CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
652 
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