Influência da geometria de iluminação e do ângulo de visada na resposta espectral da cultura do feijão (Phaseolus vulgaris L.) / Radiation geometry and viewing angle influence on the spectral response of bean crop (Phaseolus vulgaris L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The study of the spectral behavior of crops, through field radiometry, contributes to a better precision in models generated by remote sensing, when they are used to estimate and analyze crops’ agronomic variables. Once sensors aboard of satellites are able to acquire images under different viewing angles and at different times of the day, it is necessary to understand the effect of such variables on the crops’ spectral response. The objective of this research was to evaluate the influence of the viewing angles (0º, 30º and 45º) and three radiometric acquisition times (10:00 a.m, 12:00 a.m and 2:00 p.m), related to different sun elevation angles, on the spectral behavior of bean crop, as well as on the relationship between Leaf Area Index (LAI) and Normalized Difference Vegetation Index (NDVI). The experiment was installed in the “Fazenda Areão”, of the ESALQ/USP, in Piracicaba, SP, from March to June, 2005. The experimental design was the randomized blocks, with split plots, with three blocks, three primary treatments (acquisition times) and three secundary treatments (viewing angles). Nine field campaigns were carried out with the SPECTRON SE-590 spectroradiometer. Bands TM3 e TM4 were simulated from the determined reflectance factors and, with these bands, vegetation indices were generated. According to the results, it was concluded that the variation on acquisition time did not lead to a significant variation on the reflectance factors in the TM3 and TM4 bands. On the other hand, the variation in the viewing angle significantly affected (p≤0,05) the reflectance factor in the TM3 and TM4 bands, for every day of measurement. Regarding the relationships between LAI and NDVI, the linear model showed the best fit (p≤0,05).

ASSUNTO(S)

sensoriamento remoto spectroradiometry spectral behavior região espectral feijão remote sensing radiometria

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