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The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics
Chen, Jun

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001
Mattias Pfund
îss et. al,
Institute of Geodesy and Photogrammetry
Swiss Federal Institute of Technology (ETH), Zurich
ETH HOnggerberg, CH 8093 Zurich, Switzerland
Tel: ++41-1-633 3045, Fax: ++41-1-633 11 01
ri, Vol. 8,
E-mail: pfund@geod.baug.ethz.ch
The extension of Geographic Information Systems into the third dimension is gaining more and more importance every day. A huge
number of GIS-users need as completion of the usual planimetric representation of the landscape (cartographic maps and 2D-GIS) also
some altimetric data and the volumetric extension of interesting objects.
Today most applications and data structures for 3D GIS are optimised for visualisation. They usually omit topological information in
order to get a better performance. In consequence the functionality provided by this systems is often limited to visualisation and
supports few analysis functions. If however the whole spectrum of GIS functionality we use in 2D-GIS (data acquisition, management,
analysis and visualisation) has to be available for a 3D-GIS, then it needs an adequate geometrical data structure.
This paper first describes the requirements of a suitable topological data structure for a 3D GIS. The goal is to model any object of the
3-dimensional space exactly or at least with a good approximation. Secondly, the implementation of a prototype system supporting a 3D
data structure is described.
2.1 Data Aqulsition and Management
Geographic Information Systems enable a numeric and
abstract description of spatial objects and phenomena of the
the real world. Although our world and the objects situated in it
are three-dimensional, commercial GIS usually reduce spatial
data by its third dimension and project it onto two dimensions.
One of the main reasons for this is the complexity of an
implementation of a complete three-dimensional GIS. First of
all there ist still the requirement of an adequate geometric data
model with an appropriate object building and an extended
topology. Furthermore new methods for data acquisition and
administration must be developped as well as algorithms for
processing and analysis of 3D spatial data (Pfund 1999).
The photogrammetric approach uses the profound knowledge
of the community about the acquisition of 3D data. The main
goal is usually to produce and visualize city models of a finite
area. Starting with a detailed aquisition of the rooftops and a
elevation model, they produce surface models of buildings and
other objects. This techniques are quite fast and accurate. The
disatvantage is, that these methods don’t provide much
thematic information about the objects other than .house’, .tree’
and so on. Furthermore there is no clear concept recognizable
about data management. The prevalent philosophy is: Acquire
once and never touch it again!
For a cuple of years several efforts were made in
order to realize a 3D GIS. Depending upon the
initial position different strategies and system
architectures were used. Basically one can
distinguish between three different approaches,
determined by the data aquisition method: A
photogrammetric, a CAD and a GIS approach. In
order to rate these methods one should keep in
mind the four main tasks of a GIS:
• aquisition (new, import, update)
• management (modeling, modifying, storage)
• analysis (queries, manipulations)
• output (visualization)
From a Geoinformation System point of view, a
software must be able to perform all tasks listed
above. If only one capability is missing partially,
the usability of the system as a GIS is reduced
Fig 1: Different evolution steps on the way to a real 3D-GIS:
a) analogue/digital cartographic maps; b) 2D-GIS;
c) 3D-visualisation of 2D-data; d) 3D-GIS with query functionality
The realisation of a "real” 3D GIS is thus extremely difficult due
to technical and conceptional problems, for reasons of the
complexity as well as the temporal and economic
developpment expenditure for the
CAD systems provide a large amount of editing capabilities for
3D data. Data can be aquired with high precisition and a lot of
details. Because the lack of suitable capabilities for data
Cartographic Map
3D - Visualisation