icht-topographischen 
n the instruction, 
ed, does not yet 
ecial photogram- 
mann, Zürich 1950. 
irich 1948. 
, Zürich 1946. 
'ountry in having 
otogrammetrie in 
ed on from your 
to make a trans- 
are able to read 
ear the question 
XX interest to the 
igton, D. C.) has 
book. They are 
(phy and plotting 
13 
Austria: 
No new photographic methods are developed, but experiments to develop 
special methods for plotting stereoscopic pictures from optical and electron 
microscopes have been planned or are being carried out. 
Belgium: 
For the deformation measurements mentioned under (1a) a special 
camera had to be built.: 
Focal length — 140 mm, principal distance — 196 mm, front distance — 490 mm, plate 
size = 13 X 18 cm. 
Summary of the work of M. G. Lemaire on the plotting of mollusc shells 
for biometric studies. 
In the biologic experiments (1b) the two main problems to solve were: 
(1) As the choice of objectives available was limited, a diagram was established for those 
photographing conditions, which allow a maximum of precision at the plotting. 
This diagram was made for a camera of the type that is used today, namely a solid 
camera with fixed principle distance. See the above mentioned publication by Mr 
Lemaire (1b). 
(2) The difficulties encountered concerning the distortion of the camera made it necessary 
to find an accurate method of measuring this distortion. This method is described in 
the publication mentioned. It is based on the altimetric deformations of the stereo- 
model of an object in the horizontal plane (a grid). It is evident that this model must 
be produced under well determined conditions. Maximal error in the plane of the 
photograph: 0,02 mm. Mean square error: about 6 4 
Geometric conditions: À solid camera, the focal plane frame of which is a circle, with 
a diameter of 125 mm and a fixed principal distance about 165 mm. Photographs were 
taken with vertical axis perpendicular to the horizontal plane of altimetrique reference. 
Adjustment and realizing of base is achieved by deplacing the object. 
Definition of the planimetric scale through control points, the distances of which are 
measured in a comparator. Definition of the height-scale through known height diffe- 
rences. 
The measurement of the distortion was made according to the method developed at 
»l'Institut Géographique Militaire». 
France: 
(a) The use of photogrammetry in criminalistics. 
Terrestrial photographs are always taken after important crimes and 
accidents. In exceptional cases these photographs are plotted in a precision 
instrument to obtain numerical information. 
(b) Forestry photogrammetry. (See special section). 
(c) Photogrammetry for hydrographic purposes. 
I. Aerial photographs are commonly used in hydrography when search- 
ing for very shallow shoals. For this purpose are used photographs taken 
at low tide or. when the tide is rising. In the first case the shoals are seen 
as small dark spots, in the second they are revealed by the whirl they cause. 
Their positions are decided after identification by graphical plotting, but 
their heights must always be directly surveyed. 
II. Aerial photographs are also used to decide the depth near the coast. 
For this purpose the photographs must be taken during a slight back wash 
so that the crests of the waves appear on the photograph without breaking.