CHAPTER 27
Consideration on Satellite Data Correction by Bidirectional
Reflectance Measurement of Coastal Sand with a Remote Sensing
Simulator
H. Okayama and J. Sun
ABSTRACT: In the field of remote sensing, there is a need to correct the intensities of
bidirectional reflectance because the satellite data collected in nadir and off nadir
directions show different values in spite of the measurement of the same point on the
Earth's surface. We measured the characteristics of bidirectional reflectance from
coastal sand using a remote sensing simulator. From the results of the measurements,
we obtained indicatrices, hence Minnaert constants (k's) were calculated. We corrected
the reflected intensity by assuming that the Minnaert constant (k) of the same area is
equal.
Introduction
In papers on reflection and scattering, Lambertian surfaces are usually assumed, but
natural surfaces are generally non-Lambertian and their spectral properties obtained
from remote sensing data from aircraft or satellite are dependent on view and sun
angles (Jackson et al., 1990; Royer et al., 1985; Slater and Jackson, 1982; Nicodemus,
1970). It is, therefore, necessary to take into account the bidirectional reflectance
distribution function (BRDF) of the target to compare quantitatively the measurements
acquired under different illumination and observation conditions. Knowledge of the
bidirectional properties of natural surfaces are especially important.
In the field of remote sensing there is a difference between the data in the
nadir and off-nadir directions for the observation of the same point on the Earth's
surface by side-angle imagery sensors such as the Advanced Very High Resolution
385
D.R. Green and S.D. King (eds.), Coastal and Marine Geo-Information Systems, 385–397.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
Consideration on Satellite Data Correction by Bidirectional
Reflectance Measurement of Coastal Sand with a Remote Sensing
Simulator
H. Okayama and J. Sun
ABSTRACT: In the field of remote sensing, there is a need to correct the intensities of
bidirectional reflectance because the satellite data collected in nadir and off nadir
directions show different values in spite of the measurement of the same point on the
Earth's surface. We measured the characteristics of bidirectional reflectance from
coastal sand using a remote sensing simulator. From the results of the measurements,
we obtained indicatrices, hence Minnaert constants (k's) were calculated. We corrected
the reflected intensity by assuming that the Minnaert constant (k) of the same area is
equal.
Introduction
In papers on reflection and scattering, Lambertian surfaces are usually assumed, but
natural surfaces are generally non-Lambertian and their spectral properties obtained
from remote sensing data from aircraft or satellite are dependent on view and sun
angles (Jackson et al., 1990; Royer et al., 1985; Slater and Jackson, 1982; Nicodemus,
1970). It is, therefore, necessary to take into account the bidirectional reflectance
distribution function (BRDF) of the target to compare quantitatively the measurements
acquired under different illumination and observation conditions. Knowledge of the
bidirectional properties of natural surfaces are especially important.
In the field of remote sensing there is a difference between the data in the
nadir and off-nadir directions for the observation of the same point on the Earth's
surface by side-angle imagery sensors such as the Advanced Very High Resolution
385
D.R. Green and S.D. King (eds.), Coastal and Marine Geo-Information Systems, 385–397.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.