Expressed in millimetres at map scale, the permissible standard 
error m, for the contour height for the German Base Map is given by the 
formula: 
_ 0.4 + 3 tanß 
5 m 
where 
he s ard errors in Table VII, expressed in millimetres at 
map scale o 0, are shown in Fig. 9 together with the quoted German 
Base Map tol es. We are assuming that the accuracy specification for 
contour line translated into the scale of a given map remains the same 
for maps of the same scale range, i.e. large scale maps, medium scale maps, 
etc. Under + conditi n, direct comparison of contour accuracy of maps 
at differing scales is possible. 
conclusions can be drawn from the experimental 
The contour lines derived fromthe height data compiled on the Zeiss- 
Jena Topocart/ürthophot, Gestalt Photo Mapper II and Wild PPO-8 are 
1 within the tolerances used for the German Base Map with the 
flat is for the GPM II. The results are approaching 
ed by conventional contouring done on photogram- 
[he results obtained for the Zeiss-Jena instrument 
y goodand practically identical to the primary height 
information ted in Table VI. One should note, however, that the 
profile density was higher than for other instruments (4 mm profile 
interval) and extreme care was taken in the profiling operation, 
e 7 hours reported for scanning time (Table VIII). 
  
which is uM MET 
The contours derived from the Gestalt Photo Mapper II information are 
affected by clumps of trees or buildings. Systematic errors occurred 
up to 10 m distance (1 mm in the original photographs) from such 
terrain features. Point elevations in these areas should not be used 
in practical projects and these points were excluded from the results 
in Table VII and Fig. 9. 
A11 ortho photo conto irs submitted, when derived from sufficiently dense 
data, provide satis factory accuracy in steeper terrain. 
No significant dif! nce in accuracy was found for the contour lines 
derived f ‘rom t : fes h K320 profiles (10 mm slit) using profile points 
spaced at 4.8 mm and 9.6 mm along the scanned profile. The 10 mm 
distance between thes profiles is too large to meet the German Base 
Map requirements for the 4x enlargement factor which was used.