CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
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method in stratification based studies, where the layers
necessitate to be studied first separately and then altogether, so
as to understand each layer together with their position within
the whole. Thereupon, in this study, the components making up
the urban form of each phase are documented as they appear at
the interface and studied separately, which are then put all
together to form up the whole information system.
Keeping this basic guiding principle in mind, stratigraphic
recording and representation phase is handled in two steps,
which are common to all GIS based studies. Those are, data
collection, entry and correction and data storage, structuring
and retrieval.
Data Collection, Entry and Correction: The first step of this
phase is to collect and classify the raw data concerning the
predefined units of the study. For this, an extensive literature,
archival and site survey had been carried on so as to provide
data about the urban form of Bergama in different periods.
Basic data sources of this study have been, historic maps,
engravings, old drawings and photographs, drawings produced
during archaeological excavations, plans concerning different
periods of the town, existing maps, contemporary photos, aerial
photos and satellite images, travelers’ books, reports of plans
and projects, reports of archaeological excavations, articles and
books concerning different aspects of the urban form,
inventories of the registered buildings. Besides these basic
sources of data, site survey is always the most important data
source concerning the existing situation of the remains and
traces belonging to different periods.
The quantity and context of data concerning the urban form are
not homogeneous for all the units defined for the study. There
are intensive and directly utilizable data about the urban form
and architectural components of Hellenistic and Roman
Pergamon, owing to the lately prepared studies of Dr. Ulrike
Wulf-Rheidt (1994) and Prof. Dr. Wolfgang Radt (2002; 1993;
1988; 1984), which are built upon the results of excavations and
researches carried by the German archaeologists since the 19th
century onwards. Whereas, the data concerning the urban form
of Byzantine era, for which also the main data source is
archaeological excavation (AVP XV2 1991), are not as
extensive and directly utilizable as those concerning the
Hellenistic and Roman eras. Among all, Principalities era is the
most disadvantageous one with respect to the data sources, as
there are very few documents or existing remains belonging to
this period from which data about the urban structure can be
provided. There is a variety of historic and contemporary visual
and written sources concerning the Ottoman era, most of which
provide data about single structures, mainly the monumental
buildings, such as mosques, khans, and market places.
However, the main data source, which provides data concerning
the whole Ottoman urban tissue, is 1904 map of the town
prepared by German cartographer Otto Berlet (AVP I 1913).
Besides, site survey is an important data source for Ottoman
era, owing to the still standing structures belonging to this
period.
The data concerning the existing situation of the urban form
come from various plans and maps, among which 1/1000,
1/5000 and 1/25000 existing maps set up the basis. However, as
these maps are dating from 1960 and have not been revised
since then, site survey had to be carried on to update the main
features. Besides, during the site survey traces remains referring
to the historical stratification that can be observed within the
contemporary town are also documented.
Collection of raw data is followed by their classification
according to the defined units of the study and conversion into
digital format. For digital data production, AutoCAD R14 is
used instead of direct entry to GIS, mainly because such a study
requires detailed drawings which are not so easy, and even
sometimes impossible, with the less drawing and editing
capabilities of GIS when compared with CAD softwares (Bilgin
Altinoz 2002: 46-50; Bilgin Altinoz, Erder 2000: 43-49).
Therefore, all the visual raw data sources have been transferred
into the computer environment by scanning and then transferred
as raster image into AutoCAD R14, so as to be converted into
vector format by on-screen digitizing.
Prior to vectorization process, the elements of analysis, which
will be represented as spatial data in GIS data structure, should
be determined. The elements of analysis are determined both
according to the main components of urban form, which are
common to settlement patterns of different eras and in relation
to differing levels of geographic space. Topographical features,
such as sea, lake, river, hill, mountain, plain, woods, break in
the terrain and contours and inclination of the terrain, are the
elements of analysis which are necessary to understand the
urban form in all the levels of geographic space. Level of
territorial organization comprises the other urban and rural
settlements within the territory of the town and the territorial
network constituting of roads, railways, paths, etc., between
them. Level of settlement layout organization concerns with the
settled areas of the town, their extent, characteristics,
boundaries and the entrances to them. Level of intra-settlement
organization embraces streets and building blocks, their extent,
outline and axis. In the level of building block organization, the
extent and outline of edifices, walls and remains are considered.
Besides the components of urban form, there are other elements
of analysis, regarding the provision of legal and operational
basis for conservation decisions and implementations, such as
areas designated for different types and degrees of ‘sites’,
elements related with references used in existing maps
(coordinate system, topographical measurement points, texts
etc.), administrative boundaries (municipal boundary,
contiguous area boundary, etc.), built-up areas, separators,
sidewalks and the like.
According to the defined elements of analysis and the type of
geometry (area, line, point) to represent them, the digitizing
process is carried on so as to prepare the spatial objects of the
information system. During this process,
The digital data production has been carried on primarily for the
existing situation of the town through the different scaled
existing maps. For this, first of all, an existing digital map of
Bergama is obtained, by vectorizing 1/1000, 1/5000 and
1/25000 maps reflecting the existing situation and
georeferencing them all. Taking the digital existing map as the
basis, required elements of analysis for different stratigraphic
units of the study are produced in vector format as different
layers, by using various data sources. As a result, a (.dwg) file
for each of the stratigraphic unit as well as the existing situation
have been obtained, which are then combined so as to control
the correctness of all the geographic relation between them.
The major difficulty during this phase has been the unification
of raw data coming from various sources in different format,
detail and accuracy, so as to provide a single spatial data set for
each of the stratigraphic unit.
Data Storage, Structuring and Retrieval: Constitution of
GIS Data Model: Following the data collection, entry and
correction phase, data storage, structuring and retrieval are
realized as a result of which the GIS data model of the study is
set up. In structuring the GIS data model of the study, elements
of analysis concerning each stratigraphic unit correspond to
spatial data, while, information types concerning each element
of analysis refer to attribute data, which altogether comprises
the geographical objects.
When the requirements of spatiotemporal data representation
