about geometric qualities of the photography were described (Bassus, 1900a). 
Height determination using two overlapping photographs was also reported. The 
time required for the determination of the X, Y and Z co-ordinates of one single 
point was 15 minutes, with a root mean square error of 1m (Finsterwalder, 1900). 
A few years later in an extremely stimulating paper, Finsterwalder, (1904) 
established basic photogrammetric ideas using the theory of projective geometry, 
least squares adjustment and co-ordinate transformation. He distinguished three 
S major steps in the whole procedure, which he called the fundamental photogrammetric 
operation. Firstly, the determination of the pivot points, as he named the traces 
of the base on the photographic planes of two, not necessarily vertical photographs 
of the same area, taken with a hand held camera from the basket of a balloon. This 
is equivalent to the interior orientation. The second step was the reconstruction 
WS of the object without determination of scale and exterior orientation, which clearly 
oS corresponds to the relative orientation. Finally, through appropriate choice of 
scale and careful determination of rotations, the model was compared to reality. 
| In the fascinating example that accompanied the paper, the various steps were 
explicitly presented and the final product of a 10 m contour drawing at 1:10000 
scale was illustrated. The claimed co-ordinate accuracy was t*1.1m. 
"S CTUM 
A comprehensive review of the various methods devised and employed in the 
extraction of metric information from balloon photography at that time was given 
by Dr.W.Kutta (Aachen) in Suering (1911). The chapter included elements of the 
determination of the principal distance and the principal point (camera calibration), 
it described methods for the computation of the camera station co-ordinates 
(resection) and gave hints on the transfer of points onto a map (paper strip 
method; restitution). 
ps 
At the same time, however, balloonists encountered numerous practical 
photographic problems, mainly due to the lack of suitable cameras. In the effort 
to enlarge the photographic field of view a number of "panoramic cameras” were 
constructed. The first apparatus of this kind is attributed to Woodbury in 1881 
(Gruber, 1932). This incorporated a revolving lens, through which several plates 
mounted on a prismatic drum were exposed. In succeeding years, numerous such 
panoramic apparatus were developed and patented, including Thiele's Panoramagraph 
which appeared in 1898 (Bassus, 1900a) and Scheimpflug's eight lens camera in 
x, 190h (Gruber, 1932; Thompson, 1966a). Their development, however, was not 
pursued, firstly, because of the development of new photogrammetric techniques 
and, secondly, because of the appearance of the aeroplane. Efforts to predetermine 
the tilts of the camera were also made. A fine example is the so called 
photogrammetric gun, which was designed by Professor S. Finsterwalder (Anon., 
1912; Bassus, 1900b; Georgopoulos, 1980). 
n Then came the aeroplane. It was only natural that balloons would lose in 
: importance as camera platforms. New techniques and better instrumentation were 
developed in the years that followed (Gruber, 1932). The merits of balloon 
a photography, however, were not completely forgotten and this technique was used, 
ams though rarely, for small projects and, primarily, for documentation purposes 
(Guy, 1932). It was only two decades ago that the interest in balloon photography 
was revived. Its economic value and its applicability in projects dealing with 
relatively small areas were recognised (Brains trust, 1960). Investigations of 
the capabilities of balloons were initiated (Brown and Newton, 1962; Ross, 1969) 
and certain applications were actually carried out. These included monitoring 
of hydrographic phenomena and marine observations (ASP, 1969; Newton, 196k), 
meteorological observations (Air Force Cambridge Research Laboratory (AFCRL), 
1961), study of the effects of nuclear and high explosive detonation in the 
atmosphere (AFCRL, 1967), agricultural and forestry applications (ASP, 1969; 
Private communication with J.R.Tallowin), testing of remote sensors (ASP, 1969; 
Reeves, 1975), monitoring water pollution (ASP, 1969), study of coastal dynamics 
(Sonu, 1969), X-ray polarimetry (AFCRL, 1970), radio altimetry and gamma ray 
astronomy (AFCRL, 1970) and, finally, remote sensing applications using multiband 
cameras (Reeves, 1975a and 1975b; Whittlesey, 1972 and 1975). The majority of 
these applications made use of large balloons capable of ascending to high 
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