International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
accuracy. Kappa statistics and its variance were also calculated
to test the significance of difference in accuracy. The
significance of difference test between the confusion matrices
was done using the Z test with a — 0.05.
In addition to the quantitative assessment, a qualitative
assessment of the classified images was done by examining the
classified maps visually and relating it to field knowledge. This
is to find out if the map reflects reality.
4. RESULTS AND DISCUSSIONS
The ML classification was performed using different numbers
of input classes and two different image resolutions 30 and 15
meters.
4.1 ML Results Using Landsat 30 m Resolution Data
The ML classification of the original data was performed using
different numbers of input classes. The first classification was
done using six input classes (i.e. NLP, F1, F2, F3, F4 and NF).
In the second classification no distinction was made between
the forest classes, thus the input was NLP, F and NF. The third
classification used only two classes, NLP and Other. The
classification output was then compared to find out which
number of input classes gave the highest class accuracy for
NLP. The best classification output in terms of NLP class
accuracy was selected for comparison with the SP classification
output.
Figure 5 presents the classification result using six input
classes. The total detected NLP covers 3,946 ha of RKL1 which
accounts for approximately 58.48% of the total area. The map
shows a large amount of NLP detections along the main road in
the upper right part of the image. The lower left part shows less
NLP detections compared to the upper right part. Notice the
road and the agriculture area in the upper left corner of the
image. Figure 6 shows the same image in which the forest
classes and the non forest classes were merged after
classification.
Maximum Likelihood Classification
Output
(30m resolution)
Legend
Figure 5. Classified map of the original image using ML
Classifier (6 classes)
Figure 7 presents the classification output using 3 input classes.
This map shows less NLP detections compared to the first
classification output. Again most of the NLP detections are
found along the main road and smaller amount in the lower left
part of the image. The total NLP detections amount to 2,193 ha
of RKLI, approximately 32.5% of the area. This is less then the
area found in the first classification.
Maximum Likelihood Classification d
Output "
(30m resolution)
Legend
Wl New logged point
[J Other
Figure 6. NLP Detection Map derived from the 6 classes ML
output map.
The result of the third classification shows much more NLP
detections compared to the previous classifications. The total
area covered by NLP is 5,362 ha which corresponds to 79.46%
of the total RKL1 area. Observe the detection of the road and
agriculture area in the left part of the image.
Maximum Likelihood Classification
Output
(30m resolution)
Legend
New logged point
EB Forest
[J Non forest
0 = 4 km
Figure 7. Classified map of the original image using ML
Classifier (3 classes
4.2 ML Results Using Landsat 15 m resolution data
Figure 8 shows the output of the classification of the improved
image. In general, the same trend in distribution of NLP
detections can be observed as for the original image. However,
the image shows a more distinct pattern. The area covered by
NLP is 1,624 ha, which is about 24.07% of the total RKL I area.
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