strips
ps had
d also.
eading
ites of
'ontrol
and in
points
' adju-
s been
lready
gram.
ineous
sock on
ontrol
points
of two
astern
rthern
points
| 18 to
21 will
ngress
lable.
second
mplo-
ans of
rners:
ogram
yy the
ffered
photo-
deve-
fered
of 90
graph
. Spe-
bs had
nearly the same value and furthermore, that the photos of adjacent strips had a good
junction. In this we did not always succeed. The number of pictures within one strip
varies between 15 and 18.
3. — Only some of the control points could be used as pass points for the three
lateral strips. Therefore additional pass points were required from the I.G.N. These
additional points were photogrammetrically determined by the I.G.N. and delivered
by the end of April 1960. Their accuracy relative to x and y was indicated to be 1,5
m, and relative to z — 0,5 m. For the present purpose this accuracy will be absolutely
sufficient. In the beginning it would be satisfying to know the planimetric position
and elevation of 4 pass points each in the initial stereoscopic model, and of 2 pass points
each in the terminal stereoscopic model, as well as an additional spot elevation in the
middle of each strip. However, in order to test a new method of calculation and to have
an absolute orientation of the lateral strips, finally 4 pass points each were required
in the initial and in the terminal stereoscopic models, so that the absolute orientation
of these stereoscopic models is fixed. In order to have an adequate orientation in the
middle of the strips, 2 or 3 additional pass points were required, so that finally a total
of 33 pass points are at our disposal.
4. — During the flight a plate of plexiglass was placed in front of the lens. In
order to determine, beside the effects of earth curvature and refraction, also the in-
fluence of this plexiglass plate the stereoscopic model 556-560 situated in one corner
was used as test model. The base lengths being different within the strips, the stereo-
scopic model 557-560 was additionally used, and, first the coordinates of 11 points
were selected for comparison. The minor accuracy of levelling resulted from several
orientations and amounted to 0,5 m. Unfortunately we found residual parallaxes
amounting to nearly 0,1 mm. The distribution of control points being unfavourable,
the influence of the plexiglass plate could not yet be determined unequivocally. Threre-
fore, pursuant to the proposal of Dr. Brucklacher who repeated the measurements, 7
additional spot elevations were required for the stereoscopic test model. The I.G.N.
also kindly provided these data towards the end of June 1960.
5. — The statoscope failed during the flight. Therefore we had to do without
the statoscope records during our measurements. Perhaps we shall try later to intro-
duce the statoscope records, available for the other cameras, into the adjustment with
minor weight in order to avoid heavy bows (deformations) of the flight strips.
6. — The spaces between fiducial marks of all diapositives were measured in
order to adjust or to eliminate later deviations by means of a focal distance accordin-
gly modified. After all, the differences shown by the different pictures within one di-
rection amounted up to nearly 0,2 mm. The differences between the two coordinate
directions are about 0,1 mm. Major deviations (up to 0,4 mm) occur in the 3rd lateral
strip. This is due to the fact that most of the diapositives of the first shipment were
broken, so that it may be assumed that the original films have been subject to changes
in the meantime until production of the 2nd prints.
7. — The connection points within one strip are especially selected and marked
on the diapositives for triangulation. For this purpose a recently designed marking
instrument of the ZEISS-AEROTOPOGRAPH Comp. is used. If certain connection
points are not suitable for the adjacent strips, special points will be selected there.
Thus it may happen that besides the control points more than 6 connection points
have to be measured. The triangulation is executed with the Stereoplanigraph. The
35
