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CONSTRUCTION OF GROUND REFLECTANCE MAP FROM REMOTE SENSING
DATA AND ITS APPLICATION TO TEMPORAL DATA ANALYSIS
T.Kusaka, Y.Kawata, H. Okazaki and S.Ueno
Kanazawa Institute of Technology, P.O. Kanazawa-South,
Nonoichimachi, Ishikawa 921 , JAPAN
ABSTRACT
In the present study we describe a method to estimate the
optical thickness of the atmospheric haze from a Landsat
data set itself. Then we give a conversion method from the
original CCT level data to the true ground albedo data with
an aid of the Atmospheric Effect Correction System developed
at Kanazawa Institute of Technology. We also show that the
signature extension becomes possible by correcting the
original Landsat data for the atmospheric effects and this
approach will be a powerful tool in temporal data analysis.
Finally, a processing system implementing the signature
extension system is described. We introduce a new and
powerful table look-up method in classification and a data
base containing the statistical information on albedos for
various ground classes with time.
INTRODUCTION
It has been known that the contrast of the surface images
obtained by the Landsat's MSS is frequently degraded by
atmospheric haze. This atmospheric haze causes a significant
decrease in classification accuracy. In the temporal
analysis of one particular geographyical location it is very
unfortunate that we can not compare a Landsat data set
quantitatively with another Landsat data set taken at
different time ( because of different haze conditions). If
the optical thickness of haze is known, the true spectral
response by ground, namely the ground albedo, can be
computed from the observed data set. This problem has been
studied by Odell and Weinman (Odell 1975 ) and more
intensively by us (Kawata 1978;Haba 1979). It is not always
possible to get the optical thickness of the haze by direct
measurement . In addition to the foregoing discussion,
it is imperative to increase performance in data processing
as the remote sensing of the Eath surface becomes
operational and the volume of data increases. These are
major motivations by which we began to work on the present
study.
Here we first describe a method to estimate the value
of the optical thickness of the haze from the remotely
sensed data itself. Then we convert a relative CCT level
data set into a absolute ground albedo data set using the
Atmospheric Effect Correction System. Finally , we give a
signature extension system consisting of the data base phase
and table look-up phase.