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International Archives of the Photogrammetry, Remote Sensin 
g and Spatial Information Sciences, Volume XXXIX-B4, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
For instance, national multi scale geo-spatial databases ranged 
from 1: 4 million to 1:50000 have been established in China, 
and regional multi scale geo-spatial database varied from scale 
1:10000 to 1:1000 have also been established in most provincial 
regions. However, due to the rapid economic construction and 
society development, geo-spatial features such as rivers, roads, 
resident buildings often change, so current geo-spatial databases 
become older and older, and become difficult to be applied in 
the all kinds of applications. More and more users intensively 
require geo-spatial data providers to keep geo-spatial database 
up to date. 
In order to provide up to date geo-spatial data, many countries 
have started national plans of geo-spatial database updating. 
United States of America has made a large plan of national 
mapping plan and promised to keep the geo-spatial data update 
every 7-10 days. In China, the updating project of National 
Fundamental Geographical System 1:50000 database started in 
2006. In this project, the scale 1:50000 data will be updated in 
the next five years, the update rang will be covered the whole 
country other than western of China. 
As described in the previous section, there are two methods for 
updating geo-spatial databases. The direct method is basic for 
the geo-spatial database, but its cost of time and economy is 
very high. In fact, because of the inherent links between multi 
scale geo-spatial databases, the smaller scale database can be 
updated with the larger scale one. In other words, it is not 
necessary to use the direct method to update geo-spatial 
database at each scale. In the practical surveying and mapping, 
the larger scale databases often have shorter updating period 
than the smaller scale ones. In China, for example, geo-spatial 
data at scale 1:10000 are got to update every 3-5 years, but the 
updating period of the scale 1:50000 is 5-10 years. Therefore, 
it is reasonable to update the smaller scale database with the 
larger scale one since its cost of time and economy is less than 
the direct updating method. 
The huge requirements have attracted lots of researchers from 
many fields including GIS, surveying, and spatial database. 
Especially, more efforts are directly from researchers in the 
field of map generalization since this method of updating 
between multi scale databases is based on map generalization. 
22 Technological difficulty in updating based on map 
generalization 
It has been recognized that updating smaller scale geo-spatial 
data with larger scale geo-spatial data is one of objects and 
tasks of map generalization in current information age [Li, 
1999]. With the development of pattern recognition, 
Computational geometry, spatial database and other information 
technologies, map generalization is becoming automatic and 
intelligent. The data result of map generalization can be used as 
the updated data result. Also, as another way of updating, 
Change information can be generalized at first and then update 
the smaller scale data. Therefore, geo-spatial data updating 
require intensively map generalization technologies in the 
digital environment, in fact, this requirement has been one of 
màn drives for the development of | map 
Pao alization[K ilpeláinen and Sarjakoski, 1995; Badard, 
999]. 
Since 60s in the last century, a lot of models and algorithms for 
Map generalization have been presented. The researches involve 
the generalization operation of point, line, and area features. 
Also, some researchers explored the operators, framework, 
knowledge rules of map generalization (Li etal., 2004). Some 
of them can be employed as edit tools of data handling. Some 
commercial GIS software such as ARCINFO presented related 
tool package for generalization based on these researches (Lee, 
2001). However, it should be recognized that these research 
results have not been resolved the problems of map 
generalization completely, as Jones pointed out, the whole field 
of automated generalization is still in quite an immature state 
(Jones, et. al. 2000). 
In fact since map generalization walked into in the digital 
environment, the contents and ranges of map generalization has 
changed greatly, for example, the emphasis has not been the 
generalization of paper maps, but become the visualization and 
application analysis of geo-spatial data. In the situation of multi 
scale updating, map generalization technologies are also 
completely different from the traditional map generalization, 
there are some problems to be resolved, for example, it should 
be considered to combine the change detection and map 
generation operations, also handle the relation between the old 
and new geo-spatial data, and so on. 
3. GEO-SPATIAL DATABASE UPDATING BASED ON 
MAP GENERALIZATION 
3.1 Primary rules 
Geo-spatial database updating is a complex procedure. 
Especially, updating based on map generalization involves lots 
of data sources and materials. It is reasonable to make basic 
rules as starting point for the desigment in order to decompose 
the complexity. Based on the requirements of in multi scale 
geo-spatial database based on map generalization and 
considering the technological level of map generalization, the 
possible rules should be considered including at least the 
following points. 
(1) Balance between spatial database and mapping 
As known, spatial database is different from paper or visual 
digital maps, for example, more aspects about cartography such 
as displacement are necessary to be considered in the mapping 
procedure, but not for a spatial database. Therefore, while 
updating a geo-spatial database, one may not consider about 
much aspects about the cartography effect. 
(2) Combination of automatic and human-computer interactive 
operation 
Because the whole field of automated generalization is still in 
quite an immature state (Jones, et.al. 2000), a practical and best 
choice is to make the combination of automatic operation and 
human-computer interactive. In practical situation, many 
operators of generalization could not be applied to all cases, so 
both automatic and interactive operations are provided. 
(3) Integration of different updating procedures 
Geo-spatial updating includes many procedures, for example, 
data sources handling, change detection and extraction, edit of 
generalization, confliction detection and resolution, quality 
check and so on. For an operator, to some degree, his working