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Software 
Performance and operational characteristics can be enhanced by in- 
cluding manual grid densification during PS [4], by allowing a vari- 
able threshold to adapt PS better to terrain roughness and vegeta- 
tion coverage,and by providing an interrupt option for breaks and 
on-line graphic display. 
Gross error detection after each sampling run would allow direct 
remeasuring and prevent adulterations in data analysis. In addition, 
on-line verification of data would increase the operator's involve- 
ment in the process, and instrument time would be shortened. 
  
REFERENCES 
E Makarovic, B. Progressive sampling for DTMs. 
ITC Journal, 1973-4 
[2] Makarovic, B. Amended strategy for progressive sampling. 
I7C. Journal, 1975-1 
[3] Makarovie, B. Composite sampling for DTMs. 
ITC Journal, 1977-3 
[4] Makarovic, B. From progressive to composite sampling for 
DTMs. 
Geo-Processing, 1 (1979) 
[5] Singh, Y.P. Performance evaluation of composite sampling 
for DTMs. 
M.Sc. Thesis, ITC, 1981