CI PA 2003 XIX 11 ' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
Das Haidcntor - 
CARNUNTUM 3D 
Rekonstrukiicnsvorschlng 
(Pohanka 1982) 
Picture4: screenshot of the application "Carnuntum 3D" 
For the project Carnuntum this step is one topic of present 
research. 
In addition there is the need for a uniform metadata structure, 
which would help to classify objects and their usage in specific 
scales. 
4.2Realisation 
The implementation in Director requires a conversion from the 
source file format, which can be VRML as well, to the 
shockwave3d “*.w3d” format. Several 3D modelling software 
packages support this export, but it must be taken into account 
that the converting of hundreds of files would probably take too 
long. 
For this reason a converting and exploration tool called ‘‘deep 
exploration” is available for the PC platform. Apart from 
supporting a batch conversion tool, the camera-, light- and 
texture settings may be changed too. 
Inside the authoring software a 3D world with a coordinate 
system according to the display plus a z-axis is available. The 
position of models must be transformed to match this local 
system. 
For objects lying on the surface only the position coordinates 
are required. For the height the models' zero height is 
intersected with the surface model. 
Surface models may be calculated directly in the application 
following different algorithms, like a regular grid, taking a 8 or 
16 bit grayscale image as source. The advantage of this 
technique is that only a small picture file is transferred via the 
internet, which is very time effective, also for slow internet 
connections. 
Contrary to this a ready made model of the surface, coming 
from any GIS or photogrammetric application, may be streamed 
into the 3D world and thus does not require much power of the 
processor for the calculation. 
A mixture of both ways is useful. The streaming method is used 
for high detailed surfaces, while regional overviews with less 
detail are calculated directly. 
In the area of textures Director supports any kind of bitmaps. 
To activate a texture, a shader has to be created, which may 
consist of eight different textures. Because alpha channels are 
supported, the combination of different textures is possible too. 
OKHMMC CARNUNTUM 3D 
Rekonstruktionsvorschlag 
(Pohanka 1982) 
Picture5: screenshot of the application "Carnuntum 3D" 
an animated texture must be programmed in a way that an 
actual texture member is changed with a following one. 
The used objects are categorised due to their representation and 
scale. Beginning with the high detail model, simplifications will 
lead to the first symbols. At some point two different houses 
from the high detailed mode, will have the same shape in a low 
detail mode. So the symbol catalogue is getting smaller the 
smaller the scale and detail is. 
For the project Carnuntum the creation of symbols is in 
progress. Until now no serious problems occurred. 
5.RESUME 
The main technical problems that exist at the moment are 
dealing with the dynamical generalisation especially by 
switching the scales in large scale views, when a lot of data 
have to be read from the database. Then the interactivity - the 
most important multimedial aspect - is inactive for a moment. 
Another challenge is the changing from a 3D projection view to 
a globus view. This step has to be solved for the idea, that this 
application could serve as interface to a cultural heritage 
database. 
In general there are three main questions this research is 
concerned with: 
- How can a cartographic multimedia application be 
developed to become an important tool for the expert? Is 
there a need for such a exploration tool and if yes, what 
kind of tools are needed? 
- How can a dynamic generalisation be established in a three 
dimensional world? First steps are made with the Level of 
Detail (LoD) techniques. But the influence on how the 
simplification of geometry is done is limited. The 
possibilities of aggregation and displacement have to be 
explored. 
- The role of the visualisation tool as an interface to a 
database or content management system. This essential step 
may enable the techniques of multimedia cartography to 
communicate the content of a database, which could play an 
important part in saving cultural heritage. 
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