matrices. Output is a maplike printout with symbols each meant 
to correspond to a given type of land use. 
EXIO This programme can produce a maplike printout of radiation classes 
within one spectral band, the upper and lower limits of which can 
be preset according to statistical information obtained by STATS. 
It also allows the mapping of classified results of arithmetical 
combinationssuch as interchannel radiance ratios. An object iden- 
tifiable in a given channel but whose radiance range overlaps with 
that of other objects in another channel can be separated first 
and the corresponding multispectral information can be masked i.e. 
rendered temporarily inaccessible to further classification. 
This then allows separations in the other channel that was pre- 
viously blurred by the overlap. 
4. Procedure 
Semi-automated mapping and surface assessment of selected land use cate- 
gories requires that on each separate CCT the specific spectral signatures 
of each category be known. These signatures can only be derived from the 
radiation in the various spectral bands reflected by homogeneous training 
areas the land use of which is known. It is therefore essential that 
pixels belonging to such training areas can be exactly located on topo- 
graphic maps or on cadastral plans, that line and element numbers of the 
pixels on the CCT can be translated in terms of latitude and longitude. 
4.1. Location of the test site on the CCT 
In a first approximation line and element numbers amply delimiting the 
area in which the test site was certainly located were roughly deduced 
by mensuration on the multispectral colour composite bearing the same 
identification number as the CCT. Of this area the video data were then 
transscribed into ORSER format (COETRAN or SUBTRAN programmes) and a map 
like printout was generated.(NMAPW programme) on which certain landmarks 
outside the test site such as major highway crossings, major agglomera- 
tions, forested areas with peculiar outlines, could be recognized. 
On this large printout, which for reasons of economy can eventually be 
produced in a reduced version (every nth pixel), the test site pixels can 
be more accurately situated. Further computer work was restricted to the 
test site area. Its form, rectangular on the printout, corresponds 
to a parallelogram on the man. For more accurate location of pixels, map- 
like printouts were generated for the channels providing the best con- 
trasts. 
For transitions between areas at least 3 (hor) by 2 (vert) pixels large 
(170 x 160 m) which in a given spectral band both appeared as relatively 
homogeneous, it was generally possible to prelocate the pixels within 
100 m on the 1/25.000 NGI topographic map while field checking often 
allowed an almost exact location. Intermediate pixels could then be 
positioned by interpolation. 
     
  
  
   
   
  
   
  
  
  
  
  
   
  
  
  
  
  
  
   
  
  
   
   
   
  
  
   
  
  
  
  
  
  
  
   
  
  
  
    
  
  
  
  
   
  
  
  
   
    
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