TABIE 4 
  
ERROR TOLERANCES FOR ANALOG BRIDGING 
  
Fraction of 3.46" (88 mm) | 6.0" (153 mm)| 8.25" (210 mm) 
Photography Scale Z X & Y Z X & Y Z 
  
  
For 90% of Points 
(1) 1:860 1:700 1:500 1:500 1:360 
(2) 1:35,000|1:28,000| 1:20,000|1:20,000|1:15,000 
  
For Remaining 10% : 
of Points  (1)]|l: 1:530 1:350 1:250 1:250 1:180 
(2) |1: 1:17,000|1:14,000|1:10,000|1:10,000|1:17,000 
  
  
  
  
  
  
  
  
  
When aerial analytical triangulation methods are employed, the 
acceptable error tolerances are usually expressed as a fraction of the 
aircraft flight height above the ground at the instant the photographic 
exposures were made. Generally, there is a range within which accu- 
racies will be acceptable according to the engineering stage or the 
character and density of ground cover. Accordingly, subsequent tabu- 
lation, Table 5, summarizes error tolerances for aerial analytical tri- 
angulation in terms of the maximum error allowable, the average 
(arithmetic mean) error, and root mean square error. ‘The users of 
aerial surveys, of course, have the alternative of requiring accuracies 
different from those given in the tabulation, either to achieve greater 
precision or less precision according to need and expected costs of 
accomplishment. 
TABLE 5 
  
ERROR TOLERANCES FOR AERIAL ANALYTICAL TRIANGULATION 
  
Absolute Error as a Fraction of Flight Height 
Error Tolerance Horizontal Position Elevation 
Classification X Z 
  
  
T 
  
S 
ce 
es 
bt pd 
Hb 
O vn Co 
"e 
^e 
Maximum (1) 
(plus or minus) (2) 
fp 
2 fo fo 
e u 6 
D =~ 
O 
Ó 
HER 
= NN 
w ee % 
888 
3 
  
^e 
Q 
© 
© 
oe 
ppp 
Ww 
o 
8 
o 
35888 
Average ( 
(arithmetic mean) ( 
*e 
Q & œ 
w 
w 
FRE 
Hp 
O4 
Ww eo 
88 
bp 
HEHE 
LÀ 
  
Root Mean Square ( 
( 
( 
® ee 
.. 
HR 
IN 
e 
28 
*e 
1 
2 
3 
1) 
2) 
(3) 
1) 
2) 
3) 
x 
REN 
REN 
ROS EE 
MJ 
88818 
vw 
© 
© 
© 
w