56 
Evidently the errors of the relative orientation of the individual 
models will become the main cause of the coordinate errors of the strip. 
The errors will be accumulated through the transfer points. 
We assume the photographs of the first model —1,0 to be fixed which 
means that the twelve elements of the external orientation of the photo- 
graphs —1,0 are known. The elements of the external orientation of 
each photograph in the triangulated strip will then be affected with 
errors with respect to the photographs —1,0 as a result of the accumula- 
tion of the errors from the triangulation. The sources of errors are 
primarily the accidental errors of the y-parallax corrections (measure- 
ments) and of the setting of the floating mark. 
3.1. The error accumulation formulae 
The basic error accumulation formulae for aerial triangulation were 
derived by BACHMANN 1946. The errors of the elements of the relative 
orientation of each photograph are denoted relative errors. These relative 
errors accumulate in the triangulation procedure. The accumulated 
errors of the elements of the external orientation of the photographs 
with respect to the elements of the first model (— 1,0) are denoted 
total errors. 
According to BACHMANN 1946 the basic error accumulation formulae 
of aerial triangulation are with minor changes of signs (fig. 8) 
i=n 
Dx, — X dx. (211) 
i-1 
Dy, = 3 dy, (212) 
i 1 
Da, == 2 do, (213) 
i=1 
Dby, =" +b In — t)dx, + 2X dby, (214) 
i=1 i=1 
Dbz, — — b X (n —i)dp, + X dbz. (215) 
i=1 i=1 
DX ; vn [^ p? \ b 1 
)X -b XY 31] T ; .-— 
" # |o he | h = 4) 4p, 
bh i=n b i=n : 
— À (2 n — 22 + 1) dbz. — X (n—35-F1)4H, , (216) 
b C à; b.