and the application of photogrammetry to astro- 
geodetic measurements. He also formulated the 
basic laws of error propagation in long strip 
triangulations. He was probably the first person 
to use vector terminology in  photogrammetry 
literature (Finsterwalder 1899, 1932). 
Eduard Dolezal (1862-1955) of Vienna, Austria 
provided great international driving spirit as he 
became the founding President of the International 
  
Society for Photogrammetry in 1909. He also 
created the International Archives of 
photogrammetry. 
6.2.2 Pre World War II Base Developments 
Although organized civil aviation in the early 
1900s and the dirigible airships (like Zeppelins 
and Parsivals) and balloons opened up new 
explorations, there was a serious setback by the 
outbreak of World War I in 1914. However, the 
period between the two World Wars and extended 
through WW II (1918 to 1945) witnessed tremendous 
developments in establishing sound mathematical 
bases and computational tools to provide the 
necessary foundation for analytical photogrammetry. 
During this period developments in analytical 
photogrammetry were rather infrequent and mainly 
limited to countries and individual organizations 
with certain international interlocking 
involvements and implications. The following would 
give the highlights of basic developments during 
this period. One would notice some developmental 
efforts started during this period extended into 
the postwar years, as well as certain disappointing 
events to slow down possible progress. 
Reinhard Hugershoff (1882-1941), a professor at the 
Technical University of Dresden, Germany introduced 
in 1921 the Autocartograph, the first universal 
photogrammetric plotter and later at the Second ISP 
Congress in 1926, the Aerokartograph, a lighter 
instrument of the universal type which 
incorporated capabilities of control extension and 
phototriangulation. Here is an interesting story, 
which the author learned from Prof. Schermerhorn 
during his stay at ITC, The Netherlands, indicating 
one of many undesirable hurdles in the progress of 
analytical procedures. in 1920 the Dutch 
government contracted the German Luftbild GmbH 
(supported by Zeiss) for mapping several islands 
and a stretch of the Netherlands coast line. 
Hugershoff applied the pyramid method by 
using oblique photographs (Hugershoff 1919) and 
Luftbild applied a method developed by Fischer 
(1921). The ground control being inadequate, both 
the results were very unsatisfactory giving scale 
errors of up to 10 per cent and azimuth errors up 
to / degrees. These obviously created furor in 
Europe against any further practical application of 
analytical triangulation in mapping for almost 
twenty years. 
Otto von Gruber (1884-1942), a professor and 
scientific collaborator of Carl Pulfrich became 
famous for his landmark publication "Single and 
Double Point Resection in Space" (1924). His 
lectures in the Vacation Courses on Photogrammetry 
at Jena, first published in 1930 (with English 
reprints published in 1942) provided pioneering 
theoretical concepts (von Gruber 1942) on 
differential formulas of  projective relations 
between planes. It was von Gruber who observed in 
strip triangulation the influence of errors in ¢ on 
scale and on height. Based on experiments at his 
initiative, two important facts were emphasized, 
312 
viz., the usefulness of auxiliary data and 
instruments in order to avoid propagation of sys- 
tematic errors in strip  triangulation and the 
practical advantage of using wide-angle cameras. 
Heinrich Wild (1877-1951) presented in 1926 at the 
  
Second International Congress at Berlin his 
modified plotter prototype known as Police 
Autograph. Subsequently he founded a factory 
in Switzerland (Wild Heerbrugg Ltd.) where 
hundreds of well-known and widely used opto- 
mechanical autographs, comparators and (now) 
analytical plotters have been developed and 
manufactured. 
The Kern Co. (now in the Leica group) of Aarau, 
Switzerland joined the photogrammetric industry in 
1930 and continued its contribution up to this 
date. Umberto Nistri (1895-1962) of Rome, Italy and 
Ermeneguildo Santoni (1896-1970) of Florence, Italy 
also contributed essentially in designing and 
manufacturing instruments of various kinds as also 
in developing numerous corresponding mathematical 
concepts. Nistri patented in 1919 a method of 
spatial aerotriangulation. This method, however, 
was practically applied for the first time to the 
use of the Multiplex equipment around 1932-33. 
Georges Poivilliers (1892-1967) of France, Edgar H. 
Thompson (1910-1976) of the UK are credited with 
numerous analytical contributions and with 
designing instruments and  stereo-comparators. 
Thompson's finest contributions were in analytical 
(matrix algebra) developments, réseaux techniques 
and aerotriangulation by the method of 
independent models. Thompson edited the British 
journal "The Photogrammetric Record" for 14 years. 
Martin Hotine (1898-1968) of the UK War Office, 
although primarily a geodesist, published two 
landmark articles on photogrammetry concepts, 
"Stereoscopic Examination of Air Photographs" 
(1927) and "Calibration of Surveying Cameras" 
(1929). 
Willem Schermerhorn (1894-1977) of The 
Netherlands who became a professor at Delft in 
1926, began systematic tests of aerotriangulation 
in 1932 and applied these ideas to uncharted lands 
in the East Indies. In close cooperation with Otto 
von Gruber he contributed much to the understanding 
of error sources and error propagations in 
phototriangulation. He was also the initiator of 
the ISP journal "Photogrammetria". A post World 
War II Prime Minister of The Netherlands, he was 
also the founder (in 1950) of the International 
Training Center (ITC) for Aerial Survey at Delft 
(now located at Enschede; Schermerhorn 1964). 
His life was dedicated to the promotion of 
photogrammetry. 
V.P. Nenonen and Y. Vaisálà of Finland developed in 
1936 a method of aerotriangulation aided by horizon 
photographic records and statoscope readings. This 
initiated the concept of using auxiliary data for 
phototriangulation. 
Bertil Hallert (1910-1971) a professor of the 
Swedish Royal Technical Institute at Stockholm 
contributed much in developing numerical relative 
orientation procedures and establishing the 
concepts of calibration, and standards for testing 
cameras, comparators and stereoinstruments. The 
term "standard error of unit weight" was first used 
by him. 
Starting in the early 1930s through the 1950s, some 
theoretical and conceptual analytical developments 
were made at the Federal Institute of Technology, 
Zurich by Professor Max Zeller and his associates,