1se 
“ca 
in 
rly 
tro 
Ing 
vey 
eo- 
ute 
ing 
atts 
er, 
K 4 
ith 
ich 
1to- 
"he 
lec- 
the 
Roelofs Wild radial triangulator. Furthermore, their coordinate recorder EK 2, belonging 
to the Wild Autograph A 7 was replaced by the new EK 3. 
According to the principles explained in National Report of 1956 the experience gained 
with each of these new instruments was made available to the factories without publication. 
The Ministry of Transport and Waterstaat obtained the patent on the design of a plotting 
instrument developed by one of its photogrammetrists H. J. Meier. : The: 1.T.C. and 
F. Goudswaard obtained the patent on the design of a plotting instrument as invented by 
this staff member. This patent was sold to the Wild Company. 
The small mechanical device, also developed by Goudswaard, designed for the computa- 
tion of corrections to the elements of a relative orientation according to the formulas for 
the numerical relative orientation in flat terrain is at present produced in the workshop 
of the I. T.C. and is available for its students and their services. 
Regarding the theory of orientation A. J. v. d. Weele developed a general approach to 
this problem from which by application of the same principle, all methods for flat and 
mountainous terrain, published so far, can be derived. This treatment of the subject will 
be used in volume I of the I.T.C. Textbook of Photogrammetry dealing with fundamentals 
of photogrammetry, which will be published by the end of 1960. 
Special attention was paid to the approximate plotting instruments (so called 3rd order 
plotters). F. Goudswaard of the I. T.C. proposed to the Zeiss factory a device for use of 
transparent photographs in the stereotope. H. C. Zorn made comparative studies on the 
various types of instruments, including the Russian Topographic Stereometer of Dro- 
byshew. Some of the results will be presented in an invited paper for Commission II. 
With the increasing use of camera orientation equipment such as horizon camera, solar 
periscope etc. it is very likely, that these approximate instruments can be simplified in 
future since it will then be possible to use instead of contact prints, rectified photographs 
obtained from a rectifier in the scale 1 : 1 on which the known values of y and o can be 
imposed. The I.T.C. is at present working on the design of such a rectifier. 
TABLE 6 in cHAPTER IV will show how and for which purpose the various plotting 
instruments (in the Netherlands) are being used. 
CHAPTER III. AERIAL TRIANGULATION 
II. 1. New developments 
The problem of the determination of control points is still the most important one in 
photogrammetry. Although not much progress could be mentioned in 1956, compared 
with the pre-war methods, it is a pleasure to state that the situation in 1960 is entirely 
different and that we can mention a few important developments which took place in the 
various Delft Photogrammetric Institutes. Before starting with the description of the prac- 
tical work carried out by K.L.M. Aerocarto and the Survey Department of the Ministry 
of Transport and Waterstaat we consider it desirable to make some remarks about the 
general trend, visible in the Delft efforts. 
The background of my remark in the 1956 report that there was not much news, not 
already known before World War II, was mainly due to the results of strip triangulations. 
In 1956 we had available a number of different solutions for a correct or a good approxima- 
tion of the least squares adjustment of a strip. It was evident, however, that the application 
of this theory to actual strip triangulations could not give any better results than such 
usual interpolation methods as that of Zarzycki. This opinion was based on the experience 
9