Introduction
During the 1964 Lisbon Congress, K.G, L’6fstrom, one of the great pioneers
of the auxiliary instrument idea, stated that the current highly praised
methods of applying auxiliary data have been in existence for more than
30 years without having found their appropriate place in photogrammetrie
practice.
The author has the impression that the above statement is equally valid at
the present moment, since no significant changes have been observed either
in development of hardware and techniques or in the general attitude of the
potential users in the period since the Lisbon Congress.
This apparent reluctance to use auxiliary data in aerial triangulation
might he due to the necessary investment in equipment and the resulting
technical modifications to the survey aircraft; the lack of skilled
personnel and general know-how required for the operation of the equipment;
ignorance of the possible applications of auxiliary data, possibly combined
with a fear of complicated procedures in execution and adjustment and
finally a lack of knowledge of the obtainable results and the economic
consequences of the use of auxiliary data.
Under these circumstances and in order to stimulate the further development
of equipment and methods and to broaden the field of potential users, it
might be useful to attempt to give a complete analysis of the whole complex.
This will entail a survey of all available instruments for obtaining
auxiliary data, their known range of accuracy and their place in the
geometrical model of aerial triangulation 0
Furthermore, a discussion of possible methods of application and their
respective technical merits will be given, followed finally by an estimation
of the obtainable accuracy of results with different auxiliary data.
GENERAL REVIEW OF AVAILABLE AUXILIARY DATA.
The following table shows the main types of auxiliary instruments currently
available and the points of view from which these will be discussed.
CHARACTERISTICS OF AVAILABLE AUXILIARY DATA
STATOSCOPE (HYPSOMETER)
APR
LASER-APR
HORIZON-CAMERA
SOLAR PERISCOPE
GYROSCOPE
INERTIAL PLATFORM
HIRAN
SHIRAN
AERODIST
DOPPLER
TYPE OF INFORMATION
RANGE OF ACCURACY
GEOMETRICAL MEANING IN
PHOTOGRAMMETRIC SYSTEM
GENERAL REMARKS CONCERNING
STATE OF ART
RESTRICTIONS
FUTURE TRENDS
Table 1