CIP A 2005 XX international Symposium. 26 September - 0Î October, 2005. Torino, ltalv_ 
622 
AN APPROACH FOR REPRESENTATION OF HISTORICAL OBJECTS BY 
MEANS OF 2D WEB-BASED GIS 
O.Akcay 3 , F.Yilmazturk b 
Istanbul Technical University, Div. of Photogrammtery, 34469 Maslak Istanbul, TURKEY- akcayoz@itu.edu.tr 
b Istanbul Technical Univ., Div. of Photogrammtery, 34469 Maslak Istanbul, TURKEY- yilmazturk@itu.edu.tr 
KEY WORDS: GIS, Internet/Web, Orthoimage, Photogrammetry, Visualization 
ABSTRACT 
On the internet, representation of the historical objects needs complex modeling methods such as 3D Cad models, VRML, and 
Textured Models. Due to their complexity, most users have some problems to get the 3D data via internet. Because of low internet 
connection and low RAM capacity, users cannot handle the intensive data easily. To simplify the modeling methods for the historical 
objects or monuments, we designed a new model. This research represents the whole model in two dimensions. Our aim was to 
reduce data amount in our 2D model approach while we tried to keep visualization quality at the similar level with the 3D data. 
Despite limited 2D representation, the model is capable of introducing the whole object properly. To get realistic models in the work, 
orthophotos of the objects are used. The objects are also presented via internet. Moreover, their attributes are added on their 
orthophotos. Finally, we created a Web-based GIS for historical monuments. 
1.INTRODUCTION 
Documentation of cultural heritage objects is not an end in itself 
but serves as a Historical monuments have different irregular 
shapes and dimensions. Some of them are mini tool to make 
information accessible to those (research experts or any 
interested persons) who cannot investigate the object itself. 
Different reasons can be found for the necessity of this 
information transfer: 
• The object is not accessible to interested parties 
• (e.g. rock paintings in caves). 
• The object is too large or too complicated to be 
overlooked and it would be too time consuming to 
execute an own investigation. 
• The object (or just a part of it) is visible only for a 
short period of time at its original location (as in 
archaeological excavations or when unearthed during 
civil engineering projects). 
• Persons living far from the object cannot afford to 
visit it. 
• The object is in danger of slow deterioration valid for 
inside of a room or a building, (environmental factors) 
or sudden destruction (earthquakes and other natural 
disasters, war and After photos are taken in the center 
of an object, it is vandalism) (F.Karsli, E.Ayhan, E. 
Tunc). 
The aim of this work is to create a simple method to 
represent 3D objects on the internet. We handle 
representation in two dimensions. Although two 
dimensions have some restrictions, it deals with more 
compact data thana big amount of data. 
Therefore, two-dimensional model is considered to 
represent 3D objects. The concept, in the paper, put 
forward a representation model in two dimensions. 
Web-GIS is improving very fast depending on worldwide 
network. Users with high speed connected intenet demands 
more data in their PC. Therefore providers have a good 
opportunity to introduce their data to end users. To process 
this opportunity effectively, providers have to maximize 
modelling concept to get more audience. 
Historical monuments have different irregular shapes and 
dimensions. Some of them are mini object while some of 
them are huge and complex objects. Especially the work is 
suitable for representations of big and complex objects. 
2. REPRESENTATION OF 3D OBJECTS IN 2D FOR 
WEB-GIS 
In the concept, an object should be represented by orthophotos. 
Images has got their coordinates by orderly. End of an image is 
start of next image. The concept is applicable for either inner or 
outer of an object. 
2.1.Representation of the Inner of an Object 
Representation of an inner of an object is mostly valid for inside 
of a room or a building. 
After photos are taken in the center of an object, it is registered 
for a local coordinate system one by one. 
However local coordinates must have a relation amongs 
orthophotos. If the object has not a rectangular shape, pictures 
may be taken from different places. So more good aspects can 
be catched for creating orthophotos. Figure 1 taking image step. 
Figure 2 explains registration of local coordinate system. 
In Figure 1, at first image station side a, side b and side h; at 
third image station side e, side f and side g are taken. Therefore 
8 orthophoto represents walls of the room. The local coordinates 
will be like following figure. (Figure 2). 
Base and ceiling also are possible to represent at the local 
coordinate system. Base of the room places below the sides. 
Figure 3 shows a room with its ceiling and basement. 
a 
Figure 1. Taking images.