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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
4. CASE STUDY 
During the fast increase of water elevation in the river Waal at 
the location Nieuwaal, Bommelerwaard (Fig. 5), on January 
1995, TIR images and normal colour images which were 
prepared by Directie Noordzee (Ministry of public work- 
department North Sea) has been taken to the Meetkundige 
Dienst (Survey department). This office does the image 
processing. 
Before the actual processing of the images can be started, the 
data is saved digitally in a workstation at the Meetkundige 
Dienst. And after that further changes with image program 
"ERDAS- Imagine" are possible. 
The next step is the geometrically correction of the data because 
the planes have irregular movements during the flight. This 
implies that the data is transformed to a co-ordinate system. 
The resulted data will be matched with an other geographic 
information system. Correcting aeroplane data geometrically is 
a time consuming business. 
After importing and geometrically correcting the data, the 
images are being analysed. Notice, the colour videotape that 
  
N 
A 
Highway 
N Railroad 
BH] River 
[] Town 
  
0 10 20 Kilometers 
  
  
  
Figure 5. The map of the Nieuwaal, Bommelerwaard 
(Netherlands) 
was taken from the crisis area, can be watched directly after the 
flight with the help of an S-VHS video recorder, because the 
video data is saved on S-VHS videotapes. This is fastest way to 
get at an actual and recognisable overview of the critical areas 
but that doesn't have clear information about seepage (Fig. 8). 
The TIR videotape can also be watched directly with an S-VHS 
video recorder, though the interpretation is somewhat more 
difficult. The images that you can see contain temperature 
difference depicted in grey colours, which make the landscape 
less easy to recognise (Fig. 6). 
The TIR images are adapted in such a way to show potential 
places of seepage (Fig. 6 and 7). Because when the temperature 
‘of the water is higher than the land's temperature, the water will 
be depicted white while the land is clearly identifiable in darker 
grey tints. 
381 
It has to be said that this method is only then useful, when a 
temperature difference between land and water exists. In figure 
7, the brightest areas in the down and middle of the picture 
show the water in the inner slope of dike (seepage). This water 
is warmer than soil (body of dike) and the water in the outer 
slope of the dike (water in the river, right side of the picture), so 
the seepage areas have the highest brightness in the picture. 
The body of dike is colder than the water in the inner slope and 
outer slope of dike, therefore it is shown with dark tone in the 
picture in compression with the other parts. The water in the 
river (in the outer slope of dike) is warmer than soil and colder 
than seepage (right side of picture); thus it is shown with lower 
brightness. 
With the help of digital image processing, these video and 
geometrically corrected TIR-strips of the same surroundings, 
were combined by Fraikin et al. (1995) (Fig. 9). This 
combination is based on the change of intensity of the video 
image to the intensity of the TIR record. In this way the colour 
and clarity of the original video image is stored but the contrast 
is determined by the TIR image. The result shows an image in 
which the qualities of video (overview and identification) are 
combined with the qualities of TIR images (reproduction of 
temperature differences, seepage). 
  
Figure 6. Geometrically corrected TIR image of the dike at 
Nieuwaal, Bommelerwaard (Fraikin et al., 1995)