Figure 3-9. Angular discernible difference.

TM 9-258

When a person looks at two objects and

in the angles of convergence to the two objects, one of

attempts to determine which is farther away, the lines of

the objects will appear more distant.

sight from both his eyes converge or come together to

h. The

difference

between

angles

form angles on both of these objects. The angles

convergence may be slight but the brain possesses the

formed by the converging lines of sight are the angles of

faculty of distinguishing between them. The ability to see

convergence (B, fig 3-8). If the angles of convergence to

stereoscopically is dependent upon the ability to discern

both objects appear to be identical, there is no

the difference between angles of convergence

impression of one being farther away than the other. If

there is a difference

Figure 3-9. Angular discernible difference.

3-13