! 2004 
rule of 
on the 
is size 
n like 
get the 
1 
  
  
LL] 
  
  
such a 
dividual 
e range 
nes and 
a much 
yn roads 
2 pixels 
is also 
colour 
complex 
ip scale. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
  
  
  
  
Figure 5: IKONOS pan 
size of element on road: 2 x 3 
pixels 
  
Figure 6: IKONOS pan: size 
of road separation lines 
0.2 pixels 
  
  
  
  
In figure 4, upper right, in the multispectral IKONOS image 
with 4m ground pixel size, buildings with a red roof can be 
identified even if they do have only a size of 2 x 2 pixels. The 
neighbourhood of the buildings do allow also a save 
interpretation. Without the support by the colour the 
identification of the buildings is quite more difficult. In figure 
4, lower right, the multispectral IKONOS image has been 
changed to grey values. In this image the detection and 
interpretation of single buildings is quite limited and needs a 
size of 5 pixels. 
     
  
  
  
IRS-1C 
Figure 7: streets in urban areas 
  
examples in figure 8 do show very clear the difference between 
detection and interpretation — if we do have the information 
about the location of a road from the SPOT image, we can see it 
also in the IRS-1C image. The visible fractions of the road can 
be connected if we do have some information about the 
location. 
   
IRS-1C 
Figure 8: roads in rural areas 
  
  
SPOT 5 
  
  
  
Topographic maps with smaller scale do not show individual 
buildings, only building blocks or even only the build up area. 
The identification of the build up area is not a problem with all 
used space images. The identification of building blocks even 
can be made with ASTER images having 15m ground pixel 
size. 
The identification of the road network is very important for 
topographic maps in the scale range of approximately 1:50000. 
As obvious in figure 3, in the ASTER and the TK350 images 
the major roads can be identified but not the minor roads. This 
is quite different in the images starting with IRS-1C and smaller 
pixels. In the build up areas in IRS-1C images not in any case 
the streets can be seen, but the structure of buildings includes 
the information of a street between two lines of buildings 
(figure 7 left). The slightly smaller pixel size and better image 
quality of SPOT 5 (figure 7 right) shows quite better the details 
of the street network. 
In rural areas not 10096 of the roads could be identified in the 
IRS-1C image (figure 8, left). Here we do not have major 
problems with SPOT 5 (figure 8, right). On the other hand, the 
  
  
Of course with the better resolution of IKONOS and KVR1000 
there are no problems with the identification of the minor road 
network. The IKONOS images are always in the range of a 
competition with aerial images. Standard aerial images do have 
a photographic resolution of approximately 40 line pairs/mm. 
Based on experiences this can be compared with 80 pixels/mm 
or 12pm pixel size in the image. Corresponding to this a ground 
pixel size of 1m is available in aerial images with a scale | : 80 
000, or QuickBird images do correspond to a scale of the aerial 
photos of 1 : 50 000. 
  
  
Figure 9: water courses in 
near infrared band of 
ASTER 
  
  
  
In the test area Zonguldak not so many smaller water courses 
are available. For the mapping of water courses the spectral 
range is very important. In the near infrared band, there is 
nearly no reflection of the energy from the water bodies, that 
means, the water courses are black and do have a very good 
contrast to the neighbourhood (figure 9). 
In Wegmann et al 1999 the information contents of an IRS-1C 
image has been compared with aerial photos 1 : 12 000. The sun 
elevation of the used space image was very low, so the quality 
was not so good like in the area of Zonguldak. In the IRS-1C 
image 56% of the road length was recognised and correctly 
classified. 9% has been classified as path and not as road, so 
finally 35% could not be seen. A higher percentage of the not 
visible roads by error were just identified as field separation. A 
smaller percentage was covered by trees in a forest. By this 
reason also in the large scale aerial images 6% of the road 
length could not be seen. 5% was classified as path. Compared