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

CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
222
4. ARCHITECTURAL HERITAGE DATA
COLLECTION FOR VIRTUALISATION
Appropriate and accurate methodology for collecting data
required for virtual heritage is an important issue. The realism
of the virtual reconstruction greatly relies on the quality of the
data collected. Therefore, a detailed database covering
numerous subjects have to be formed in order to recreate an
historical building together with virtual humans and activities
realised within this building in virtual environment [7]. On the
other hand, the extent of the scope and the details are directly
related to the building function and the aimed precision. In this
section the methodology developed for creating the database for
acoustical and visual virtualisation of CAHRISMA Project
buildings will be presented and exemplified.
4.1 Methodology of Data Collection
Detailed data on the acoustical and visual properties of the
ancient spaces are required for the virtualisation. Different types
of data, grouped as architectural, functional, acoustical and
visual, have to be gathered in order to create the basic database
for the virtual conservation and restoration of the buildings.
Basic steps of the data collection are designed as follows:
Architectural data
Three basic investigations are required in order to obtain a
complete architectural data:
- Structural and architectural specifications of the
buildings
- Visual properties of interiors and exteriors
- Furnishing
Data related with functional activities
Activities related to the building function have also to be
determined in order to realise the visualisation. People’s
clothing should be considered according to the era that the
visualisation would be realised.
Acoustical data
Acoustic properties of
- Rooms
- Materials used in indoors
- Activities (speech/ music)
should be determined.
Lighting and colour data
For the lighting and colour properties, determination of
- Indoor’s lighting syste ms
- Natural and artificial illuminances
- External daylight illumination levels
- Ancient luminary properties
- Indoor material light reflectance and colours
should be realised.
Steps of the mentioned methodology will be exemplified in the
following sections, based on the Project.
4.2 Collection of the Architectural Data
While trying to recreate historical edifices in virtual
environment, it is important to expose the ancient and the recent
situations of these buildings. For the buildings investigated in
the CAHRISMA Project, it has been detected that some
modifications were occurred due to different reasons such as
renovations, restorations and functional changes through the
time. Therefore the period that will be presented in the
virtualisation has to be determined. 16 th Century has been
chosen for the virtual restitution of Sinan’s mosques because
this was the era they have been built. Almost no great changes
have been occurred in the religious rituals and the objects used
on Islamic prayer throughout the time. At 1054 Roman Church
and Byzantine Patriarch excommunicated each other causing
their definite separation on the liturgical initial, spaces and use
of objects, so the 1 l lh Century has been accepted as the era for
virtual restitution of the selected Byzantine churches [8].
In order to expose the structural and architectural specifications
of the buildings;
-Plans and sections were collected.
-Modifications occurred in time were determined.
-Collected data were compared with the recent
situation by checking measures in situ where necessary.
In Figure 1, an example showing the alterations in one of the
edifices- St. Sophie (Haghia Sophia) Church- is shown [9]. For
the visual properties of the interiors, drawings and photos were
examined. Furnishing of the ancient and the recent situation was
also determined. The data collected under this topic is used as
the database of the visual and acoustical virtual reconstruction
of the buildings.
4.3 Collection and Presentation of the Acoustical Data
As mentioned in Section 2, acoustical data covers rooms,
materials used in indoors and activities. Room acoustical
properties can be determined by measurements and/or
calculations [1, 3, 4]. In the CAHRISMA Project both have
been realised and crosschecked to show the accuracy of the
findings. Measurements were realised by three teams (UNIFE,
DTU and YTU) according to ISO standards and calculations
were done by using Odeon and other softwares [2, 4, 8, 10].
Each space has been elaborated carefully in-situ and surfaces
having different materials in terms of acoustics are identified.
These are shown on coloured drawings (plans and sections) and
used to estimate the sound absorption properties of the indoor
surface materials. An example is given in Figure 2 [1, 11].
Sound absorption coefficients of the materials such as carpets,
tiles and stones are measured in laboratory. The alterations
occurred in time are determined from the available literature in
order to use in the virtual restitutions.
According to the activities realised in the buildings, acoustical
activities such as speech and music have to be determined. In
the CAHRISMA Project, sounds related to religious activities
such as sermons and prayers are specified and recordings in situ
during ceremonies as well as recordings in anechoic chambers
are realised.
-Findings of these works were used in the auralisations created
for the virtual environment.
4.4 Collection and Presentation of the Lighting and Colour
Data
In order to create a realistic virtual environment, lighting
systems and colour of the materials should be determined
precisely. Natural and artificial lighting systems of the
CAHRISMA Project’s edifices were examined in situ (YTU).