International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004
3.5 Implementation
Perception is related to the degree of realism experienced by the
viewer. The basic concept of VR is the direct coupling of the
head position and viewing direction of the user with the viewing
position used to generate the image on the display. The head
position of the user is constantly tracked and fed into the
display algorithm to calculate at each moment a correct
stereoscopic and perspective display of the scene. This strong
coupling of the current eye position of the user and the image
offered by the display system, gives the user the illusion of
‘immersiveness’. The ultimate VR-systems completely immerse
the user's personal viewpoint inside the virtual world. A major
distinction of VR-systems is the mode with which they interface
to the user. Current systems range from true immersive to
nonimmersive displays. These involvements allow the planners
a better platform for decision-making and also help laypersons
to understand the complex geographic data, as if they see in
reality.
The users manipulate what is perceived to be "real" objects in
the same manner as they would manipulate them in the real
world, as opposed to the typing, pointing and clicking, one
traditionally uses to manipulate objects when you interact in
other computer environments. For example, to move an object
in a VR environment, you may grab the object with your hands,
lift it as you normally lift objects in the real world, and put it
down wherever you want it inside the virtual environment. Now
the program lets you see the attribute data as well.
4. CONCLUSIONS
Whether the challenge is to pick a location for a new facility or
decide how to construct it, GIS is important in the decision-
making process. By combining 3-D GIS, integrated with
applications like Web3D to share information over Internet and
get input from the public will enhance planning process. When
combined with immersive environments, results are superior to
desktop systems for characteristics such as ‘intuitive working’,
‘real-time interaction’ and ‘full-scale modelling in a 3D
immersive environment’.
3D information systems with a connection to attribute data
could be more helpful in addition to geometry visualization. For
example in the field of underground supply lines, which have a
complex structure. In a large area of network, supply lines are
layered one above the other and so the importance of z
coordinate exists. Planners can visualize the network more
closer may be to find space for new lines or to know details
about with access to attribute data.
The major advantage of Web 3D concept is it can create the
database connection between the 2D shape file and the 3D
VRML model by means geometry and representative point (A
point inside of geometry). So, the creation of 3D VRML model
can be from any source for example aerial photos. whilst the
VRML model should be georeferenced common to the 2D
shape file. The project can be further improved by providing
functionalities of online updating of attribute data and other
thematic queries based on attribute data as well.
The concept of connecting and display of attribute and 3D
geometry for VR visualizations were successful with direct use
of text file created in web 3D part. And a lot of improvements
can be done on the basis of this idea to make it more useful for
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planning applications. The VR application can be further
enhanced to access shape files based on same concept above,
enabling to perform basic functionalities as of GIS software.
4.1 References and/or Selected Bibliography
References from Books:
Pimentel, Ken and Teixeira, Kevin 1993. Virtual reality
through the new looking glass. Windcrest Books, USA, pp. 66-
86
Stuart, Rory 1996. The design of virtual environments.
McGraw-Hill Inc. USA, pp. 97-125
Zlatonova, Siyka 2000. Phd thesis, 3d GIS for Urban
development, Thesis ICGV, GrazUT, Austria and ITC, The
Netherlands, ITC Dissertation Series No69,
http://www.gdmc.nl/zlatanova/PhDthesis/pdf/content.html
References from Other Literature:
Bodum, L., I. Afman and J. Smith, 1998. Spatial planning
moves out of the flatlands, in: Proceedings of AGILE,
Enschede, The Netherlands.
Ousterhout, J., 1993. Tcl and the Tk Toolkit (Addison-Wesley,
Reading, Massachusetts).
Tempfli, K., 1998. Urban 3D topologic data and texture by
digital photogrammetry, in:Proceeding of ISPRS, March-April,
Tempa, Florida, USA, CD-ROM.
User Guide, Cortona SDK 4.1
http://www.parallelgraphics.com/developer/
References from websites:
Blach, R., Landauer, J. Rosch, A., and Simon, A., 1998.
A Highly Flexible Virtual Reality System
http://vr.iao.fhg.de/papers/fgcs98.pdf (accessed Dec 2003)
Finley, Darel. R., 1998. Point-In-Polygon Algorithm.
http://www.alienryderflex.com/polygon/ (accessed Aug 2003)
Morley, Chris 2002. Tool: libVRML97
http://www.vermontel.net/-cmorley/vrml.htm.
(accessed Sep 2003)
VRML '97 Specification.
http://www web3d.org/x3d/specifications/vrml/ISO_IEC_14772
-All/index.html. (accessed Jan 2003)
Warmerdam, Frank 2002. Tool: Shapelib v 1.26.
http://shapelib.maptools.org/ (accessed May 2003)
4.2 Acknowledgements
We would like to express heartfelt gratitude to Prof. Dr. Volker
Coors at Stuttgart University of Applied Sciences for the
continuous support, guidance and motivation throughout the
research. Our sincere thanks to City administration department
(Stadtmessungsamt), Stuttgart for providing the necessary data,
without which, the idea wouldn't have proper fuel. We would
like to extend our thanks to Fraunhofer Research Institute for
industrial training IAO in Stuttgart, for providing software and
hardware for the project part of Virtual reality, especially Mr.
Frank Haselberger for his invaluable support.
