Pl-6-4
numbers, maximum NDVI, minimum NDVI, digital
elevation data of the ground truth regions. Out of one
hundred clusters, 46 clusters can be directly assigned to
one of sixteen land cover classes. The rest of clusters are
assigned land cover classes using threshold values of
maximum NDVI, minimum NDVI or digital elevation
data. The threshold value of 0.15 for maximum NDVI is
used to discriminate “vegetation” and “non vegetation”.
The threshold value of 0.23 for minimum NDVI is used
to discriminate evergreen vegetation and the others. After
classification by decision tree method, there are some
unnatural patterns in classified image due to noises in
AVHRR or the effect of mosaicking to produce 10-days
composite AVHRR. To eliminate these undesirable
patterns, land cover classes of these portion were
substituted by the higher level land cover class in
hierarchical classification system.
8. CONCLUSION
By the method describing in the previous sections,
(1) Asia 30-second land cover data set and
(2) Asia 30-second ground truth data
were produced by the cooperation of the Land Cover
Working Group of the Asian Association on Remote
Sensing.
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