up to 85 degrees, and focal lengths of from 25 to more than 900 millimeters can be accommodated. A 
ground-distance display is provided. 
17. Gebry, J. 
Hungary 
RADIAL ALLOTTED ORTHOPHOTOSCOP 
The process and instrument, recited hereafter is the author’s invention. The orthophoto map making 
preparation can be carried on with any of the instruments for stereo-plotting. 
After relative and absolute orientation on the selected aerial photographs for orthophotographic reproduction 
purposes, a plumb point centered spiral is placed having a constant ‘d’ value whorl expansion. The spiral 
drawing is called the basic spiral. It can be examined together with the aerial photograph through the optical 
viewer of the device and by the use of a measuring mark. The preparations are as follows: The measuring mark 
is directed from the centre along the spiral line in a way that, during his movement in the stereoscopic spatial 
model, the measuring mark should remain continuously on the terrain's surface. In the meantime, the 
coordinatograph, connected to the stereo-plotting instrument, draws or scratches in a coating in accordance 
with the selected scale, the corresponding curve of the basic spiral placed on the aerial photograph. 
The total spiral curve is established after the analysis of the two models. 
The total spiral curve is no longer a regular spiral at all, it is distorted insomuch as the reciprocal value of the 
height differences and the perspective deformation. 
The curve is called the leading spiral. The leading of the measuring mark along the spiral line can be executed 
mechanically as well. If we had marked the leading spiral on the terrain before taking photos, then this curve 
would be presented on the photograph as a regular basic spiral. 
The three principal parts of this device of orthophotomap preparation are the three disks turning with the same 
angular velocity: the negative disk, the control disk and the orthophotomap disk. The negative is located on 
the negative disk. The content of the master negative is scanned by a narrow radial slot, which has the same 
length as the radial distance of the succeeding spiral. The slotted disk displaces within one revolution, with the 
slots length in radial direction outwards. 
The leading spiral of the control disk determines the area of the master negative projected through the slot, 
and the distance between the two succeeding spirals determines the degree of magnification. 
The content of the master negative passing through the slot is projected on a light sensitive material, exactly 
on the determined part by the leading spiral. 
The angular distortion due to the tilt displacement is continuously corrected by the K correction device. The 
constant change of magnification of the projection is carried out by zoom optics or cathode ray tube image 
transmission. 
By the above described procedure, it is possible to realize, even in the case of considerable height differences, 
accurate orthophotomaps without connection faults. In this case there are no zones lacking in sharpness, lost 
areas of image content or double projection. 
18. Graham, L.C. 
United States 
AN IMPROVED ORTHOGRAPHIC RADAR RESTITUTOR 
This paper presents a concept for a radar restitutor which provides a number of advantages over previous 
instruments. Technological developments in two fields have made this possible. First, the development of 
coherent optical scanners makes possible scanning mechanisms of high speed, high accuracy, and high 
resolution along with scanning light beams containing sufficient energy to overcome the noise, speed, and 
bandwidth limitations of CRT scanners and recorders. Second, the development of digital integrated circuit 
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