— 22 - 
INTRODUCTION 
In this section some general considerations are made on aerial triangulation with au - 
xiliary data. 
Such auxiliary data are airborne recorded data for various exterior orientation ele - 
ments of aerial photography used for aerial triangulation for which at present time nearly ex - 
clusively vertical photography is used. In aerial triangulation a distinction is made between the 
universal stereo aerial triangulation method and radial triangulation which method yields only 
horizontal positions of the points determined by this method. In both cases auxiliary data can 
and/or are used in perfoming such aerial triangulations. In the practive of aerial triangulation 
there are three main methods, namely aerial triangulation with single high-altitude photogra - 
phy (or models), strip triangulation, and block triangulation without or with principal strips (tie 
strips). These three main methods can be performed without or with auxiliary data. In the first 
case aeropolygon strip triangulation and block triangulation consisting of such strip triangula 
tions are well known methods, while in the second case aeroleveling strip triangulation and ae - 
roleveling block triangulation are common methods. 
At the present time aerial triangulation is mostly performed by first order stereoins - 
truments (Nistri Photo Sterograph Beta 2, Poivilliers Stereotopographe Type B, Santoni Ste - 
reocartograph Model IV, Thomson-Watts Plotter, Wild Autograph A7, Wild Autograph A9, 
Stereoplanigraph Zeiss C8) and to a lesser degree by second order stereoinstruments (Wild 
Stereoplotter A8 etc). In recent years more studies were made in the field of analytical aerial 
triangulation using various types of comparators (Cambridge comparators, Hilger and Watts 
Recording Stereocomparator, Mann Comparator, Nistri Stereocomparator Mod. TA3, SOM 
Stereocomparator, Wild STK-1 Stereocomparator, Zeiss-Jena Stereocomparator, Zeiss Aero- 
topograph PSK Stereocomparator) and a great variety of electronic high speed computers. Basi 
cally it can be stated that analytical aerial triangulation is still in a development stage and on - 
ly in a very few countries (e.g. Great Britain and France) this method is already put in prac - 
tical use. Quite recently a new approach for the performance of aerial triangulation is under 
consideration using analytical plotters. In all these various procedures of aerial triangulation 
using first or second order stereoinstruments, analytical methods or analytical plotters auxilia 
ry data are either used or there exists the possibility of using them. 
The basic idea of using auxiliary data in performing aerial triangulation is to deter - 
mine airborne orientation elements of the aerial photography with the purpose of reducing the 
amount of ground control to be determined to a minimum. The final goal of this endeavour is 
ultimately to determine practically all ground control for mapping purposes by airborne me - 
thods (using a maximum of auxiliary data) to eliminate nearly completely the tedious, time and 
cost consuming ground surveying in large areas of the world. This trend is clearly demonstra 
ted by the new approach of the U. S. Air Force to develop an integrated photogrammetric map 
ping system for world wide photo mapping missions which would greatly reduce ground surve - 
ying operations. If one considers the fact that an adequate density of available ground control 
for large and medium scale photogrammetric mapping exists only for about 1 percent of the 
continental area of the earth it is obvious that such efforts are of great merit. 
At the present time the following auxiliary data are used or can be used for the perfor 
mance of aerial triangulation : 
1. Electronically determined horizontal coordinates X and Y for the exposure stations of 
aerial photography used for aerial triangulation by using Shoran, Hiran or in the near fu 
ture Shiran distance measurement and trilatération techniques. 
2. Absolute or relative altitudes for the exposure stations O of aerial photography used for 
aerial triangulation, determined by statoscope, altimeter or APR. 
3 Recorded lateral and longitudinal tilts co and <P of aerial photography used for aerial tri 
angulation, by horizon cameras, gyro recording systems, etc.