Jigless
XXII
,
Cöltekin, Arzu
VRML AS A TOOL FOR WEB-BASED, 3D, PHOTO-REALISTIC GIS
Arzu Cöltekin, Henrik Haggren
Helsinki University of Technology, Finland
Institute of Photogrammetry and Remote Sensing
Arzu.Coltekin@hut.fi
Henrik.Haggren@hut.fi
KEY WORDS: Reverse Engineering, VRML, Geometry, Web, Texture Mapping, Photogrammetry, GIS
ABSTRACT
As VRML (Virtual Reality Modeling Language) becomes more and more a common and accepted standard for
visualizing vector graphics on the WWW (World Wide Web), the discussions on whether it has a realistic potential in
utilizing geographical information are also often heard. There are serious efforts spent on developing the VRML to
meet the specific needs of geographical information.
In this publication, an indoor 3D model is presented with the summary of the creation process and an analysis of
VRML’s potential as a tool for web-based, 3D, Photo-Realistic GIS is given based on the experiment and literature.
1 INTRODUCTION
1.1 The VRML
The VRML is an interpreted 3D modeling language introduced as a standard in 1993 and VRML97 a recognized
standard (ISO/IEC14772) in 1997. The models created using this language require a VRML browser (such as Cosmo
Player, Corona, Live3D...) to be visualized. Most of the major CAD software include import/export functions from/to
VRML file format (.wrl) for their 3D models in these days.
Although it has many performance limitations -mainly because it is an interpreted language- it has also many
advantages: it is available nearly in all platforms, it has a wide audience and it is cost-effective (Gahegan, 1999).
The GeoVRML Working Group under VRML Consortium is putting an effort to make the language more compatible
for representing geo-referenced data.
1.2 Web-based GIS and Photogrammetry
There is a big demand for photo-realistic scene models so for the techniques relating to it from varying fields and it is
no question everyone wants to have it available on a network. The on-line mapping and GIS (Geographical Information
Systems) applications are now commonly available in varying qualities, mainly in 2D while photo-realism is more
demanded in 3D applications, logically. Photogrammetric methods are used often for data collection for creating such
3D models, but equally needed when the phase for texture mapping arrives.
In following chapters you will find a 3D-model creation and its conversion process to a VRML model.
2 REVERSE MODELING: THE 3D MODEL CREATION PHASE
First of all, the creation of a geometrically reliable 3-D model has its own aspects. In this study, close-range
videogrammetry and “reverse modeling” (method developed by Haggrèn et al., 1993-1996) techniques are used for
modeling process (Haggrén et al. 1997). Then, the models are transferred to VRML models to increase the accessibility
and publicity, which are important issues for a GIS.
Reverse Modeling. Instead of making the measurements and deal with the data afterwards- to make the model, one can
make a visual-model (meaning no geometry considered) based on single video frames (no stereo images). Then make
measurements on wire-frame model as well as on the image, and “rectify” the model onto the image iteratively from
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 143