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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
These maps are generally rendered in a pictorial format such as
PNG, GIF or JPEG, or occasionally as vector-based graphical
elements in SVG. Here we choice the SVG format as our web
services output format. SVG documents are sent to client (with
SVG Viewer) by the Web application Server. The system flow is
that client sends a request, then Web application server accept
the request and call the corresponding operation defined by
WMS specification, and the data stored in different GIS platform
has to be. exported into GML documents which have to be
changed into SVG format by the data exchanging components.
At last, SVG is returned to the client and shown by SVG viewer.
Client
Browser Browser
HTML/XML/ SVG Viewer HTML/XML
Î SVG Î
Web
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&IIS/Apache/tomcat/Servlets /tomcat /Servlets server
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I Web
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components components components
| 1 Database
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GeoSurf
Fig. 2 The structure of XML-based spatial data interoperability
system
4. IMPLEMENTATION
The data of Chinese administrative division scale at 1:4,000,000
are stored in the three different GIS software platforms of
ArcInfo, Geostar and Geosurf on the data format required by
respective system. But in each system the data is not integrity.
The data such as BOUNT (the borderline of national provinces)
and RIVER (the borderline of rivers) are stored in the ArcIMS
system by the ArcInfo platform, which is showed in Fig.3 (a).
The data such as ROAD (the midline of road) and ZHUIJI (the
Annotation of national provinces and cities) are stored in the
Oracle database on the platform of Geostar, which is showed in
Fig.3 (b). The data such as LAKE (the borderlines of lakes) and
169
RAIL (the national railways) are stored in the Geosurf platform
by the file format.
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Fig.3 The data of Chinese administrative division scale at
1:4000000 stored in the different GIS platforms
The spatial data interoperability and visualization system based
on XML gets GML format document by the data exporting
components changing the data stored in ArcIMS platform, in
Orcale database for Geostar platform and in the file system for
Geosurf platform respectively. The second-development
functions provided by ArcIMS can export the data into GML
document, and the components of Geostar4.0 has the function to
export the data stored in oracle database into GML document.
JavaBean components of Geosurf4.0 have the same function.
The web services and web application server are programmed by
Microsoft Visual Studio .Net. The system overlaps the GML
data with each other and obtains the data information within the
required envelope. Lastly use SVG exporting components to
change the output GML data stream into the SVG data which
will be send to client for the operations such as browser, zoom in,
zoom out, etc. The result is showed as Fig.4.
