! 2004 
RESEARCH THE CHANGE OF THE BUILDINGS BEFORE AND AFTER 
EARTHQUAKE BY USING AIRBORNE PHOTOGRAPHS 
Y. Sidar", B. Bayram®, C. Helvaci®, H. Bayraktar”* 
*YTU, Civil Engineering Faculty, 34349 Besiktas Istanbul, Turkey - (bbayram, chelvaci, hbayrak)@yildiz.edu.tr 
? Ugur Harita Muh. Burosu, Alemdag Cad. No:210/1-B, Umraniye Istanbul, Turkey- ysidar@yahoo.com 
Commission VII, WG VII/5 
KEY WORDS: Earthquake, Change, Detection, Photogrammetry, Geometry, Statistics 
ABSTRACT: 
Recently the possibility of an earthquake has become one of the most important subjects in lots of countries especially in Turkey. 
For that reason, the possibility of an earthquake gains ground due to its devastating physical and psychological effects. Because of 
these physical losses and its psychological effects, people who experience the earthquake generally become sensitive and provident. 
Although disaster management had been established before the earthquake, the studies after the earthquake prove the fact that 
decreases in the loss of lives is inadequate. In this study, the aerial photographs have used which have been obtained before and after 
the earthquake. An algorithm is developed that determines the damaged buildings as semi-automatic. The principle of this study is 
analyzing the buildings’ image histograms and determining their conditions. Gólcük and Adapazan regions before and after the 
earthquake have been used for the analysis of the image histograms that belong to the buildings in the aerial photographs. Our 
empirical results have shown that the histograms of the undamaged and damaged buildings have different forms. For this reason, 
utilizing the histogram analysis, the conditions of the damaged buildings have determined by using a semi-automatic process. The 
important pre-condition for this study is the digital maps of the study area to be in existence. Briefly, to form the histograms, the 
coverage areas of the buildings that are after the earthquake photographs in vector format are found and the image histograms are 
calculated from those areas. The purpose is to determine the damaged buildings quickly during the earthquake and contribute to the 
disaster management. It is thought that, through the results that are to be obtained, it will be possible to direct the rescue mission 
correctly, estimate the number of loss of lives and take healthy precautions. 
1. INTRODUCTION interpretation of aerial images where we want to assess how 
much specific algorithms and/or features aid in the completion 
The result of development of the computer technology, the of vision tasks. In such vision tasks as target detection, battle 
problems of the photogrammetry and remote sensing are carried damage assessment, delineation of buildings and man- made 
to vector data. Due to the accessibility of advanced software objects, the segmentation map represents an intermediate level 
and hardware systems, it is possible to do computer based intelligence to the human operators (Letournel, 2002). 
photogrammetric process. Also, it is feasible to detect the After natural disasters happen, the damages have to be 
changes through the development of the satellite technology. determined and an effective disaster management has to be 
Monitoring the change is meant to present reliable, quick and conducted in a short time. This was observed to be a very 
up-to-date data relating to the analyzed area to the deciders. important problem in the earthquake of 17 August 1999, 
(Gunduz, 1996). Systematic and effective manipulation of Kocaeli. (Bayram, 2001). 
remotely sensed data is necessary for the utilization of data In this study, aerial photographs which are taken before and 
from resource satellites and low-level airborne platforms for after the earthquake are used. The algorithm and application 
monitoring and analyzing the dynamic phenomena of the which determine the deformation of the buildings after the 
Earth’s surface. Because data capture is sequential over time, earthquake are explained with change detection. 
multiple images for any particular area contain potential 
information about changes of surface features or conditions. 2. APPLICATION OF THE ALGORITHM 
(Raafat, 1991) 
Increasing migration within our country accelerates the change In the pre-researches, the histograms of the undamaged and 
in the usage of lands as well, especially in metropolitan areas. damaged buildings are analyzed. The typical forms of 
To determine the changes, remote sensing techniques play an histograms are shown in Figure-1. 
important role. This process requires using the data sets taking 
in different dates. Environmental factors affect the reliable on 
determination of changing. 
One of the fundamental tasks in image understanding is the 
automated extraction of man-made objects from aerial or space 
borne imagery (Kim, 1999). The extraction of buildings in 
particular, has attracted a lot of attention in photogrammetric 
research (Lammni, 1999). A case in point is the photo- a 
  
* Corresponding author. ' 
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