International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
b. Spatial feature
Spatial features are the shape, size and the edge of
the target.
c. Texture feature
Textures provide important characteristics for the
analysis of many types of images including natural
sensing data and biomedical modalities.
In this study, we mainly used the NDVI and TC
feature images, these feature images and the
preprocessed TM image were input into the C5.0
classification platform together.
3) Extract samples and create sample database
A sufficient number of training samples and their
representativeness are critical for image classifications
(Hubert-Moy etal.2001, Chen and Stow 2002,
Landgrebe 2003, Mather 2004). Training samples are
usually collected from fieldwork, or from fine spatial
resolution aerial photographs and satellite images. To
grantee the precise of the training samples, we did
some fieldwork. The information of the sample area
is:
Location: southeast coast of Australia
Latitude and longitude: 33°03'00"~34°47'00"S,
149°23'00"~152°01'00"E
Climate: wet climate
Ecoregions: Southeast Australia temperate forests,
and Eastern Australian temperate forests
Some of the training samples were collected from
the LANDSAT TM images. This process can
implement on remote sensing or GIS softwares. The
features displaying on the image are inflected by
many factors, such as climate, terrain. According to
ecoregions and months, the 18 scenes images were
dm
LeftiMLC result)
middle(classified image) right{C5.0 result)
divided into three teams. We chose three or four
scenes images to select samples, and guaranteed every
scene's sample points were no less than 500 points.
4) The creation of the classification rules
When we have sufficient training samples and
good feature files, the next procedure is to get
classification rules. Here, the C5.0 classification
platform can be adopted. According to the grouping of
the above procedure this study can get three decision
rules.
5) Classification
The last procedure is to use the decision rule to
classify. In the study, every scene of the 18 scenes
images of Victoria used one of three rules to
implement classification. When every scene image
was classified, the classification results were
mosaiced, and then we got the classification result of
Victoria.
3 EXPERIMENTAL RESULTS AND
ACCURACY ASSESSMENT
3.1 Experimental Results
Maximum likelihood classifiers are frequently
available and widely used for land cover classification
from multispectral imagery. In the study MLC
classification was also used to classify the images of
Victoria. Also, the same training data was used to
classify one scene by using C5.0 classification method
and MLC.
WE unelaisified
Bl cropland
Bl forest
Li graxs
| shrub
water
wetland
Figure 4. Some comparisons of MLC result and C5.0 result
Figure 4 shows some visual comparisons of MLC
result and C5.0 result, we can easily found that the
C5.0 result is closer to the actual classified image.
Figure 5 shows the classification result of Victoria.