m
Figure 5: A low-detail model of approximately 2000
buildings in Vienna
5 SUMMARY / OUTLOOK
This paper outlined a concept for storing big 3D datasets of
urban environments. Special focus was given to fast visual-
ization. It was proposed to organize the data as one big LOD
model. For any part of the data geometric models in several
quality levels can be used to render the scene.
On the database level, the LOD model can be stored in an
R-tree. The nature of the data (hierarchical organization,
mainly geometrical or binary data) makes the choice of an
object oriented database obvious.
The implementation of this system is the first step toward a
complete database system for a 3D urban GIS. The next step
would be a graphical user interface which allows interaction
with the data.
5.1 Building an urban Geo-Server
To make the data available to a geographically dispersed
community, techniques to distribute the data between sev-
eral database servers and to update datasets over the network
need to be developed. The implementation could be based on
the concept for a distributed central / local server concept
proposed by [Reh1 96]. Although this server (GDSS, Graz
Distributed Server System) is intended to achieve a unified
access to remote sensing image data, there are more or less
the same requirements as for the Cybercity project: network
managment, transparent data exhange and database queries,
user interaction etc.
To achieve acceptable response and transmission times, a
high speed network backbone (probably ATM) must be used.
ATM will most likely become an integrationg network in the
near future. It is designed to carry all existing and future data
services including traffic with a time relation — e.g. voice and
video — as well as data with transmission speeds up to 2.4
Gbit/sec [Pry 94, Reh2 96].
Finally, the entire dataset would be stored only at one or a few
central servers; reduced datasets could be stored locally, e.g.
all data of district Xyz in the municipal administration office
Xyz, all data about telephone lines in the office of a telecom-
munication company and so on. This concept of an urban
Geo-server would lead to a new dimension of GIS application.
202
REFERENCES
[Bro 92] Brooks F. et al: Six generations of building Walk-
troughs. Technical Report TR92-026, University of North
Carolina, Department of Computer Science, 1992.
[Cla 76] Clark J.H.: Hierarchical Geometric Models for Vis-
ible Surface Algorithm. In Communications of the ACM,
19, 10 (October 1976), pp. 547-554.
[FS 93] Funkhouser T.A., Séquin C.H.: Adaptive Display Al-
gorithm for Interactive Frame Rates During Visualization
of Complex Virtual Environments. In Siggraph 93 Com-
puter Graphics Proceedings, pp. 247-254.
[Fun 93] Funkhouser T.A.: Database and Display Algorithms
for Interactive Visualization of Architectural Models. Ph.D.
thesis, University of Berkeley
[GMB 95] Gruber M., Meissl S., Bohm R.: Das dreidimen-
sionale digitale Stadtmodell Wien. Erfahrungen aus einer
Vorstudie. In: VGI (Osterreichische Zeitschrift fiir Vermes-
sung und Geoinformation) 1+2/95, pp. 29-36
[GPL 95] Gruber M., Pasko M., Leberl F.: Geometric versus
Texture Detail in 3D Models of Real World Buildings. In:
Proceedings of the Ascona Workshop 95 on Automatic
Extraction of Man-Made Objects from Aerial and Space
Images. Birkhäuser, Basel 1995.
[HG 94] Heckbert P.S., Garland M.: Multiresolution Model-
ing for Fast Rendering. Proceedings of Graphics Interface
'904, Banff, Alberta, Canada, 1994.
[KLR 95] Koller D., Lindstrom P., Ribarsky W., Hodges L.F.,
Faust N., Turner G.: Virtual GIS: A Real-Time 3D Geo-
graphic Information System. GVU Technical Report 95-14,
Georgia Institute of Technology, 1995.
[MD 96] Maresch M., Duracher P.: The Geometric Design
of a Vehicle Based 3 Line CCD Camera System for Data
Acquisition of 3D City Models. In.: Proceedings of ISPRS,
Vienna 1996.
[MS 95] Maciel P.W.C., Shirley P.: Visual Navigation of
Large Environments Using Textured Clusters. 1995 ACM
Siggraph Symposium on Interactive 3D Graphics, pp. 95-
102
[Pry 94] Prycher M.: Asynchronous Transfer Mode. Prentice
Hall, 1994.
[Rehl 96] Rehatschek H.: Preliminary Design of a Dis-
tributed Planetary Images Data Archive Based on an ATM
Network. In: Proceedings of the Visual 96 Congress, pp.
68-78, Melbourne 1996.
[Reh2 96] Rehatschek H.: A concept for a Network-Based
Distributed Image Data Archive, Proceedings of ISPRS,
1996.
[RG 95] Ranzinger M., Günther G.: Changing the city:
datasets and applications for 3D urban planning. In GIS
Europe, 3/95, pp. 28-30
[SBM 94] Schneider B., Borrel P., Menon J., Mittleman J.,
Rossignac J.: BRUSH as a Walkthrough System for Archi-
tectural Models. IBM Research Report RC 19638, 1994.
[Sin 93] Singer C.: Relationale Datenbanksysteme als Ba-
sis geographischer Datenbanken. In Geo-Informations-Sy-
. steme 6/1993, pp. 9-16
[SS 95] Schaufler G., Stürzlinger W.: Generating Multiple
Levels of Detail from Polygonal Geometry Models. In Pro-
ceedings of 2nd Eurographics Workshop on Virtual Envi-
ronments, Monte Carlo, Monaco, 1995.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996
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