usands of
ld like to
otography
sults seem
mmetry is
lum errors
its length.
mation for
ra stations
varying in
hough the
rotational
f the strip,
/s of error
wever, the
onal para-
w the un-
mation of
o informa-
e result is
om 5 to 23
! a point in
lines show
nt situated
nt that the
rdinates is
le summa-
ied from a
reating the
rmore, the
that only
ent. There-
ANALYTICAL AERIAL TRIANGULATION, DISCUSSION 23
fore, the information represents, statistically
speaking, the optimum result obtainable by the
process of strip triangulation.
A A
A A
A A
A A
Fig. 4
It is now possible to study the question about
an optimum flying height for bridging a certain
distance between given control. In other words,
90 |
st=star ,
6Q.
S03 70 UTOR EUST
No of photographs in the strip
Fig. 5
it is possible to determine the optimum number
of photographs in a strip. Fig. 3 shows the
corresponding results. For the assumed 66%
overlap, a minimum for the mean errors of both
the X- and Z-coordinates is reached already
after 7 or 8 photographs, while the correspond-
ing minimum value for the Y-coordinate occurs
after about 12 photographs.
From these results one must conclude, that
extended photogrammetric multi-station trian-
gulations will not give satisfactory results if only
the principle of relative orientation is employed.
The optimum strip or block is shown in Fig. 4,
indicating that the optimum flying height must
be chosen in such a way that two or respectively
four adjacent but not overlapping photographs
cover the area between the given control data.
In order to assure the usefulness of aerial
110
mmis Ku M^ 1078 ÿ
ys m) 4
100 I yl l= Ky HM 10 iV
m, [ml=K, uM 107$ NÉ
H=Mean square error of unit weight ^
90) in microns 4 :
Mz X (scalefactor) X 4
80|
70]
60
50]
4Q|
30]
2.0]
T T TT T T T T T T T
9 1 13 15 17 19 23
No. of photographs in the strip
Fig. 6
triangulation for more extended strips or blocks,
it is obviously necessary to incorporate such
auxiliary data which will influence favorably the
aforementioned double summation of errors in
the translatory components.
Fig. 5 shows the influence of additional
celestial data. Assuming auxiliary star photog-
raphy (9 evenly distributed stars) at each station,
the error propagation curves indexed “st” were
obtained, and correspondingly, the curves in-
dexed by "s" were computed, assuming auxiliary
sun photography at each station. The result
shows that additional astronomical information
helps considerably in reducing the mean errors
of the Y- and Z-coordinátes, but cannot do any
good with respect to scale, (X-coordinate). This
obviously is explained by the fact that the sun
and stars are essentially in infinity.
Fig. 6 shows the error propagation, assuming
