ques caused some gaps and
to reduce this gap and
orphology was applied as
5 circle structuring element
the 5x5 circle Structuring
istortion and gaps up to 5
selection results in the loss
27).
y closing applied image
application, despite the
image, one more filter was
minate gray value of noise
only zero gray values and
els (Figure 8).
g noise gray values.
orithm (Bayram, B., 2008)
growing algorithm using
algorithm application
inary image generated by
s converted to vector data
FigurelO. Automated extorted coastline converted to vector
data.
5. RESULTS
Since coastal management requires rapid, up-to-date, and
correct information, coastal movements have primary
importance for coastal managers. Remote sensing is an
important technique for detecting and monitoring coastlines
using satellite images. In the literature most of the algorithms
developed for optical images have been discussed in detail. In
this study the use of SAR images was investigated for automatic
coastline detection by using PALSAR images.
The algorithm was applied on 4 images gathered in 2007 and
2010 in two polarizations as HH and HV. In order to test the
accuracy of coastline detection, all images were digitized
manually. To calculate the total difference between the
automatic coastline detection and manually digitizing, land side
of the each image was converted to a closed polygon and its
area was calculated. Then the calculated areas of manual and
automatic extractions were compared Table 2. Since digitizing
coastline from PALSAR images is not an easy and simple task
due to the feature of SAR images, for each pair the manual
digitizing which was thought to be the best coastline extraction
was chosen.
Automatic Manual
Image Digitalized(pixel) | Digitalized (pixel)
2007 HV 315504
2007 HH 315804 pes
2010 HV 316805
2010 HH 316887 316360
Table 2. Comparison between automatic coastline detection and
manual digitizing.
Overall length of the coastline extracted automatically was
compered with the manually digitized coastline (Table 3).For
each image scene the difference is less than %0.9.
Manual Automatic Automatic
Image Digitalized | Digitalized Digitalized
8 (pixel) (pixel) (Percent)
2007 HV 24716 0,61
2007 HH 24506 24355 0,85
2010 HV 24898 0,41
omy om 25055 021
Table 3. Comparison between the lengths of automatically
extracted and manually digitized coastlines.
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