a given time and the other one refers to the
object shape and position in a given period.
Under the first aspect we can give as
an example the problem of determining the
shape of waves at the stern of a moving
boat, in constant regime and in suitable set-
tled meteorological conditions.
In this case the determination of wave
shape at a moment is sufficient as the wave
behaviour is kept during the whole period
when the conditions of regime, movement and
meteorological are constant.
The difficulty from photogrammetric
point of view consists only of synchronizing
the photographic process at two cameras.
Under the second aspect we can give as
an example the problem of determining the
behaviour of a convoy of barges tugged or
pushed during the whole period designed for
measurements, as these being accurately
known we get the apeed, number and way in
which the barges are grouped and coupled in
order to meet the navigation safety condi-
tions.
By neglecting some of the above-men-
tioned parameters, ships could be damaged
or wrecked.
The whole process of ship going
a non-pe.iodical aspect, both in the
of a successful passing and a failed
The variants for optimizing the
meters are studied on models, simulating
the transport on models at a reduced scale.
From photogrammetric point of view,
has
case
para-
the space-time determination has some dif-
ficulties both as concerns its tackling and
as concerns the equipment, if the non-peri-
odical process takes place in a shorter pe-
riod of time.
In this case, it is necessary to de-
termine the shape and position of the ob-
ject at short periods of time and this can
exceed the possibility of handling the pho-
togrammetric equipment.
In the photogrammetric laboratory of
our Design Institute for hoad, Water and Air
Transports there were made researches on mo-
dels and on true crafts and barge convoys
pushed or tugged on purpose of optimizing
the transports on the Danube - Black 3ea
Canal,
In order to determine the wave shape
passing.
58
and size there were made measurements on se-
veral models of pushers at a scale of 1/7 ha-
ving a constant speed of displacement both
in line and at curves with variable radii.
The drawing up was made at a scale of
1/50 having an equidistance of the contour
lines of 9.041 m ( Fig.l).
Another measurement was made on a model
of convoy of three barges st a scale of 1/5,
placed in an uncovered basin. The photos have
been taken for different displacement speeds
of the model.
The shape of the waves generated by the
convoy during its displacement and its posi-
tions are shown in the Fig.No.2.
The achievement of the above-mentioned
works and the conditions of a wider spread-
ing works which we were requested to carry
out have imposed the necessity of re-consi-
dering the synchronization conditions and a
better acquaintance with the operating pa-
rameters of the photogrammetric cameras,
used in the space - time photogrammetric
photographing.
The more necessary was to study these
parameters as, in the case of the very short
exposure times, nothing could guarantee a
priori that the two individual cameras works
identically because both of them show the
same working data.
On the contrary, it may be expected
that each camera have its characteristics
which make them different during the work.
These characteristics are not essential
when cameras are used for a photogrammetric
flight where a strip of stereoscopic sten-
dard photograms is made.
In the case of a syachronous photogram-
metric photographing, when two individual
photogrammetric cameras are used, the lowest
differentiations may influence very much the
accuracy of the results.
It should mainly be known the precise
effective time when the diaphragm of each
camera is opened, having in view that both
cameras show the same exposure time.
In case that this effective time ( when
the diaphragm was opened ) is different for
each camera and because we generally cannot
use the releasing mechanism, it should be pro-
vided an optimizing operation consisting of
an intended non-synchronization of cameras,
