International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
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2. ORTHORECTIFICATION | mu 
3.WATER QUALITY CLASSIFICATION alt 
General attributes of the data used in orthorectification It 
rocess of the IKONOS imagery: 4 pc 
p gery 3.1 Aim Sti 
ioital elevati ata: n aon 4 : : : ot 
Digital clevation data: 3 The objective of the study is to form a correlation between the : 
The DEM used within the Istanbul city boundry(5343,02 cult of i ; aid] : mn 
km? btained usi | ; hods. The d pixels of the IKONOS image and water samples which were ef 
an^) was aine Sing ora ric ethods > dat: : : : : ; e 
em yw as 0 m amm RES e C collected from the intersections of the lake and polluter carrier P 
‘eo € e d . as : 3 t € É . . . 
So a =. Fia i mS a dle iy a mm main stream branchs at the same time when the image was W 
Cxtenssoneg and Xz coor inates is present). It is made ‚kon ‚The points that were to be used in sampling the water : 
according to the 1/5000 scaled map areas and has 50m spaced = SN : n ici pl 
int u C Erd ı : 86 He "ASC fi were determined by field study one day before the acquistion ch 
a uno Brdas seine $. > > was : : 
pomis. wsing “(das Hmaeme tue He aS daté 25.03.2004.The sample points coordinates were fa 
mosaicked and an img extensioned raster grid DEM was 
created. 
The DEM used outside the Istanbul city boundry (2157km2) 
was produced by General Command of Mapping of Turkey. 
The ArcINFO Export e00 extensioned file(YÜKPAF-25) was 
converted to coverage format and united.Then a img 
extensioned raster grid DEM with a 1/25000 scale precision 
was produced from this data. 
Reference Map Data: 
Dgn extensioned 1/1000 scaled topographic maps within the 
Istanbul Metropolitan X Municipality duty — area(1850 
km?),which is in the boundry of Istanbul city,were converted 
to shp format according to the IKONOS imagery strip areas. 
Sis extensioned and 1/5000 scaled orthophotos were 
converted to img format and then mosaicked in the rest of the 
areas within the boundry of Istanbul city. Tif extensioned 
1/25000 scaled raster maps that were taken from the General 
Command of Mapping of Turkey archive were converted to 
img format outside the boundry of Istanbul(2157km?). 
Ortho-IKONOS product obtained after rectification: 
Using the map data mentioned above, IKONOS HDD(PO ID) 
strips with approximately 350 km? areas were orthorectified 
within the 7500 km? project area. Associate points both on 
the image and topographic map were found and selected. For 
each orthorectification process approximately 22 reference 
points were collected. These points were selected from ways 
and low buildings. After the orthorectification process the 
precision found in the technical specification that was formed 
during the adjudication of the project was supplied. After the 
orthorectification process a t im RMS in the Istanbul city 
boundry and a c 5m RMS was obtained outside the city 
boundry. 
  
  
  
Figur2. Overlayed image of the orthorectified IKONOS image 
and topograhic map. 
   
determined by the help of a preinstalled IKONOS image on a 
notebook and the Erdas Imagine 8.6 software GPC Controller TI 
feature.Personnel went to collect the water samples at the 
: ; ; . os : st 
previous mentioned points before the acquistion time mn 
25.03.2004 11:16-11:17 (local time) and took the samples In 
during the acquisition time.The water samples were brought to e 
the laboratory of ISKI in 3 hours for the determination of the 32 ih 
water quality parameters. It 
3.2 Study Phases p 
a 
IKONOS imagery(Seperately recorded bands in Red,Green, Blue T 
and Near IR) was used in this study. To avoid spectral mixture, > 
the part containing water was cut out of the image according = 
SQ 
to the maximum water elevation boundry of the lake. The image 
that was cut out of the original image was classified with the 
unsupervised classification method. 
PRC 
Fle Edt Hep 
wx 
Ga [A Layer Number 
Row Histonraen Color 
Ü 
  
"à ce 
4 
  
   
Figure-3 The thematic map of B.Çekmece lake obtained by 
unsupervised classification showing change in water 
(Total study area:2753.63 hectares) 
The red areas show the high TSM concentration while the 
purple areas show low TSM concentration. With the help of 
field study ISKI Map Department has found that there are 4 
main stream branches that flow into the lake in the study area.In ' 
addition to this, 2 main stream branches not decsribed as stream 
main branches according to the 20/02/2003 dated ISKI 
catchment areas protection and control regulation were taken 
into consideration as main stream branches after understanding 
from the thematic map (Produced from IKONOS imagery) that 
these 2 were causing the pollution in the lake. 
It was seen that the 5 and 6 numbered streams carried higher 
TSM concentrations to the lake than the other streams that 
were taken into consideration. With the help of the examinations | 
it was seen that when comparing with other streams, the 5 and 6 
numbered streams were not under protection and the 4 
  
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