Jigless 
XXII 
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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