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5, GROUND TRUTH DATA BASE 
Ground truth data are applied to design and select the 
sensor system of remote sensing and to decide the best season 
and time for acquisition of remote sensing data. The ground 
truth data are also used to analize and interpret the remote 
sensing data. In this section, the establishment of the 
ground truth data base system are described. By using the 
data base system , the operator can easily pick up some pieces 
of physical informations such as spectral reflectance, polari- 
zation and sun-illumination etc. for his application. 
5-1. OUTLINE OF GROUND TRUTH DATA BASE SYSTEM 
This data base system has three subsystems, a data base 
creation and correction subsystem, a looking up subsystems, 
a display subsystem. Under these subsystems, a spectral 
data file, a spectral index glossary file, thesaurus file 
are maintained and utilized for an application. 
The data base creation and correction subsystem creates 
the index and glossary from the spectral data file or 
creates and corrects the anotation data and so on. 
The looking up subsystem firstly anolyzes the reference 
entry language and seeks for the reguired data file. 
The display subsystem shows the referenced data to a 
graphic display as the operator can easily understand what 
it says. 
The spectral data fioe contains the spectral curve of 
the objects, where spectral curves are read from a microfilm 
or with the cordinates style and recorded on a microfilm or 
on a disk storage. 
The spectral index glossary file contains the index 
of each spectram or the glossary of the symbols used for 
the index with the disk storage. 
The thesaurus file is the dictionary for a synonyms 
terms. 
5-2. DATA BASE CONSTRACTION 
The constraction of the data base has the following 
requests: each of terms should not be related simply, should 
not be in a simple tree model, should be easily added or 
corrected. And the data base should be easily referenced 
by the users who don't have experienced a computor before, 
and should be easily used near the place where the analysis 
is carried out through the terminals. 
5-3. PATTERN INDEX 
The spectral characteristics of the objects are given with 
the continuous or the discrete curve according to the way of 
feasurements. If we try to store this curve to the disk 
storege, it is required a large space and it is impossible 
sometimes. Here we used K-L transform conversion for one 
dimensional spectral pattern to extract the distinctive 
feature from the curve.