite of some discussions that include spectral approaches, no attention has been given to the impact of such correction on the spectral characterization of different targets. That impact can influence relationships commonly explored between radiometric data from orbital imagery and biophysical and/or geophysical parameters. TM/Landsat 5 images (orbit 218, row 76) from a mountainous region located between São Paulo, Minas Gerais and Rio de Janeiro states (Brazil) were converted to surface reflectance values. Two topographic correction methods considering different sampling strategies were applied. The local illumination was taking into account during the result analysis in order to evaluate the selective effect of the topographic correction on the spectral characterization of bare soils and vegetated surfaces. The results indicated that the sampling strategy influences both the visual aspect of the topographic corrected images and the spectral characterization of targets. Spectral distortions caused by the topographic correction procedures were higher at darker illumination conditions. The topographic correction is a procedure that deserves attention when exploring spectral characterization of different targets. Sometimes it contributes positively in qualitative approaches such as mapping or digital classification, but it can imply in severe influence on quantitative approaches that are dependent on the targets spectral characterization

Dados TM/LANDSAT na identificação do ataque da Vespa-da-Madeira em plantios de Pinus sp

Landsat/TM images (TM3 TM4, TM5 and TM7 spectral bands) from areas covered by Pinus sp. (pinus) stands, sub-tropical forests and grasslands, were selected considering four dates related to the outbreaks of a woodwasp (Sirex noctilio, Fabricius). The selected dates were: 03/27/88, 08/08/90, 06/10/92 and 07/15/93. In 1988 the woodwasp has not been detected in these pinus stands. During the year of 1990, it killed an average 10% of trees. In 1992 and 1993, the outbreaks were reduced to an average of 1% of killed trees, due the application of silvicultural procedures, including timely selective thinning for sustained vigour. All images were matched considering that of 1988 as a reference. Then, they were transformed in reflectance images. Atmospheric correction method was applied in order to reduce the atmospheric influence in the reflectance values. Vegetation index images were made by the ratio between TM4 and TM3 bands images. Multitemporal vegetation indexes were compared with the woodwasp outbreaks and selective thinning data. Meteorologic data were also considered in that comparison. Visual analysis was carried out, using color compositions that have been made by TM3, TM4, TM5 and TM7 bands combinations, trying to identify patterns that could be related to the woodwasp outbreaks. The results showed that the outbreaks and the selective thinning were not detected through both visual analysis and vegetation indexes evaluation.Pages: 557-56

A fisionomia da cobertura vegetal do Parque Nacional do Pantanal Matogrossense (PNPM) identificada através do sensor TM/Landsat: uma análise multitemporal

Pages: 670-67

APLICAÇÃO DO MODELO SAIL NO ESTUDO DE REFLECTÂNCIA ESPECTRAL DE DOSSÉIS DE MUDAS DE Eucalyptus sp. E DE Aspidosperma sp

Por razões técnicas o resumo deste artigo não está disponível. Para maiores informações baixar arquivo completo

Pre-Launch Absolute Calibration of CCD/CBERS-2B Sensor

Pre-launch absolute calibration coefficients for the CCD/CBERS-2B sensor have been calculated from radiometric measurements performed in a satellite integration and test hall in the Chinese Academy of Space Technology (CAST) headquarters, located in Beijing, China. An illuminated integrating sphere was positioned in the test hall facilities to allow the CCD/CBERS-2B imagery of the entire sphere aperture. Calibration images were recorded and a relative calibration procedure adopted exclusively in Brazil was applied to equalize the detectors responses. Averages of digital numbers (DN) from these images were determined and correlated to their respective radiance levels in order to calculate the absolute calibration coefficients. It has been the first time these pre-launch absolute calibration coefficients have been calculated considering the Brazilian image processing criteria. Now it will be possible to compare them to those that will be calculated from vicarious calibration campaigns. This comparison will permit the CCD/CBERS-2B monitoring and the frequently data updating to the user community

Caracterização espectral de estágios sucessionais de vegetação secundária arbórea em Altamira (PA), através de dados orbitais Spectral characterization of successional stages of vegetation in Altamira (PA), Brazil using orbital radiometric data

Imagens TM/Landsat 5 (bandas TM1-TM5 e TM7) de Altamira, PA, de 07.02.1991 foram transformadas em reflectância de superfície usando o modelo 6S de correção atmosférica com o objetivo de caracterizar espectralmente formações florestais secundárias. Dados biofísicos (DAP, G e H) foram coletados de 16 parcelas em campo, os quais foram utilizados no cálculo da área basal total (GT) e da rugosidade do dossel (Rug) e no estabelecimento de correlações entre os valores de reflectância de superfície dessas mesmas parcelas. Os coeficientes de correlação mais elevados foram verificados nas relações com a banda TM7. Regressões lineares foram estabelecidas tendo como variável dependente os parâmetros biofísicos e como variável independente, os valores de reflectância de superfície da banda TM7, a partir das quais foram elaborados mapas temáticos representativos da distribuição espacial dos parâmetros biofísicos. A reflectância de superfície não foi sensível a valores pequenos de dados biofísicos. Apesar disso, a metodologia aqui empregada mostrou-se eficaz para estimativas remotas de dados dendrométricos.Landsat 5 TM images (TM1 to TM5 and TM7 spectral bands) from Altamira PA (Brazil) for 02.07.1991, were transformed into surface reflectance images by the 6S atmospheric correction code in order to characterize spectrally secondary succession stages of vegetation. Biophysical data (ADBH, ABA, TBA, THS and THSTD) collected in the field from 16 sampled vegetation plots were utilized in a correlation study between them and the surface reflectance values extracted from the orbital images. The highest correlation coefficients were found for the TM7 spectral band. Linear regression models were determined for each biophysical parameter considered and thematic images representing the spatial distribution of these parameters were made. The spectral data were not sensitive for detecting lower biophysical parameter values. Nevertheless, the results show that there was a good match between that spatial distribution and the study area landscape, indicating that these thematic images could be utilized in preliminary evaluations of the vegetation's biophysical characteristics

Análise multivariada de dados dendrométricos e radiométricos referentes à uma plantação de Pinus

In remote sensing studies, it is a common procedure to relate information acquired from orbital images to those obtained from laboratory or field works. To analyze how both of these two types of information are related, the statistical analysis is the most indicated technique, mainly considering scatterplots, regression models and correlation coefficients. Researches involving vegetation are the most frequently carried out and this type of approach is very usual to understand how spectral data are related to canopy parameter. For a given set of forest parameter, the multivariate statistical analysis is applied to show the potential of this tool for both providing a model and supporting an adequate data interpretation.Pages: 1641-164