LINEAR is the most optimistic (see Tables 6 and 7). Percent 
differences for long profiles are within + 34% except with program 
LINEAR. 
For short profiles RF is the most conservative while LINEAR is the 
most optimistic (see Tables 6 and 7). All programs have percent 
differences exceeding +50%. 
For the Raymond profiles of varying sample spacings, LOGKV and RF have 
no increasing trends in percent differences (see Table 6). RF is the 
most conservative, while LINEAR is the most optimistic. Percent 
differences are within + 40%. 
For the Crowsnest Pass profiles of varying sample spacings, all 
Programs have increasing trends in percent differences (see Table 7). 
LOGKV is the most conservative, while SPECTRA is the most optimistic. 
Only program RF has percent differnces within + 33%. 
6. RECOMMENDATIONS 
Based upon the results of relative and absolute comparisons, the most 
suitable  program(s) is/are recommended for each sample profile 
depending on its roughness, length and sampling rate (see Table 8) as 
follows: 
a) Roughness 
- rough (R.F. 257) 
- flat (R.F. <5%) 
Length 
- long (length >1.75 model base) 
- short (length < 1.75 model base) 
c) Sampling rate 
= high (Ad <1.0mm at image scale) 
- low (Ad >1.0mm at image scale) 
The recommended programs are based upon percent differences within 
+50% obtained from the tables referenced and profiles used. If more 
than one program is recommended, the programs are arranged in 
increasing degree of optimism. In other words, the first program is 
the most conservative, while the last is the most optimistic based 
upon their means of percent differences for more than one profile. In 
case of contradiction between relative and absolute comparisons the 
latter prevails. There were no data for (c) and (8). 
It can be noted that short profiles can be used only if they are rough 
and of high sampling rate. For more reliable result, the sample 
profile shall be as long and of high sampling rate as possible, and 
shall be truly representative of the model's roughness. 
ACKNOWLEDGEMENTS 
The following companies are gratefully acknowledged for supplying the 
data under contracts, used in this paper: 
a) Terrain Aerial Surveys Ltd, Edmonton, Alberta for measuring 
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— Tm