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are thus possible. Likewise, in certain colored photos, containing an unusual 
amount of blue coloring in the comers, improvements can be made by the utiliza 
tion of certain yellow filters. 
(2) To supplement the basic capability of the GZI to produce ortho - 
photographs, steps were undertaken to provide it with terrain elevation plotting 
capabilities as well. A special dropped-line attachment (HS) was developed as 
were special techniques for its use. Basically, it operates as follows: 
(a) During the orthoprojection process an elevation spindle (Z) 
is rotated proportionally to relief variations. To it (Z) is connected a signal disk 
(T) by means of transmission gears (U) and operated by servos (D). The signal, 
represented by a specific circular slit in the disk, can be changed whenever a 
certain constant elevation is encountered. The slit is used to image the corres 
ponding signal or photographic media by means of an objective and mirror. 
(b) Through the judicious choice of number, size, and shape of 
slits on a given disk, and selection of appropriate transmission ratios, specific 
elevation intervals and scales of plots can be obtained. By arranging the dropped- 
line attachment parallel to the main slit diaphragm of the orthoprojector (at a 
distance of one photo size from the latter) both orthophoto and dropped-line 
portrayals may be obtained simultaneously. Utilizing graphical means, it is 
possible to obtain a contour plot subsequently from the dropped-line chart. 
b. The Hanimat was introduced in 1967 and it was designed on the mechani 
cal principle as a "second-order" stereoplotter for use as a precision coordinate 
measuring device and for use in the production of medium- and large-scale maps. 
Its main characteristics are: 
(1) Variable focal length and format capabilities. 
(2) Tracing table equipped with magnetic plotting surface. 
(3) Capability to set bx- and by- and bz- values in a wide range. 
Provision is thus made for the use of photos with high overlap ratios; for the use 
of terrestrial photography; and for simplified orientation. 
(4) May be connected to auxiliary equipment such as the printing head, 
printing counter, Ecomat, Profilometer, spotting projector, tilt computer, and 
the Orthoprojector. 
c. Another development of Carl Zeiss, Oberkochen, of a simpler version 
of equipment than the Planimat, is the Double Projector (DP-1). This is an econo 
mical second-order instrument well suited for plotting medium-scale maps as 
well as for map revision work; it is based upon the double projection system. 
The DP-1 differs from other double projection instruments in that it uses 
a pedal disk to achieve Z-motion during the vertical adjustment step involving the 
two projectors. This is especially useful in map revision work as it allows the 
comparison of elevation and planimetry to be made directly between the projected