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Title
New perspectives to save cultural heritage
Author
Altan, M. Orhan

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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