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AERIAL TRIANGULATION WITH AUXILIARY DATA, BRANDENBERGER 89 
U.S.A.: Lt. Col. A. M. Ahmajan, Assistant Commanding Officer, Army Map Serv- 
ice, Corps of Engineers, U.S. Army, Washington, D.C. 
Dr. A. J. Brandenberger, Professor of Photogrammetry, Ohio State Uni- 
versity, Columbus, Ohio. 
J. M. Lawson, Acting Chief Topographic Engineer, Geological Survey, 
Washington, D.C. 
Lt. Col. G. G. Lorenz. Chief Map Compilation Branch, Engineer Research 
and Development Laboratories, U.S. Army, Fort Belvoir, Virginia. 
K. T. Sime, Chief Photogrammetry Division, Aeronautical Chart and 
Information Center, U.S. Air Force, St. Louis, Missouri. 
G. C. Tewinkel, Chief Photogrammetric Research, Coast and Geodetic 
Survey, Washington, D.C. 
Introduction. 
In this section some general considerations are given to the subject of strip trian- 
gulation performed in first order stereo plotting instruments. Vertical photography is 
assumed. 
Strip triangulation is usually carried out by using the aeropolygon method or by ap- 
plying strip triangulation procedures which make use of auxiliary data. 
In the first method is used the elements of exterior orientation for the individual 
photographs of a strip triangulation are obtained by the wellknown procedures of relative 
orientation, scale transfer and coordinate transfer. Such strip triangulations generally 
yield a higher interior accuracy than those which make use of auxiliary data. The dis- 
advantage of the aeropolygon method, however, is the occurance of much larger closure 
errors when compared with the strip triangulation procedures using auxiliary data. This 
is due to the fact that the errors in a strip triangulation performed by the aeropolygon 
method accumulate with a much higher degree than those of strip triangulations using 
auxiliary data. Such a rapid error accumulation has the disadvantage that already in 
relatively short strips the correlation between X- and Z-errors is significant. Consequently, 
the adjustment of the X- and Z-coordinates can no longer be done independently when 
long strip triangulations of say twenty models or more models have to be adjusted. This 
is especially true in case of mountainous areas. The fact that the correlation between 
X- and Z-errors cannot be neglected in strip triangulations of a certain length complicates 
the strip triangulation procedure and makes the aeropolygon method less efficient. This 
disadvantage does not normally exist in strip triangulations using auxiliary data. 
In the strip triangulation procedures which use auxiliary data certain elements of 
exterior orientation of the individual photographs are immediately recorded during the 
flight. Such additional information (auxiliary data) might be obtained in terms of alti- 
tude differences between adjacent air stations (aerolevelling) by using a statoscope or 
an airborne profile recorder. Independent information on lateral and longitudinal tilt 
(w and p) are obtained when horizon cameras or solar cameras are used such as the solar 
camera of Santoni. Infrared oblique photographs taken with an auxiliary camera might 
be used to yield independent recording of drift by and swing x. Such auxiliary data is 
generally used as independent information and is mainly applied to reduce the excessive 
error accumulation of the aeropolygon method to such an amount that the X-, Y-, and 
Z-adjustment of strips can be performed independently. 
It was also suggested that auxiliary data be used for the adjustment of strip trian- 
gulations performed by the aeropolygon method. However, very little is known about the 
success of such a proceeding. 
The accuracy of strip triangulation using auxiliary data is greatly dependent upon 
the accuracy of this additional information. It is desirable that such auxiliary data would 
have an accuracy at least as high as that obtained by the aeropolygon methods. With