i) capability to overlay user's data on other registered data 
j) options of data accessibility: single use, group use, open 
public distribution 
3. USER TYPES 
The developed system has five types of users as listed below. 
Super user, server managers, group leaders, and registered users 
are in the hierarchical structure, and the upper one has a right to 
approve the direct lower one. Registered users can download 
the data in the system and upload his/her own data to the system, 
while unregistered users (general public) can see the data in the 
system. 
(a) Super user 
- manages a total system and a main server 
- has right to approve ‘system manager” 
(b) System managers 
- manage a local server 
- have right to approve ‘group leader’ 
(c) Group leaders 
- have right to approve 'general registered users' 
(d) Registered users 
- have right to upload/download data 
(e) Unregistered users 
- can see the data and overlay his/her own data on them 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Super user 
[: | | 
SM SM SM SM 
| | | 
GL GL GL 
| 
| | | | 
RU RU RU RU 
  
  
  
  
  
  
  
  
  
SM: System manager 
GL: Group leader 
RU: Registered user 
D: Database 
Figure 2 Structure of CEReS Gaia users 
4. USEFULNESS OF THE SYSTEM 
Registered users can use the developed system, CEReS Gaia, 
for the following ways. 
- hare his/her data only within a user group such as a 
working group 
- distribute his/her data to the public 
- analyse his/her data by overlaying with other data in the 
system 
- . publish his/her geo-registered research output 
- . accumulate geo-registered research outputs by an academic 
society 
192 
- . check his/her land cover training/validation data with other 
data in the system 
5. DISCUSSION 
The first step of data sharing is to publish the produced data. 
For example, in the case of global land cover mapping, if all 
mapping projects shares their land cover training data, we will 
have enough number of training data for the next mapping 
attempt. Generally, the first action to share the data is to publish 
the data. Actually, many research organizations publish their 
produced data. Why do we need to collect these published data? 
The reason is the efficiency of data analysis. If we download 
each data we need from different distributors, it takes much time. 
The recommended way is to see and analyse multiple data in 
one portal site. 
There have been developed many geospatial web-based 
databases for data sharing. Among them, some portal sites such 
as Harvard Geospatial Library are well developed with user- 
friendly interface. However no single portal site can cover all 
user's needs in different fields. In the future, it is recommended 
to link existing portal sites each other because each portal sites 
has specific advantage. 
The developed portal site has unique advantages in efficient 
overlay function, data sharing in a limited group members, and 
the international server expansion. 
6. CONCLUTION 
A new geospatial data sharing/overlay system, CEReS Gaia, has 
developed as a tool of research and education of land 
environmental science. Among other existing geospatial data 
sharing portal sites, the developed system has features of data 
sharing capability within a specific user group and a capability 
to expand many servers worldwide. Any researcher who is 
interested in using CEReS Gaia actively as a “system manager” 
or “group leader” can contact the authors. 
References 
Giri, C., Hastings, D., Reed, B. and Tateishi, R., 2009. Status 
and Future of Global Databases. Chapter 9, Manual of 
Geographic Information Systems, ASPRS, pp.113-139, 
Tateishi, R. and D. Hastings (Ed.), 2000. Global Environmental 
Databases, ISPRS WG IV/6 (1996-2000), Geocarto 
International, 250p. 
Tateishi, R. and D. Hastings (Ed.), 2002. Global Environmental 
Databases vol.2, ISPRS WG IV/8 (2000-2004), Geocarto 
International, 154p. 
website 1: GCMD 
http://gemd.nasa.gov/ (access 15 Apr. 2011) 
website 2: GEO portal 
http://Www.geoportal.org/ (access 15 Apr. 2011) 
website 3: Harvard Geospatial Library, 
http://calvert.hul.harvard.edu:8080/opengeoportal/ (access 
15 Apr. 2011) 
Acknowledgements 
This work was supported by Japan Society for the Promotion of 
Science (JSPS) research grant, KAKENHI(2222001 1). 
Mee SA pl Reb us FX uud A. 
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