- 6 - 
adjustment programme as such would not impose any special conditions or restrictions of its 
own. 
7) The theoretical accuracy of a procedure as depending on the theoretical approach ; existen 
ce and rate of convergence of iterative and relaxation procedures. 
Due to the amount of data to be handled and the intensity of processing especially in 
block-adjustment these considerations become more and more independently important, each 
with special requirements and inherent rules. At present the main concern is directed towards 
items 2) and 3), namely the direct computational problems. The theoretical approach-for which 
generally the method of least squares is accepted - is often made dependent on what seems di 
rectly feasible by certain computers. 
2. Strip-Adjustment 
2. 1 Although strip - adjustment is a very old topic and the traditional adjustment procedu 
res are widely applied in practice, this period has seen considerable development and realiza 
tion of some new procedures based on the use of medium class or even small digital electronic 
computers. 
The discussions about the theory of errors of strip-triangulation has continued along 
the well known lines and arose also in Russia where obviously the increased use of aerial tri 
angulation has revived the interest in this subject (see [2] - [10]). 
It seems that wherever digital electronic computers have been installed for photogram- 
metric use the well known correction formulae for strip-adjustment using polynomials of 2 nd 
and 3 rd degree have been programmed and are in use ([11] - [22]). Some authors have a strong 
preference for conformal polynomials. The arguments put forward in favour of them do not, ho 
wever, seem to be conclusive. From the point of view of accuracy obtainable it probably does 
not matter very much whether conformal or non conformal polynomials are applied. Theoreti 
cal or experimental comparisons are, however, not yet available. 
2. 2 Based on the use of even small electronic computers, extensions of the elementary poly 
nomial adjustment procedures have been developed and are applied in practice. The extensions 
basically follow two lines of completion : 
a) In [12], [23] - [25] procedures of strip-adjustment have been proposed, some of them being 
programmed and practically applied, which consider the interrelation between corrections in 
planimetry and heights. They are therefore also applicable for mountainous terrain. Although 
the formulae, the actual computing prescriptions, and the computer programmes are set up 
differently, these procedures are equivalent to the three-dimensional treatment of strips. The 
authors use as mathematical basis mainly the conventional polynomials of 2 nd and 3 rd degree, 
which marks the theoretical limitation of the approach. 
b) The well known limitation of polynomials is that they are not flexible enough to adapt them - 
selves sufficiently to all strip-deformations which are sometimes known with a sufficient num 
ber of control points. Then polynomials of low degree cannot respond to the full information 
available because of their limited number of degrees of freedom. Several authors have attemp 
ted to overcome this drawback by suggesting the use of polynomials of higher degree which can 
be applied easily with electronic computation ([11], [20], [24], [26]). In [27] it has beén shown, 
however, that there are serious objections agairfst these procedures from the point of view of 
theory of errors. By using polynomials of higher degree one has obviously yielded to the com 
puting facilities without considering the validity of the photogrammetric approach. 
2. 3 In view of the capabilities of electronic computation a more general theoretical approach 
to the problem of strip-adjustment has been pursued in [28]. It is the least squares approach 
based on the well known theory of the double summation of errors in the aeropolygon triangula 
tion. This approach had previously been worked out only for special control distributions but