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Normal-angle photography of 1:5 000 scale is used as a basis for the 1:1 250 mapping. 1:4 
magnification from air photo to map requires secondary enlargement on an external tracing table. 
Roughly 3 x enlargement from air photo to map is the target for compilation of the 1:10 000 scale 
map. The basic material here is wide-angle and super-wide-angle photography at 1:25 000 scale. 
The internal tracing table is used for plotting. 
3. - Digitization - The Planicart and Planitop are also suitable for digital plotting, provided that 
encoders and an Ecomat-11 recording unit with suitable output equipment ara available. The Pla- 
nicart is presently in use at several organizations for production work (e.g. Hans Luftbild of . 
Munster /Germany). 
The Dutch Rijkswaterstaat of Delft has tested the Planitop for digital work and obtained very 
good results. Very large scales (1:2 000) and incremental recording were used. The linear enco- 
ders allow free-handed guiding between the points. The internal tracing table has proved to be 
very useful for check plotting. 
Other instruments for map revision 
  
  
1.- Double Projector - Like the Planicart and the Planitop, the Double Projector is a rigorous- 
solution instrument, that is, the image coordinates are converted to ground coordinates without 
any approximation. Projection is by the optical anaglyph method. The floating mark is guided 
either freehandedly or with the aid of handwheels. 
The Double Projector also has an internal tracing table into which the two air photos are pro- 
jected through a red and a green filter. The principle of map revision has here been realized in 
a particularly clear manner. The up-to-date stereo model is practically in direct contact with 
the map to be revised. 
2. - Orthophoto equipment (Ortho-3 and GZ-1) 
a) Ortho-3-Projector. A third projector can be connected to the Double Projector which allows 
orthophotos to be projected by white light. Operation is by the on-line principle. In other words, 
the vertical information obtained during scanning of the model in the Double Projector is used for 
Simultaneous production of an orthophoto. 
b) GZ-1 Orthoprojector. The Orthoprojector can be controlled by a Planimat either directly 
in the on-line mode or indirectly in the off-line mode using a storage unit and a scanning unit. Of 
particular importance for map revision is the off-line mode. This allows profiles stored on plates 
to be re-used for projection of a new orthophoto even many years after the original photoflight. 
This offers considerably advantages regardless of whether the orthophoto is directly used as a 
new map or whether the information required for revising a line map is taken from an orthophoto. 
  
  
Bibliography 
[L] R. Schwebel : An Equipment Concept for Plotting Photogrammetric Models. - Paper presented 
at 5 th Conference of South African Surveyors (Consas 1974) in Salisbury, spring of 1974. 
Abstract 
Of the photogrammetric equipment system offered by Carl Zeiss of Oberkochen, above all the Planicart and the 
Planitop are suitable for map revision and is economical very favourable in practice. Certain features such as a rigo- 
rous solution, the wide focal-length and plotting ranges and the internal tracing table are of particular importance in this 
context. The instruments have found a large number of practical uses. The applications mentioned here are intended only 
as examples. They do not make any claim to completeness. 
DISCUSSION 
Mr. HUNT - What are the enlargements used in your system ? 
H. SCHNEIDER - The enlargement between the model and the map is 4 x,and the enlargement between the photograph and 
the map is about 6 x. 
C. VIGNERON - Le SG1, enregistreur de profils, peut-il être connecté aux Planicart et Planitop ? 
H. SCHNEIDER - Non, seulement au Planimat.