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Band Contents 
No. 
1-10 [Multispectral bands 1 - 10 
11 Calibrated thermal infrared data of the midday flight 
12 Calibrated thermal infrared data of the evening flight 
13 Calibrated thermal infrared data of the morning flight 
14 Difference of temperature values between evening flight 
and morning flight 
15 Vegetation index NDVI calculated from bands 5 and 7 
  
  
Table 3: Chosen Bands of the Multispectral and Multitemporal Data 
Composition 
3.6 Investigation of Band Correlations 
  
Correlations for each band combination are calculated for 
the three flight areas and for certain sites. Table 4 gives the 
the general results. 
  
  
  
  
  
  
  
  
  
Correlation? | Band combination 
”> 0,95 1-2,2-3,3-4,3-5,4-5,7-8 
095»52»0,90]1-3,2-4,2-5 
09»2»0,85 |1-4,1-5,3-6,4-6,4-10,5-6,5-10,6-9, 
9-10 
0>r2>-0,5 3715,6-15,10- 15, 11 - 15,12-15,13-15 
-0,5> 1-15,2-15,4-15,5-15 
  
Table 4: Correlation r? of certain Band Combinations out of the 
15-band Total Data Set (description of bands see Tab. 3) 
The following conclusions can be made: 
The band combinations 1 - 2, 4 - 5 and 7 - 8 highly 
correlate. Information on bands 1, 4, and 8 are mostly 
included in the bands 2, 5, and 7. It is no coincidence that 
the spectral areas covered by these bands are not used by 
Landsat-TM, so these bands can be ignored in 
multispectral classifications without a serious loss of 
information. 
Very little correlation values can be registered in any 
combinations with band 15, (vegetation index NDVI). 
Negative correlation can be explained regarding the 
calculation formula of NDVI. Only in combination with 
bands 8 and 7 there is a positive correlation of band 15. 
4. ANALYSIS OF DATA FOR SOIL SEALING 
IN URBAN AREAS 
4.1 Registration Problems of Soil Sealing Degrees using 
Aerial Photos and Scanner Data 
Problems occur if items are covered or hidden (trees, 
underground car parks and planted greenery on roofs): 
There is no other way for all remote sensing techniques 
than looking down to earth's surface. In the case of passive 
Optical sensors there is no chance to look through the 
Upper surface material, so everything underneath is not 
489 
recorded. As a consequence soil sealing under leaved 
trees can not be detected. Only with visual interpretation of 
the surroundings or with additional expert knowledge these 
areas can be identified. 
Furthermore sealed soil of underground car parks, whose 
surfaces are covered with vegetation, or planted greenery 
on roofs can not be registered with remote sensing 
techniques. This is a specific problem of city centres and 
new residential parks where these kinds of surfaces cover 
up to 15 % of the total areas. 
Precision of soil sealing degree values derived from remote 
sensing data: 
Remote sensing methods can hardly deliver the same 
exact values as a terrestrial investigation. 
This includes the geometric precision as well as the 
contential precision. Although there are a lot of defined 
indices to describe soil sealing the "soil sealing degree" is 
the best index reproduced by remote sensing techniques, 
because it does not pay much attention to surface material. 
Other indices, e. g. the "soil function index", which is more 
sensitive to drain capacity can hardly be reproduced when 
using remote sensing data. It can only be derived if 
correlated with the soil sealing degree. Even with the 
highest geometric resolution small pavement areas or joints 
are not recordable. 
Rectification of Scanner Data: 
The rectification of scanner data is a very time consuming 
and costly task. A large number of ground control points 
has to be found manually (without automation) and the 
actual rectification done by a special and expensive 
software. The costs of data rectification are estimated 2 - 3 
times higher than the costs of data acquisition. Possibly by 
means of very high resolution and precise GPS navigation 
instruments such high costs could be reduced decisively. 
This latest technique enables to rectify automatically 
knowing the precise aircraft position during the whole flight. 
Such increasing efficiency would make the use of scanner 
data much more attractive to answer various scientific 
questions. 
Panoramic Distortion by Wide Scan Angle: 
The scan angle can reach a maximum of 43° declination 
from Nadir. This fact causes immense distortions in 
peripherical zones of scanner stripes, large shaded areas 
and blind spots, as well as the reproduction of vertical 
surfaces, e.g. house walls. To reduce this effect the wide 
side overlap of 40 % is chosen and only the central area of 
a stripe with its small distortion is then taken at the expense 
of a more costly acquisition and analysis. 
4.2 Vegetation Index as an Instrument to identify Soil 
Sealing 
The vegetation index gives an very precise overview, 
where earth surfaces are covered with vegetation. 
For a multistep analysis strategy the vegetation index NDVI 
should only be used to separate areas which are covered 
by vegetation and therefore unsealed (wrong interpretation 
of underground car parks with plants on surfaces and 
planted greenery on roofs are inevitable). 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996