@InProceedings{MorelliFormEpip:1993:InGeVi,
author = "Morelli, Ademir Fernando and Formaggio, Antonio Roberto and
Epiphanio, Jos{\'e} Carlos Neves",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)}",
title = "Influ{\^e}ncia da geometria de visada na reflect{\^a}ncia
espectral de duas gram{\'{\i}}neas forrageiras",
booktitle = "Anais...",
year = "1993",
editor = "Cunha, Roberto Pereira da and Dias, Luiz Alberto Vieira",
pages = "80--95",
organization = "Simp{\'o}sio Brasileiro de Sensoriamento Remoto, 7. (SBSR).",
publisher = "Instituto Nacional de Pesquisas Espaciais (INPE)",
address = "S{\~a}o Jos{\'e} dos Campos",
keywords = "AGRONOMIA, REFLECTANCIA ESPECTRAL, REFLECTANCIA BIDIRECIONAL,
GEOMETRIA, RADIOMETRIA, RADIOMETRY, SPECTRAL REFLECTANCE,
BIDIRECTIONAL REFLECTANCE, GEOMETRY.",
abstract = "The objective of this research was to evaluate the influence's
variation of view geometry variation in spectral behavior of
herbaceous vegetation and soil underlying in composition pastures
for Brachiaria decumbens Stapf. cv. Basilisk Stapf and Brachiaria
brizantha Stapf cv. Marandu. The methodology development involved
the report analysis between the spectral reflectance and the
biophysics parameters of herbaceous vegetation and soil. For this
purpose radiometric and biophysics measurements were done for 25
vegetation samples and one soil sample, in experiment areas of
1000 m2, for each species. The multispectral bidirectional
reflectance measurements (500 to 1100 nm) were obtained in the
view zenith angles ({\'a}v) of 0¢X,15¢X,30¢X,45¢X and 60¢X for
three sectors of azimutal plain ({\"O}v = 0¢X,90¢X and 180¢X),
with the solar zenith angle variation controlled for an amplitude
of the 10¢X ({\'a}s = 45¢X to 55¢X) and the solar azimutal
variation compensated in the acquisition method. The following
vegetation parameters were measured: fresh and dry biomass, fresh
and dry green biomass, droughty biomass and leaf and stems; water
content of total, green and droughty biomass, Leaf Area Index
(LAI) and percentage of canopy cover. The soil parameters
available were color, roughness and chemistry composition. This
research intent is the comprehension of physical mechanisms
involved in the directional reflectance factor distribution of
complete homogeneous vegetation canopies and its influences in the
relation between spectral behavior and vegetation parameters. The
general scattering behavior was coherent with the dynamics
observed in the literature and was supported by two principal
phenomena: the {"}phase function{"} and {"}geometric effect 1{"}.
The major trends observed in the reflectance factor occurred in
the azimuth in the principal plane of the sun ({\"O}s = 0¢X and
180¢X), while the minor trends occurred in the azimuth direction
perpendicular to the principal plane of the sun ({\"O}v = 90¢X).
For all view angles and spectral bands the minimum reflectance
occurred near nadir ({\'a}v = 0¢X) and increased with increasing
view zenith angles for all azimuth directions. This trend is
caused by the shading of lower canopy layers, by components in the
upper layers and by viewing different proportions of the layer
components as the view angle changes ({"}effect 1{"}). In some
cases by an addictive effect of {"}phase function{"}, the
reflectance minimum was shifted slightly off-nadir in the forward
scattering direction ({\"O}s = 0¢X). This shift was maximized for
occurrence of reproductive structures in the top layers of cover,
because this structure is vertical and opaque. The near infra-red
band was less influenced by view geometry variation than in the
spectral bands of visible, because in the near infra-red band the
transmittance was nearly equal to the reflectance for most
structural components of herbaceous vegeta-tion, while in the
visible the reflectance is major, consequently the {"}effect 1{"}
is maximized. The major information content about vegetation cover
was obtained in the principal plane of the sun, in the
backscattering direction ({\"O}p = 180¢X), than showed better
relationships to the vegetation parameters, because of the
occurrence of {"}hot spot{"}. The vegetation parameters of
production and water content showed the best correlations, because
its parameters have more association to the near infra-red, that
exhibited the better perforf11ance than visible bands, more
associated to LAI and fresh and dry biomass components. The
{"}effect 1{"} was the dominant phenomenon with controlled the
directional reflectance distributions observed, but had its
effects alterated by the action of additional phenomenon {"}phase
function{"}.",
conference-location = "Curitiba, BR",
conference-year = "10-14 maio 1993",
copyholder = "SID/SCD",
isbn = "978-85-17-00054-6",
label = "6593",
language = "pt",
organisation = "Instituto Nacional de Pesquisas Espaciais",
ibi = "sid.inpe.br/iris@1912/2005/07.20.00.37.33",
url = "http://urlib.net/ibi/sid.inpe.br/iris@1912/2005/07.20.00.37.33",
targetfile = "080-095.pdf",
type = "Comportamento e Assinaturas de Alvos Naturais",
volume = "3",
urlaccessdate = "01 maio 2024"
}