ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001
276
Figure 7: visualising 2D and 3D data in one environment
To access the data and to view the results of queries a viewer
will be built on top of the geo-DBMS. It will be examined how the
data can be viewed administratively, as well as two-
dimensionally (traditional GIS interface) and three-dimensionally
(perspective, stereo) and in combination with each other in one
environment (see Figure 7). Possible techniques, which will be
looked at, are 3D Java and (geo)VRML.
7. CONCLUSION AND FUTURE WORK
In science and in applications, there is a tendency to model the
world in multi-dimensions. However, it will take considerable
time until geo-data and applications are capable to model the
world (fully) in 3D. Moreover, a 2D approach still suffices in
many cases. It is therefore relevant to look at a combination of
2D spatial data and 3D spatial data in one DBMS-environment.
At the Department of Geodesy of the Delft University of
Technology a research has been started on this topic. This
article described concepts developed so far concerning the
incorporation of 3D geo-objects in an existing 2D geo-DBMS and
the translation of these concepts into prototype implementations.
This means data definition, data manipulation and data querying
of 2D and 3D data in one environment.
The starting point is to represent and maintain spatial features
within a conventional DBMS instead of handling these outside
the DBMS (in GISs). The support of spatial data types in a geo-
DBMS include:
spatial operators (or geometry functions);
spatial indexing;
spatial clustering;
topology management.
The data model that is currently used to represent 2D features is
being extended with a 3D model extension. Possible data
models studied in this research to represent 3D geo-objects are:
using self containing 3D geometric data types;
using a topological model to maintain and retrieve 3D
objects.
Future work will focus on obtaining the required geo-data to
represent 3D real world objects in the DBMS. This is the relevant
data needed to store the geo-objects in the DBMS and will
consist of the bounding envelope of the object, defined in a
national spatial reference system.
Further research is carried out to query and view 2D and 3D
data in one environment. The required queries are being defined
and will be implemented in the geo-DBMS.
Finally, this research will lead to the implementation of all these
aspects in one system: a geo-DBMS supporting 2D geo-objects
and 3D geo-objects as well as in combination with each other.
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