This is in relation with peculiar meteorological conditions : slight 
wind from the south-east competing with an inversion layer occuring at the level 
of 2500 feet. 
In the case of Brussels, the classification of the area extending 
westward of the Canal de Charleroi is bent by a haze layer brought in by industri- 
al smokes from estates established on the canal embankments. The existence of 
erratic patches of class 5 is remarkable in the whole area covering the western 
agglomerated townships (Anderlecht, Molenbeek St-Jean and Jette). The "dark" 
classes 1 and 2 characterizing high urban densities are shaded off by the layer 
contact. Thus this haze generates a quasi-homogeneous reflecting area on still 
very differenciated districts with regard to land use and housing. 
Also the wooded areas get hardly identified when covered by haze. 
On a digitalization of the Channel 7 data (infra-red) one could state that, in 
comparison to an identical but not "shaded" wood (mixed full-grown oaks and 
beeches in Laeken), the Laarbeekbos in Ganshoren, for instance, shows a higher 
reflectance (level : 1,21 against 1,01 to 1,11 for Laeken). This increase seems 
well to be the consequence of the haze layer self reflectance. Thus, we can 
conclude that it is not possible to apply to the whole urban image, the signifi- 
cant levels of classification worked out fort the non-shaded area. 
In Charleroi, the wreath of smoke shape might be worth studying : 
circular shapes where classes 19, 18 A, 18 B, 15 and 11 are centrifugally dis- 
tributed. More, as in Brussels, a haze seems to have changed the reflectances 
in the NW part of the urban area. 
Conclusions 
The proposed procedure of urban interpretation consists of 5 steps : 
1. Distinguish "families" of similar classes. 
2. By using pattern recognition, distinguish spatial organization of these 
families. 
3. Relate these patterns of values with objects or groups of objects, using 
maps, aerial photographs, ground-truthes. 
4. If families of clusters corresponding to dissimilar land wes are mixed, use 
the procedure of assisted classification 
5. Locate and delineate the corresponding land uses with the aid of an eventual 
geometric correction. 
      
   
   
  
   
   
   
   
   
   
   
     
  
  
  
  
   
   
   
   
  
  
   
   
   
     
  
  
  
  
  
  
  
  
  
  
  
  
    
1. The 
yields 
perimet 
industr 
classif 
2. This 
of hous 
pretati 
tructur 
So it w 
surface 
tíon in 
We hope 
to be ve 
cal int: 
process 
to the | 
3. At di 
the idei 
reflect: 
especial 
tructure 
sificat: