Geography Reference
In-Depth Information
Fig. 6.7 The classification of the major permanent, winter and summer irrigated crops within the
irrigation projects in the ERB for the data of LANDSAT-TM acquired in May and August 1987
''Why are the uncultivated areas again classified since the classification method
relies on the hierarchical approach using the mask-process, which separated the
uncultivated areas from the cultivated areas (including the fallow) in the previous
classification level?''
The answer, previously mentioned (see Chap. 5.7.1.2.1 ) , is that the hierarchical
approach of classification has its drawbacks that lead to mistakes in the results just
like any other approach. Accumulative errors result in those negatives brought by
production/extraction of the mask's layer either counting on results of supervised
or unsupervised classification, NDVI or others; or where, these credited approa-
ches cannot reach a degree of perfection in spectral separating of the Earth surface
features or the other classes of interest. This can also occur if these traditional
approaches of classification have the ability to reach a suitable rate in spectral
separation and classification. The hierarchical approach was not used in the
classification process or in the creation of the masks at each classification level as
it costs effort and time. As suggested in Fig. 5.35 , the classification process was
repeated on the classes which were not classified and completely extracted during
the last classification process. The use of this approach was to increase the clas-
sification accuracy (the final product that resulted from collecting outcomes of
each level and stage of the hierarchal classification), through a decreasing number
of features and classes which exist in the study area, either by eliminating some
Search WWH ::




Custom Search