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