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Figure 1. Study area in this research. The area is located in the Kansai district of Japan. It covers 10 km horizontally by 10 km
vertically. Five cities and one ward are mainly included in this area.
Land use
Parcel level
Land cover
Local area level
e^ S
4
Q individual Dimension
Figure 2. Concept of the decision tree method developed
in this study.
observation of the data was 5 degrees. Atmospheric
correction based on MODTRAN was carried out so that
NDVI was derived from the reflectance data. Before the
calculation of vegetation cover ratio, reflectance data were
resampled with a spatial resolution of 10 m/pixel.
2.2.2 Land Use Map: We applied Detailed Digital
Information (10 m grid land use) of Kinki area to the
analysis as land use data. The categories of these land use
data contain industrial area, residential area, commercial area,
road, public space, forest/grassland, agricultural land, and
park/green zone.
2.3 Methods
2.3.1 Concept of the decision tree method: Figure 2 shows
the concept of the decision tree method developed in this
study. The method is composed of two viewpoints: parcel
level and local area level. In general, it is required to
investigate the conditions of vegetation cover considering land
use because the greenery planning depends on their land-use
categories. At the parcel level, theses comparisons are carried
out as parcel scale evaluations. In addition, the viewpoint of
local scale is necessary for the vegetation-covered areas. It
is notice that the lineation of the vegetation-covered areas with
some cores of greenery plays an important role in the
conservation of ecosystem. Therefore, this method contains the
relative evaluation of individual dimension of the current
489
vegetation-covered area (CVA) in a local area. It is clarified
the relative role of the CVA in the conservation of greenery in
the local area at the local area level.
2.3.2 Calculation of Vegetation-covered Area: We applied
the practical estimation method based on the assumption that
the radiance of a mixel was represented by linear
combination of the radiance of its components ( Hirano, et
al. 2002) . This estimation method is described with Equation
(1) as
a NDVI+b
c NDVI+d (1)
= V; + NIR;
= Vs - NIR;
= V; - Vp + NIR;- NIR,
V; - Vo - NIR; * NIR,
where
GS S S
a is vegetation cover ratio in percent, V reflectance in the
visible band, NIR reflectance in the near-infrared band, v and
s mean vegetation-covered area and vegetation-uncovered
area, respectively. Through conforming the land-cover
categories to the land-use categories, we decided the
reflectance values of Vs, NIRs, Vo, and NIR» of each
land-cover category using the land use data.
Then, the areas, where the vegetation cover ratio were more
than 50 96, were defined as vegetation-covered areas ( VA).
On the other hand, regardless of vegetation cover ratio, the
areas, where land-use categories were agricultural land, were
defined as VA.
2.3.3 Calculation of the Local Vegetation Cover Ratio: For
investigating local status of greenery, we calculated a local
vegetation cover ratio (LVR) with window process, each
500 m by 500 m in size. The VA were applied to this
calculation. We compared the LVR with the standard value,
15%, established as the one of the objectives for greening by
the local government, Osaka prefecture.
2.3.4 Calculation of Dimension per Vegetation-covered
Area: Practically, to examine the LVR is not sufficient for
evaluating the local greenery. The role of a
