Data sets are described either raster form or vector e 
form.(depending on data items.) 
A cell is a closed area of the earth surface divided at 30 
seconds interval in longitude and latitude respectively from the 
point of zero degree of east/west longitude and the equator. In e 
raster format, the characteristics of a cell is taken from those of 
the center of each cell, which is the smallest unit to represent 
data. 
Attributes in vector form are divided in two classes; 
mandate and optional. 
Metadata which describe data itself should be attached. 
4.2. Layers and Selection of features 
Following six items are prescribed for development 
4.3. 
Drainage system. Divided into lakes and rivers. Lakes 
are represented in polygon form, and rivers are represented in 
line form. As Global Map data, both main rivers and main 
lakes are described. 
Transportation. Divided in general roads, highways and 
railways. Each layers are shown in line. In the layer of general 
roads, main roads are selected in the Global Map. The layer of 
highways is specified as roads whose speed limit exceeds that 
of general roads and for only automobiles. 
Administrative boundary. Administrative boundary up to 
second level within a country are described as polygons. 
Land Use 
Land Use is classified using satellite images with high resolution, 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
e Elevation. Unit is meter, described in raster form. and is mainly done by visual interpretation. 
® Vegetation. Described in raster form. Classifications are In this land use layer, classification category has hyerarchy structure 
shown below. as shown below. 
e Land use. Described in raster form. Classifications are 
shown below. 
Land Use 
| | 
Land |  DrainageWater | | Ocean | 
Non-Vegetated Area Vegetated Area 
| | 
Built-up Area | | Barren Area | Non-Forest | Forest | 
| | | 
| Agricultural Area | | Grassland/Shrub |. | Wetland | Mixture | 
  
Figure 3 The specification of Land Use 
4.4. 
Vegetation 
Fifteen categories shown in Table 1 are prescribed in the 
specifications. 
4.5. Attributes of Vector-type layers 
Attributes shown in Table 2 are prescribed for each vector 
layer in the specifications. 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
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