averse, levels or by 
xamination before 
examination after 
a qualitative and 
lank areas. 
lotting for the 1: 
ing only in areas 
heavy shadows in 
Cadastral Service 
fterwards qualita- 
completion before 
uls and toponymy 
s for the National 
naps of N. Africa 
,000 maps of the 
published without 
veys mady by the 
y of Lake Tchad. 
se the slopes were 
100,000 based on 
I different simple 
at the most rapid 
| which the prints 
te obsolute orien- 
eights were then 
> others by plane- 
‘ield work on for 
les. The Swedish 
1g. 
ed either method. 
ete advance field 
phes has permit- 
in the office on 
ompletion which 
ory, but depend- 
completion after 
ap. 
ym the National 
the case of the 
(359) 
German, Canadian, and Finnish Reports. The Swedish report gave only the 
planimetric errors determined in two controlled areas of the Economic 1: 
: 10,000 photo map; + 7 and + 9 meters. Are these mean or maximum errors? 
The USA report states only that the errors comply with or are less than 
those fixed by the National Standards of Map Accuracy. 
The Netherlands Report gave as results obtained: X and Y —0.2 mm at 
the scale of plotting Z equals 50 or 60 centimeters on the ground. These refer 
to tolerances for 1:10,000 maps from 1 : 20,000 negatives. 
The Belgian Report states that the Ministry of Public Works satisfies the 
required conditions; the IGM indicates for 1: 25,000 map 0.50 meters on refer- 
ence points 0.8 meters on average ground. These refer without doubt (but not 
precisely) to mean errors. 
Austria indicates for 1:25,000 maps, (plotting at 1:10,000 or 1:12,500) 
the residual errors on 100 models including 750 control points, mean errors of 
+ 1 m in altitude and + 2 m in planimetry. The scale of the negatives was not 
given. They refer to the results obtained on stereoplanigraphs. Tests on the 
ground before 1950 on multiplex surveys gave + 8 m in altitude of contours 
and — 7 m in planimetry. 
The Swiss report indicates a theoretical mean square error in altitude of 
+ 0.25:1000 of flying height, in planimetry 0.28:1000 flying height. The 
practical values obtained are given in percentages of these tolerances 30 to 80% 
for planimetry; 90 to 100% for altimetry but these tolerances are not precise. 
The Italian Report gave very detailed notes on the results obtained. For 
the 1:25,000 IGM surveys, planimetric errors are within errors of graphic 
measurements, for heights + 1 m (mean error?). The operators errors only are 
stated as less than 2/100 mm at the scale of the stereoscopic images. In a 1 : 2,000 
survey made by the E.LR.A. the ground tests gave mean errors 0.42 m in pla- 
nimetry and of 0.25 m in altitude in points measured by the apparatus and 
0.90 m for contours but the scale of the negatives used was not given. 
At the Italian Cadastral Service the precision obtained is always better 
than the tolerances set in the cadastral Record Books. These tolerances are set 
by formula for the planimetry and for the differences between the profiles 
drawn from the maps and the true profiles. The differences remain less than 
2 mat 1:2,000 and 4 m at 1:4,000 for slopes not exceeding 25 grades (22*/2 
degrees). 
The practical precision obtained from the Nistri Multiplx as given as + 
0.1 mm in position == 0.3 mm in altitude on the scale of the stereoscopic image 
(maximum Or mean errors?) 
In France the IGN, the theoretical precision resulting from the residual 
errors on the ground control after absolute orientation are as follows for stereo- 
topographes A.B. and C. at the scale of the stereoscopic image, mean errors = 
2/100 mm, maximum errors == 5/100 mm. 
For the 1/20,000 map of France according to whether the stereoscopic 
image is 1: 10,000 or 1 : 20,000 one obtains mean errors of == 0.30 mm == 0.60 
and maximum errors of == 0.30 m - 0.60 and maximum errors of = 0.50 and 
zn 
For the 1:50,000 map of North Africa the stereoscopic image is 1 : 40,000 
the residual errors on control points are 0.8 mean and + 2 m maximum. 
For the 1:100,000 map of the territories the mean residual errors are 
28