International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
LE ES 75 Vans Lie PocorieChess facto) Clan Dbsendar
08 bands
; | Red Edge & Near Inf. 2
Figure 7: NDVI from the area under study.
At Figure 7 one perceives that the classifications with the eight
WorldView-II bands and with the Red Edge and Near Infrared
2 bands improve the discrimination of targets, if comparing to
the use of only bands red, green, blue and infrared common at
other high spatial resolution systems or only using the red and
near infrared bands, considered at the conventional NDVI
calculation.
The quality improvement of classifications using WorldView-II
data was quantified by the calculation of the Kappa indices of
classification, according to Table 1.
TABLE 1: Kappa indices of classifications.
Classification Kappa (k) index
4 bands 0.6481
8 bands 0.8927
Red and Near infrared 1 0.3478
Red Edge and Near infrared 2 0.8471
According to the Kappa indices, the worst classifications are
those using only bands Red and Near infrared (0.3478) as well
as the four traditional bands (0.6481). The low performance of
these classes can be due to the similar spectral response of
vegetation types at these bands and to the improved
performance of classifications with eight bands (0.8927) and
with channels Red Edge and Near infrared 2 (0.8471).
The classification with Red Edge and Near infrared 2, although
it presents a lower performance when compared with the 8
bands classification, is computationally much more faster,
specially when large areas are mapped, taking into account
that high resolution images demand much memory and
processing capacity.
164
The use of attributes of the new WorldView-II spectral bands
were implemented at the software package InterIMAGE,
allowing the classification of large areas. The performance of
bands Coastal and Yellow was highest for the discrimination of
classes Tidal channels and Bare soils respectively. Band
Yellow is also helpful for the identification of paleodunes.
After the analysis from the most robust attributes at the
exploratory analysis, including the texture attributes
implemented at InterIMAGE vl. 27, the scene classification
was performed. In comparison to other classifications the
results were improved due to the availability of the new bands
Yellow and Red Edge, eliminating frequent confusions such as
e.g. among Ceramic Roofs and Bare soil.
Another important aspect to be emphasized is the classification
of tidal channels, which was facilitated by decision rules
modeled at InterIMAGE, using attributes of band Coastal, and
the classification of the Beach area, based on attributes from
band Yellow, which was also important to characterize those
areas with paleo-dunes and dunes (Figure 08).
Tidal chanel
Blockhouses
Mangroves
Ceramic roof
Metal roof Bare soil
Figure 8: Land Cover Map
CONCLUSION
The objective of this study was to analyze the performance of
the new spectral bands from WorldView-II satellite to map
important features of a coastal urban area in Maranháo State,
emphasizing the possibilities of dircrimination for different
types of vegetation.
It is concluded that the new bands available at WorldView-II
sensor system, specially Red Edge, present the highest capacity
for discrimination among Mangrove and Semi-evergreen
Tropical Forests. The combination of spatial and spectral
resolutions allows the improvement of separation among the
physical characteristcs of targets to be mapped, resulting in
higher detail and precision of land cover maps.
The
Geo
clas:
algo
sepa
of |
avai
Cove
Mar
very
Ref
BLA
aval
Sao
BÜC
E 2
anal
CON
Kin;
COS
OLI
Kno
the
dew
AN,
Inte:
and
Unr
DIG
Ban
http
Ban
DIG
Wo
201!
spac
EHI
Sist
a re
Ren
mét
ed..
GE(
by
http
201
GEI
SEC
REC
aglo
