PHOTOGRAMMETRIC ENGINEERING
/ OH
OH, H,0
Fıc. 1
ox” H, ©
§ Az
9, A" 5
T Oo A, sut 2 Qo
B, B
FIG. 2
The triangulation on the stereoplotting ma-
chine proceeds in the same manner as the
classical (coordinates) method, with the ex-
ception that the absolute orientation of the
first model is not necessary. For instance, the
triangulation could be carried on with the
first photograph horizontal. The strip adjust-
ment takes into account the effects of neglect-
ing the absolute orientation of the first model,
as will be shown later. From the machine co-
ordinates and elevations of the critical points
(the end points of the cross-bases and the
points known in elevation) the following ele-
ments (quasi-observations) could be deter-
mined for each cross-base: Its length L,, its
azimuth À, and its lateral tilt Q,. These val-
ues, when compared with the terrestrially de-
termined ones, will give us the following er-
rors in the quasi-observations for each cross-
base:
= Scale Error
AA = A; — A = Azimuth Error = A0
AQ = Q — Q = Lateral Tilt Error
If the determined elevations of the control
points permit determining the longitudinal
tilt at both ends of the strip (as in Figure 2),
the error in ® will also be available. (In such
a case, ® would be our fourth quasi-observa-
tion.) If this is not the case (see Figure 1), we
just determine the errors in absolute heights.
In this case:
AH = H, — H = Error in absolute height.
The theoretical and practical investigations
carried out by the author* show clearly that
the greatest part of the effect of the system-
atic as well as of the accidental errors seems
to be systematic. This important fact permits
* See Bibliography (3).
drawing the diagrams in Figure 3 and to de-
duce the given relationships.
Once the elements of the quasi-observations
are determined, the adjustment of the strip is
carried out very easily with the aid of the
simple formulae that are deduced by superpo-
sition of the effect of the different quasi-ob-
servations on the coordinates and elevation of
any point P (Y, Yp Kp).
In case of aerial polygon, the adjustment
formulae are as follows:
; ( oS dx? dxo . dAx dAx?
X - dSo — "mm of + _ -
| 2 2 2 12
do? d$»: d^
2 7 12 |
dxo: d Ax L dAx? dóo: d^ : i
2b 4b 2b 26)
d^ 2 1 /
6b? 6R? )
AX, =
ly? 0S
edil | x}
— ——
(2b
724 dAx?
i 6b?
( dAx )
hy FE Yi
| b
1Ax
2) : y + Y1idS, — 5S!
LU
; y? \ dAx dAw /
E 27 |
— dxo!
AY, = X{dwo} + X
= 105)
( b i)
“ZdSy — 55)} + X 8S — dd»
viz Eden — dan}
|
{ Inall the diagrams and formulae, b is the mean
base length, Z is the mean flight-height above
ground. The elements of orientation are given in
the symbols normally used. R is the earth radius.
