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Also this restructurization is conditioned by many factors, as psychological 
ones and object-characteristics as well. Psychologists formulated different 
laws of this "primary organisation" (H.VAN DEN BOSCH, 1977) or "Gestalt-laws" 
(K.KOFFKA 1935, R.W.KATES 1970, PRAK 1973). Although all factors act simulta- 
neously these laws try to describe separate aspects. A review illustrated 
by some examples in image interpretation will demonstrate their importance. 
1. Law of the integrated perception (law of Prágnanz) : separate visual sen- 
sations are integrated and percieved as one whole. Many conditions determine 
what and how this integration is done. Once integrated, image differentiation 
and recognition will follow. Consequentely, the adjustement of the image for- 
mat and size to the field of view is important to have optimal observation 
and analysis conditions (P.MEIENBERG 1966). 
  
2. Law of the image completion (law of continuity). Our visual perception 
has the ability of recognizing objects even when we can percieve only some 
parts of them. This ability is a great help to image interpretation and in some 
cases,as for instance aerial-archeological reconnaissance, it is even vital to 
detect the objects of interest. On the other hand, image completion, influenced 
by the other Gestalt-laws, may result in the "building" of non-existing features 
from a misinterpretation of the parts percieved. 
  
3. Law of similarity : features with similar shapes are differentiated first. 
Field patterns, for example, can be classified easily through visual image 
interpretation. Drainage pattern recognition is another example. 
4. Law of neigbourhood : patterns of similar shapes are differentiated more 
easily when the elements are localized near to each other. The result is 
that the individual elements are no longer discriminated, but only their 
Gestalt-properties are recognized. Field pattern recognition is again a good 
example. Texture-description in photo-interpretation is entirely based upon this 
phenomenon. 
  
5. Law of the primitive shapes : complex shapes are reduced to one or a few 
primitive shapes which are simple and mostly geometric : figures as lines, 
Squares, rectangles, circles, and so on. This aspect is important for the image 
completion, because the mind will use first regular, geometric lines and shapes. 
  
6. The reversible perspective : our visual perception normally works stereos- 
copically and the distinction between a "foreground" and "background" is 
a natural capability. A coherent, compact object will be differentiated from 
its background, which will be thought of as contineous behind the object. 
This is due to the image completion and works perfectly with the stereoscopic 
analysis. No errors or doubt occur the differentiation between foreground and 
background. Nevertheless, with monoscopic visual interpretation, as done for 
example upon satellite imagery, especially when outside our visual spectral 
experience, the determination of the foreground and background is not that 
easily. Difficulties occur mainly in the visual description and classification 
of textures. When doubt exists, we use associations we experienced already with 
our daily stereoscopic perception : blue is far away, red is near ; high con- 
trast is associated with foreground, low contrast with background ; coarse 
textures are experienced to be closer to our eyes than fine textures. 
Observationsduring student's excercises showed that some of the troubles in 
stereovision could be related to the disconcordancy between the observed 
image characteristics (colour, texture) and the expectations based upon previous 
visual experiences. When some doubt exists, another capability of our visual 
perception starts acting : the reversible perspective. All foreground-background 
combinations are tested in order to find, to our experience, an.acceptable one. 
When this seems not to be possible this image will be refused, and consequente- 
ly it will not be differentiated from the Gestalt. This process of reversible 
  
  
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