International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
different satellite image classification methods. For this
purpose, landuse classification of the study area was conducted
by different supervised image classification procedures and the
results were compared with one another. © Landsat 7 ETM+
satellite image acquised in 11.16.2001 and the IDRISI
Klimanjaro image processing and the GIS package were used in
this study. There are different image processing and GIS
softwares using all around the world. A lot of them have the
similar properties and capabilities for use remote sensing
purposes. The IDRISI Klimanjaro image processing and the
GIS package is one of the most useful and economic software
of these image processing packages.
In this study, the Idrisi Klimanjaro was used for the different
image classification chosen; Parellelpiped, Maximum
Likelihood, Minimum Distance to Means and Fisher Classifier
(Linear Discriminant Analysis) classifiers were used to
determine which classifier is more effective and useful for this
study purpose. To test these classifiers, a land use application
was made in the study area. In this context, CORINE method
was used for land use classification. 7 land classes were
selected. Artifical Surfaces (Urban Areas), Agricultural Areas,
Forests and Olive Trees, Wetlands and Water bodies (sea, lake)
are the selected land classes according to CORINE land use
method (CORINE, 1995). Bare Land class was added to the
selected classes. For this purpose, PCA (Principal Component
Analysis) composite image which was composed by PC2, PC4
and PC5 band combination was constituted because the each
PC images reflects the most principle components on that band.
Training sites have been digitized on screen and so a signature
file to clasify the image have been made. After then, four image
classifiers, Parellelpiped, Minimum Distance, Maximum
Likelihood and Fisher, were applied to clasify the composite
image respectively.
2. METHODOLOGY.
There is a consistent logic to all of the supervised classification
routines in almost all image processing softwares, especially in
IDRISI Klimanjaro, regardless of whether they are hard or soft
classifiers (IDRISI Klimanjaro Guide, 2004). In addition, there
is a basic sequence of operations that must be followed no
matter which of the supervised classifiers is used. In this study
the following sequence of operations were used.
1. Defining of the Training Sites.
2. Extraction of Signatures
3. Classification of the Image.
2.1 Defining of the Training Sites
The first step in undertaking a supervised classification is to
define the areas that will be used as training sites for each land
cover class. This is usually done by using the on-screen
digitized features. For this purpose, band is chosen with strong
contrast (such as a near infrared band) or a color composite
image for use in digitizing. In this study, a color composite
image which was made with PC2, PC4 and PC5 images was
used. Generally, one should aim to digitize enough pixels so
that there are 10 times as many pixel for each training class as
there are bands in the image to classify. This should be made
with at least two or three training sites but, the more training
site is selected, the better results can be gained. However, this
procedure assures both the accuracy of classification and the
true interpretation of the results. In this context, each land class
have been represented with two and three training sites.
2.2 Extracting of Signatures
After the training site areas have been digitized, the next step is
to create statistical characterizations of each information. These
are called signatures in Idrisi (Idrisi Klimanjaro Guide, 2004).
With this module, categorization of infomation which of each
pixels is possible. In this step, the goal is to create a signal
(SIG) file for every informational class.The SIG files contain a
variety of information about the land cover classes they
describe. Each SIG file also has a corresponding SPF file that
contains the actual pixel values used to create the SIG file. It is
used only by HISTO histogram (HISTO) in displaying
histograms of signatures). These include the names of the
image bands from which the statistical characterization was
taken, the minimum and mean values on cach band, and the full
variance /covariance matrix associated with that multispectral
image band set for that class (IDRISI Klimanjaro Guide,2003).
1092
Inter
2,3 (
The
This
desci
The
peda
landi
the N
there
MINI
used
stand
that i.
The 1
there
trainii
classe
24G
In thi
used |
classif
minim
are use
The |
classif
of the
data (R
Whilst
simple
is tha
parelle
classfie
maxim
unless {
prior p
account
Finally,
parellel
(Richar
The Mi
This cla
each bai