at the same time it drops the pencil onto the pencilled 
manuscript, this giving a pencilled document in real 
space as to what is already recorded onto the magnetic 
tape. 
shows the pencil plot, To obtain the butt join between stereo 
models, a line is drawn (or photographically exposed) onto the 
dispositive from the top to the bottom through the principle point. 
The operator, when traversing through the model, stops his 
floating mark on the line and records the Y value for that point 
onto the pencilled manuscriptimmediately in front of him - then 
in the next model, the operator does the reverse operation by 
moving the hand wheels, he moves the floating mark up to that 
particular coordinate in the Y value and over onto the line seen in 
the stereo model, thus placing the floating mark on exactly the 
same spot to commence his contouring into the next model. 
shows plotting in progress 
shows an enlarged photograph placed onto the internal plotter of 
the Planimat, For our system we field-edit prior to compilation 
such that once the stereo operator has finished his recording of 
topographic detail from the stereomodel, he can position himself 
approximately with the enlarged photograph and, then by view of 
the stereomodel, position his floating mark precisely with the 
Stereoplotter, he keypunches the information onto the magnetic 
tape to be processed later and drawn by the ADM.