TECHNOLOGIES AND STANDARDS ON SPATIAL DATA SHARING
Jianya Gong‘, Lite Shi", Daosheng Du', Rolf A. de By?
! State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University,
No.129 Luo Yu Road, Wuhan, China, 430079
? Department of Geo-information Processing (GIP), ITC
Hengelosestraat 99 / P.O. Box 6, 7500 AA Enschede, THE NETHERLANDS
Commission IV, WG IV/2
KEY WORDS: Spatial data, Sharing, Interoperability, Standards
ABSTRACT:
The issue of geo-spatial data sharing has long been a problem to be solved by experts in the field of geo-spatial information science
and technology. Many studies have been carried out over the last years. With decades of efforts, this issue has basically been solved.
This paper reviews the research course of technologies and standards on spatial data sharing and introduces the technical and
standardization systems for spatial data sharing.
1. INTRODUCTION
With the development of geographic information
technology, the geographic information system (GIS) is
transiting from project application to organizational
and social applications. A large number of GIS
applications have been established by various
organizations. At the same time, plenty of geospatial
data have been collected as well. In many geo-spatial
applications, it is necessary to transfer spatial data
between different organizations, with different contents
and in different forms for synthetic utilization.
However, since the spatial databases of different
organizations may have been established at different
times, are based on different platforms, or have been
made to fit different industries or departments, large
differences exist between them. That is to say, they are
largely heterogeneous. The differences are reflected in
the following aspects.
1.1 Differences in Data Contents and Data Sources
Generally speaking, there are three types of spatial
data.
Vector data — This may be the scanned map data after
vectorization, or data obtained from digital surveying
or other means.
Image data — The major sources are aerial photographs
and satellite remote sensing. The data is stored in the
format of raster data.
Topographic data — This type of data is generally used
to describe the elevation of the Earth’s surface. The
sources are map scanning vectorization and digital
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photogrammetry. There are four forms including
contour line, TIN, grid and the combination of TIN and
grid.
1.2 Differences in Spatial Data Model
In general, different spatial database management
systems support different spatial data models. For
instance, there might be spatial data models with or
without topology, supporting 2D, 2'4D or 3D spatial
data, or even spatio-temporal data.
1.3 Differences in Software Platform
For various reasons, different GIS software platforms
are adopted by different spatial database management
systems. Thus, these databases may have different data
formats. Though the original data in the databases
might be the same data set, the spatial database models
may be different.
Since GIS came into being, the defects of GIS
technology have becomie more apparent in spite of true
improvements of the technology itself. Using their
specific data formats, data storage and processing
methods, traditional GISs are closed and isolated
systems, without standards. The GISs and their
application systems were based on dispersed,
independent and closed platforms, causing substantial
conflict in data semantics. Thus, they did not
accommodate data sharing between application
systems well. As a result, the development potential for
geographic information processing technology was
restricted to a large extent.
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