To see how the spectral separation line coincides with the spatial 
boundary between urban and rural, additional grey scales might be 
introduced for pixels close to the separation line. The result is 
shown in Fig. 4. 
Pixels close to the separation line do indeed form 'fringe rings' 
around the urban area, as could be expected, since on the rural/urban 
boundary there will be many 'mixed' pixels. But close to the separa- 
tion line there are also pixels belonging to the upper parts of the 
agricultural and forest clusters, so that scattered parts of the 
rural areas are now also shown on the maps that do not belong to the 
urban fringe at all. 
5. Comparison USEMAP — LANDSAT 
5.1 General 
When comparing the USEMAP results with the LANDSAT urban area, it is 
important to realize the differences between the 2 sources, They are 
summarized in the table below. 
TABLE 2: Specifications of USEMAP and LANDSAT classifications 
  
  
USEMAP LANDSAT 
Date Oct. 1972 March 1973 
Scale 1:10,000 - 
Gridcell 50x83 m2 57x77 m2 
Pixel (3x3 m2") 57x77 m2 
Classification 65 classes 2 classes 
Time 40 man-days 1-2 man-days 
Area 4000 ha 6000 ha