358 
because of 
ding connected with the security against distortions, 
aircraft orientation changings. 
As ground system a compatible PC 386 with a high 
grafic display is used to read the flight data, for 
and first interpretations. 
The processing contains the correction of aircraft 
changes with the help of the recorded orientation 
images in the visible range are also used for rectification 
for cartographic calibration of the TIR-images. Therefore it 
necessary to read the visible images into the computer, 
photographic images of the airborne photocamera can be read 
means of an A4-scanner and the camcorder-data can be read by 
frame-grabber-board. 
The rectificated TIR-images are then processed with image- 
restauration-algorithms to improve the SNR in the images. This 
means the use of filters for removal of systematical errors, edge 
detection and smoothing algorithms. 
Booth the rough images and the resulting images are transmitted 
to the central VAX 11/785 station of the institute for archiving. 
There the data access for other institutions is possible. 
resolution 
processing 
orientation 
data. The 
and 
is 
The 
by 
a 
6. Image data processing 
During the forward movement of the aircraft there occur changes 
of the platform attitude. They can be resolved into roll, pitch 
and yaw. This leads to geometrical distortions in the scanned 
images. These distortions may be corrected with the help of the 
orientation data of the aircraft. 
In ref./6/ a method is described , which permits to make the 
geometrical corrections in real-time already on the aircraft. But 
it will be used only in future flights. This method bases on a 
variation of the cycle-time of the scanner which depends on the 
angular velocity of the aircraft. A necessary precondition for 
realisation of this method is a very fast signal processing. Cur 
rent TIR-data are geometrically corrected on ground by means of 
the recorded orientation data. 
Fig. 7 shows, how the atmosphere influences the measured radia 
tion compared with the original values on the earth.. There is the 
self-radiation of the atmosphere and the radiation of the back 
ground, which overlays the radiation of the source. On the other 
side one part of the radiation of the source is scattered and 
absorbed by' the atmosphere and so it cannot be measured by the 
scanner. During the first flights the temperature was measured on 
the earth and in the air and also the humidity of the air paral 
lel to the line of the aircraft. The aircraft was also flying in 
two different heights (500m and 1000m). With these comperative 
values it is possible to correct the atmospheric distortions. In 
the DLR (Deutsche Forschungs- und Versuchsanstalt fuer Luft- und 
Raumfahrt) programs are developed, which allow more exactly 
radiometric corrections /7/. These programs will be used in the 
future to correct the TIR-data.