:SSION 
LAND 
uplands. See Legend for areal distribution. 
(3) The detail of mapping of the floodplains in the ground truth map could not be matched 
by the digite! classification. On the other hand, the uplands were not mapped beyond the litho- 
logical difterentiation on the GI map simply because of time and cost, whereas the computer 
went into such detailed differentiation of refiectance classes of these large terrain units that 
would have taken months ot photo interpretation and field work to accomplish if done by con- 
ventional means (api * field work). Fig. 3. 
  
  
Fig. 3. Ground Truth map by aerial photo interpretation and field work. Note 
the detailed mapping in floodplains and sand islands and the demarcation of 
the major landforms and geological units but little or no subdivision of the