site, and the rule-based classification was carried out by using
the spatial information and the texture information. In addition,
the new classified image was created through the connection by
extracting the house plantation in each result of the supervised
classification and the result of the rule-based classification. The
result of rule-based classification method was masked by the
mask band created using the result of supervised classification
method.
Each classified image deciphered the classification degree by
comparing the visual interpretation results based on the specific
areas such as the vegetation area, downtown area etc. In
addition, the accuracy was analyzed by comparing between the
house plantation area and visual interpretation area of the
classification results.
Selection of study site
= m
sje acquis
1 processing
| |
Supervised Rule-based
classification classification
Comparison by
classification method |.
“Efficient classification
Efficient icem
Figure 2. Flow Chart
3. ANALYSIS OF IMAGE CLASSIFICATION
AND RESULT
For the vinyl greenhouse detection, two copies of Formosat-2
image photographed in March, 20th, April, 8th and 15th 2008
for including all Jeju areas were obtained, and it was treated as
mosaic. The mosaic image was divided for including Seogwipo
area as the study area, and the vinyl greenhouse was extracted
through the image classification.
3.1 Image Classification
(1) Supervised classification
If the user knows the information about the subjects, then the
supervised classification method to acquire information about
the unknown region based on the information must be effective.
For the image classification by the supervised classification, the
classification item was set by the sea, vegetation, buildings and
bare soil, vinyl greenhouse, and the image classification was
carried out by using the parallel-piped classification, minimum
distance classification, maximum likelihood classification,
Maharanobis distance classification.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B1, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
Characteristic Symbol Class
The Sea Sea | blue
: Forest sea green
Vegetation
Grass green
Buildings Building E | cyan
Bare Soil Soil yellow
Vinyl 1 red
Vinyl greenhouse Vinyl 2 | magenta
Vinyl 3 I maroon
Table 1. Class of Image Classification
(2) Rule-based classification
The vinyl greenhouse was extracted by using the object-based,
rule-based classification. The rule-based classification added
the rule to create the rule about attribution for dividing the
subjects such as the spatial information and spectral information
etc. and to clearly distinguish the subjects (Biao et al., 2007).
This study defined the rule to extract the vinyl greenhouse as
follows.
» NDVI value is lower than the value of vegetation.
» Form is akin to a rectangle.
» The form is no longer than the road.
» [thas the constant area range.
Based on the rule above, the range of the attribute value which
can classify the attribution of the vinyl greenhouse most was
designated. The designation about the range of the attribute
value is based on the user's decision, so the best value should be
selected through the various attempts.
(3) Visual interpretation
In order to be used as the comparison materials for the
accuracy analysis of the image classification results, the vinyl
greenhouse was extracted through the visual interpretation.
3.2 RESULT ANALYSIS
(1) Detection results by the classification method
The results by each classification method were divided with
the vegetation area, downtown area, so the misclassification
degree and the features were examined.
The image classification results of the parallel-piped
classification of the supervised classification method were not
good so it was excluded from the subjects of examination.
In the vegetation area with only the vegetation and vinyl
greenhouse, the classification of the vinyl greenhouse was
carried out in the classification method used in the study. But in
the rule-based classification, the minority of the objects of the
vinyl greenhouse was not extracted. In the downtown area, the
misclassification was found from all classification method to
take part in. The building with the similar vinyl greenhouse and
spectral information was misclassified with the vinyl
greenhouse in the supervised classification method, and
Maharanobis distance classification showed the best results. In
the case of the rule-based classification, the vegetation, bare
soil, building with the similar form of the object, vegetation
index and the size with the vinyl greenhouse was misclassified
as the vinyl greenhouse. Fig. 3 showed the classification results
in the downtown area.
clas
out
witl
the
ob
mis
clas
witl
by.
in e
gre
rest
bas
Thi
As
ove
the
pro
bui
inf
thre
par
ren
wh
me
sho
are