This interface allows programmers to establish a 
connection between a web page and an embedded 
VRML browser window, thus providing a possibility 
to manipulate the VRML scene depending on user 
requests on the web page. Using this possibility the 
interactivity is not limited any more to the purely 
VRML scene but also external systems can be 
connected. In this way, the VRML model can be 
used as kernel of an interactive spatial information 
system [Dorffner L., Forked G., 1998]. 
5 SUMMARIZING REMARKS 
Experience proves the dramatically growing 
importance of interactive virtual worlds in future. 
Being aware of this development an additional 
SCOP module (ATM) has been developed. This tool 
provides an easy way to export a terrain model and 
an orthophoto for interactive 3D visualization using 
the data format VRML. 
The determination of user defined viewpoints and a 
camera path for an automatic animation enables a 
presentation of terrain data in an impressive way 
even for non VRML experts. Using the possibilities 
of distributing VRML worlds over the internet low 
resolution terrain models can be made available to a 
great public without additional cost for a viewing 
software. 
By using VRML for interactive visualization 
additional information apart from geometry and 
texture can be linked to the three-dimensional 
photo-model. Complex spatial and thematic 
situations can be shown in a really vivid way. 
The use of EAI enables a close connection between 
web-sites and VRML scenes. So external data-base 
systems can be made available to the user from 
within the VRML scene. 
Kraus K., Jansa J., Kager H., 1997. "Photogrammetry, 
Volume 2". Ferd. Dümmlers Verlag, ISBN 3-427-78694- 
3. 
References from Other Literature: 
Clark J.H., 1976. "Hierarchical Geometric Models for Visible 
Surface Algorithm". In Communications of the ACM 19, 
10, pp. 247-254. 
Gruen A., 1998. "DTM Generation and Visualization". 
Symposium on Digital Photogrammetry, Istanbul, Turkey 
Kotier M., Rehatschek H., Gruber M., 1996. “A Database for 
a 3D GIS for Urban Environments Supporting Photo- 
Realistic Visualization”. In: International Archives of 
Photogrammetry and Remote Sensing, Vienna, Austria, 
Vol. XXXI Part B2, pp. 198-202. 
Zeisler Ph., 1999. “Nutzung von VRML für 
Informationssysteme basierend auf 3D-Photomodellen”, 
Diploma thesis at the Vienna University of Technology, 
Vienna, 1999. 
The VRML Repository, http://www.web3d.org/vrml/vrml.htm. 
External Authoring Interface Working Group, 
http://www.vrml.org/WorkingGroups/vrml-eai/. 
REFERENCES 
References from Journals: 
Dorffner L., Forked G., 1998. "Generation and visualization 
of 3D photo-models using hybrid block adjustment with 
assumptions on the object shape". ISPRS Journal of 
Photogrammetry and Remote Sensing, Vol. 53 No. 6, 
pp.369-378. 
References from Books: 
Carey R., Bell G., 1997. "The Annotated VRML 2.0 
Reference Manual", Addison-Wesley Developers Press, 
ISBN 0-201-41974-2. online version: "The Annotated 
VRML97 Reference Manual", 
http://www.wasabisoft.com/Book/.