6 
Optical magnification 
6x, lOx (l4x variable to 
28x) 
Plotter scales 
0.5x to 30x at 25°/° 
increments between steps 
Maximum model to photo scale = 12.25°/° 
Plotter table dimensions = 1360 x 1060 mm 
Plotting coordinates = XY, XA, YZ, and X or Y 
There are other features of a more detailed nature but which are 
not important for the substance of this paper. 
4. Safety - Error Features of the AP-2 
The AP-2 is more fool proof in its mechanical operations than a 
contemporary type instrument. No combination of quantity values which 
result in a photo point going beyond the limits of machine motion are 
permitted while the comparator tables are connected to computer out 
puts. It is also impossible to enter data which will cause the 
comparator table run to exceed machine limits. If such data is entered 
from the console while outputs are connected to the comparator tables, 
correction is made until the machine reaches a limit switch after 
which it returns to its original state. If input is made through the 
hand wheels or foot disc, the comparator table is disconnected when 
mechanical limits are reached. If input is still continued, the 
computer will continue to accept data; but the relation between the 
computer and the comparator tables is destroyed. Before this 
situation occurs, however, a warning signal is given so that the 
operator can cease his motion. 
5• Operations Which Can be Performed on AP-2 
The AP-2 can perform any operation capable of being done on a 
conventional analog machine. It is easy to operate, so much so that 
after interior orientation and storage of constants into the computer, 
a fully trained analog operator finds little difficulty in applying 
the usual analog techniques of orientation and plotting used on 
conventional instruments. If he is an imaginative person, he will 
find this instrument makes it convenient for him to perform these 
functions more easily by allowing him to drive directly to selected 
positions to observe parallaxes and make other desired settings. In 
addition to the analog techniques, the machine allows the use of an 
automatic 6 point parallax least squares solution for relative 
orientation. This solution for whole frame photos converges quite 
rapidly to the point where an operator wishes to take over to make 
final adjustments to the model.