19 
e ). Plotting deviceo 
The drawing table (1155 x 865 mm) is attached at the right of the instrument. For plotting, 
a stable parallelogram pantograph is connected to the tracking unit. The transmission 
ratios are between 1:2. 5 and 2. 5:1. 
III. 6 Topocart of VEB Carl Zeiss Jena. 
a). General. 
After the development of the super wide angle multiplex some 12 years ago, the aim 
was to build a new topographic plotter. This was finished as a compact plotter with a 
mechanical projection system in 1966. The photographs are co-planar and connected 
to the plane analogue computers by mechanical links. 
Application. 
Inputs: 
9" x 9" photography and smaller; diapositives, negatives and paper prints; near vertical 
and terrestrial photography; normal-, wide- and super-wide angle photographs (c^ 
50 - 215 mm). 
Outputs: 
Topographic maps (planimetry and contours) in medium and small scales, cross 
sections for engineering applications, some non-topographic applications. 
range 
• I 
b). Projection system. 
The projection system consists of the following parts: 
1) . cross-slide systems (xy) for the photo-carriers, 
2) . setting and reading devices for orientation parameters (cp,u),x, c ,c ), 
x y 
3) . straight-edged rulers with rotation axes - representing the projecting rays, together 
with the perspective centres, projected on the XZ and YZ coordinate planes, 
4) . mechanical plane computers for the corrections for tilts 9 and 00 (linked with the 
straight edges under 3) and the setting devices for orientation, 
5) . mechanical links between the plane computers and the photo-carriages. 
The projection system is the realisation of geometric principles, devised by Manek, 
by means of straight edged rulers, rotatable about axes representing the perspective 
centres, and the attached plane mechanical computers. The computers consist of several 
interconnected rulers. They are to some extent similar to the "relais" of the French 
Poivilliers-Stereotopograph B. The tilts 9 and 00 and the principal distance c (resolved 
into c and c ) are introduced to the mechanical computers, the swings x to the photo- 
x y 
carriers, and the base components bx, by, and bz to the base assembly. 
During tracking, the motions of the tracking device are (twice reduced) transferred to 
the split mechanical model points. These cause rotations of the straight edged rulers 
which are connected with the computers for tilts. These computers control, by means 
of mechanical links, the displacements of the photographs with respect to the fixed 
observation system.