emergency. Both of them are one-way data collection and 
updating, how to unify both organically in together, promote 
each other, this paper is to solve the problem. In VGI platform, 
the user to provide data, at the same time, they also data users, 
so some scholars proposed the concept of produser (Coleman 
and Georgiadou et al., 2009). In this paper the user can be 
called closing points. In the two levels of understanding, firstly, 
in data update participants of the ring, mainly there are two 
participants, one is from VGI platform public data provider, the 
other is professional surveying and mapping departments, both 
focusing on different aspects and with different purposes to take 
data update work in turn; In data flow, data comes from VGI 
platform acquisition, through a variety of process eventually 
went back to VGI platform. In this mechanism, we can think of 
the data is not a pool of stagnant water, but the flow of the 
source of living water. Both of them complete each other, VGI 
focus on the change of the data, in the contrast, SDI focus on 
validation and heavy acquisition. The changes found by VGI 
can promote SDI to schedule the update plans, meanwhile, SDI 
release new data to VGI platform which can promote amateurs 
to provide real-time data more actively. But there are also some 
problems, such as the users of VGI may only pay attention to 
and update the region who are living or be believed more 
interesting, and other remote areas of the update working may 
need professional departments to complete, and SDI department 
may not carry out the validation work timely and effectively, 
which will affect the data update and flow. 
4. APPLICATION 
In this section, this paper takes one professional surveying and 
mapping department in china as an example, connecting with 
data updating workflow and requirements, discusses the 
proposed mechanism for the possible application prospect and 
problems. Firstly , in China VGI data source is less than other 
countries in the world, there are many reasons, such as the 
public do not contribute data actively and data privacy. For 
example, Openstreetmap in China has scarce data, only in 
metropolises such as Beijing and Shanghai can get high quality 
data. Secondly, in the aspect of the professional surveying and 
mapping departments actual update situation in China, although 
at present many cities in china have been built the fundamental 
geographic information system, but the data update situation is 
not optimistic, the update mechanism lacks of systematic 
planning, which is difficult to ensure that the data not out of 
time. In the basic geographic data update mode, a lot of local 
professional surveying and mapping departments according to 
certain update period update complete coverage of the database, 
which is very easy to cause the inconsistency between various 
database versions. The linkages between fundamental 
geographic database and application database are not 
established, which cause the problem that lack of the updating 
linkage between databases. For example, municipal departments 
had built a new road, when surveying and mapping departments 
go to field surveying and mapping, the change information 
could be found. There is no updating channel for departments of 
surveying and mapping to the application departments, which 
increase the cost of time and energy. The traditional version 
update mode directly influences the efficiency updating of 
electronic map, which cause the update frequency of electronic 
map on the market at present also can only do the important city 
update 2 times a year, provincial capital city and general cities 
updated 1 time a year, as many as billions of POI data accuracy 
is difficult to guarantee. 
Based on the above situation, this paper tried to design a 
mechanism of surveying and mapping in accordance with 
China's situation, which can be described as followed: 
  
  
Figure 4.The updating flow 
5. CONCLUSION 
This paper gives a mechanism form VGI to SDI, explores the 
possibility of VGI as complement to detect changes and provide 
more details information for SDI, in turn, form SDI to VGI. The 
mechanism or cycle includes collecting VGI data, preprocessing 
data, matching the homonymous elements between VGI and 
SDI vector data, detecting changes, verifying the credibility of 
the changes, updating SDI database, updating the products to 
end-users. The paper discusses the method of data collection 
and preprocessing, the matching algorithms of homonymous 
elements , the detection of change and the definition of change 
types, the confirmation and publication for SDI and the ring fo 
updating. Then, taking one professional department in china as 
example, connecting with data updating workflow and 
requirements, the paper discusses the proposed mechanism for 
the possible application prospect and problems. 
6. REFERENCES: 
Coleman, D. J. and P. Eng, 2010. Volunteered Geographic 
Information in Spatial Data Infrastructure: An Early Look At 
Opportnities And Constraints, GSDI. 
Coleman, D. J. and Y. Georgiadou, et al, 2009. Volunteered 
Geographic Information: the nature and motivation of produsers. 
International Journal of Spatial Data Infrastructures Research 
4 (2009) , pp. 332-358. 
Coleman, D. and B. Sabone, et al, 2010. Volunteering 
geographic information to authoritative databases: Linking 
contributor motivations to program characteristics. Geomatica 
64, pp.27-40. 
Goodchild, M. F, 2007. Citizens as sensors: the world of 
volunteered geography. GeoJournal 69 (4) , pp.21 1-221. 
Mooney, P. and P. Corcoran, 2011. Can Volunteered 
Geographic Information Be a Participant in eEnvironment and 
SDI? Environmental Software Systems. Frameworks of 
eEnvironment 359, pp.115-122. 
Saalfeld, A, 1988. Conflation Automated map compilation. 
International Journal of Geographical Information System 2 
(3), pp.217-228. 
Zook, M. and M. Graham, et al, 2010. Volunteered geographic 
information and crowdsourcing disaster relief: a case study of 
the Haitian earthquake. World Medical & Health Policy 2 (2) 
pp. 7. 
7. ACKNOWLEDGEMENTS 
This paper is supported by the following projects, including 
Fudamental Research Funds for the Central Universities(No.21 
4275597) and the Key Technology and Application of Location 
Based Sensor Network and Holo Information Map 
(2012BAH35B03). 
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