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AER. TRIANG. WITH AUXILIARY DATA, AUTHOR’S PRESENTATION 101
ZUSAMMENFASSUNG.
Dieser Bericht gibt Aufschluss über Fortschritte, die auf dem Gebiete der Luft-
triangulation mit Hilfsdaten (Statoskop, etc.) seit dem VIII. Internationalen Kongress
für Photogrammetrie in Stockholm (1956) gemacht wurden. Um diesen Bericht möglichst
umfassend zu gestalten wurde ein Fragebogen an 21 photogrammetrische Organisationen
in verschiedenen Ländern verschickt. Von 14 Berichterstattern wurden Antworten er-
halten. Aus den einzelnen Landesberichten ergibt sich, dass die Lufttriangulation mit
Hilfsdaten seit 1956 wesentlich an Bedeutung gewonnen hat. Der Gebrauch von neu-
artigen Hilfsdaten wird zur Zeit studiert, wobei vorallem elektronische Messverfahren
in Betracht gezogen werden.
Author's Presentation of the Paper
Prof A. BRANDENBERGER: From the various
national reports, it follows that at present a
great variety of auxiliary data are used in carry-
ing out aerial triangulation. The variety is so
great that the following comprehensive summary
of the various systems or methods of producing
or using auxiliary data is given.
a. Aerial triangulation with statoscope and
altimeters. Statoscopes, radar profile recorders
and other meters yield air station altitudes or
air station altitude differences. If these data
are used in performing a strip triangulation
they can be converted into bz-values which
can be used as fixed bz-values in a first
order stereo plotting instrument — aero-levelling
method — or as additional information for
the adjustment of a strip triangulation per-
formed by the aeropolygon method. When sta-
toscope or altimeter data are used one has to
keep in mind that the accuracy of such infor-
mation depends on the inherent accuracy of the
instruments being used and the anomalies of the
isobaric surfaces. The instrumental accuracy of
statoscopes and altimeters can be determined by
appropriate tests, while the anomalies of the
isobaric surfaces and their influences upon air
station altitudes can be determined only from
additional meteorological information. If such
additional information is to be used, a sufficient-
ly dense network of meteorological stations must
be available. This requirement might be consid-
ered as an inconvenience since in many areas on
the earth there are no meteorological stations
available, or there is no possibility of obtaining
meteorological data to correct for anomalies of
the isobaric surfaces.
The anomalies of the isobaric surfaces depend
on the local atmospheric conditions which are
more or less different from country to country.
This means that in various areas or countries air
station altitudes determined from statoscopes
or altimeters are of different reliability. It has to
be pointed out, however, that under normal con-
ditions a remarkably high accuracy for the air
Archives 5
station altitudes can be obtained from statoscope
data. According to experiences in Finland and
Switzerland, the standard errors for statoscope
air station altitudes amount to one to two metres.
Altimeters normally yield a lower accuracy be-
cause most of these instruments are less sensitive
than statoscopes.
b. Another method is the bz = 0 method. Al-
though this method of strip triangulation does
not use auxiliary data in a strip sense, the proce-
dure is very similar to the strip triangulation pro-
cedure with statoscope data, that is the aerolevel-
ling procedure. For this reason, it is felt necessary
to include this method in this subject. When a
strip triangulation, according to the bz = 0 me-
thod in a first order stereo plotting instrument is
performed, it is assumed that all stations have the
same altitude, that is both bz in the instrument
are left on zero or are kept constant, and the
relative orientation is carried out by means of y
instead of bz. Since the above mentioned as-
sumption is not normally fulfilled considerable
lp of the “fixed” camera occur. The real air
station altitudes are then computed from these
Ag rotations in a similar way as the statoscope
errors are determined. With regard to the attain-
able accuracy for the air station altitudes deter-
mined in this way, the same considerations hold
as indicated for the statoscope method.
c. The third method we have to consider is
the radar profile method. Experience has shown
that by means of this method a high accuracy can
be obtained from relative heights from the air
stations to ground points on the profile path. This
accuracy seems to be higher than that which is
obtained for the relative heights from an aeropo-
lygon strip triangulation performed in a first
order stereo plotting instrument. There is no
doubt that sufficiently accurate distances from
air stations to profile points which are measured
by the radar profile recorder represent very
valuable auxiliary data which can greatly con-
tribute to stabilise strip triangulations and to
reduce the excessive error propagation of the