In other words, an AWLC meta-database changes closed 
knowledge of land use and land cover to open or 
common knowledge for general researchers. This 
common knowledge is a common property of general 
researchers and it promotes the understanding of the 
environment of Asia. 
4.2 Classification of Agricultural Land 
Agricultural land is the most important class in land use 
planning. However this is one of the most difficult class 
to extract from continental scale satellite data because of 
small unit area and various crop calendars. One of the 
solutions is the use of new sensor with the middle 
resolution(50-200 m) and frequent observations(1-3 days). 
Also, SAR data has a possibility to be applied to the 
classification of agricultural land. 
4.3 Others 
There are several other subjects to do for the better 
global/continental land cover monitoring, 
- Digitization of historical land cover maps 
Since globally covered satellite image exists only from 
1981, historical land cover information is required for 
long term land cover change analysis. 
- Application of SAR data 
Cloud coverage is the main barrier to hinder the 
production of cloud free multi temporal data. The use of 
SAR data gives new possibility for land cover 
monitoring. However basic research of cfessification 
using SAR data is required. 
- Development of better digital global base map 
The Digital Chart of the World(DCW) is the most 
frequently used digital global base map. However the 
accuracy is about 500 meters in both longitude and 
latitude direction(Tateishi 1998). Therefore when we use 
global/continental satellite image with a resolution better 
than 1 km(AVHRR), a better global base map will be 
required. 
- Representation of land cover by continuous variables 
like vegetation cover percentage 
Conventional category type representation of land cover 
has some limitaMon in its ability to describe various 
types of land covers. The representation of land cover by 
continuous variables such as vegetation cover percentage 
or vegetation height is recommended to use jointly with 
category type representation. 
5. CONCLUSIONS 
494 
Global/continental scale land cover monitoring is 
important as the input to environmental studies and also 
large scale land use planning. Authors developed land 
cover data sets in global area and Asia. Also they listed 
up future necessary studies for global/continental land 
cover monitoring. 
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