The 3D coordinate system

Figure 2 shows the 3D coordinate system described above.

The blue axis is the axis that would be sticking out from the front of the man's eyeball.

(You can see that blue axis protruding slightly from the medium blue panel in Figure 1.)

The red axis is the axis that would be sticking out of the man's eyeball toward his right.

(A small portion of that red axis protrudes from the dark panel in Figure 1.)

The green axis is the axis that is sticking directly up from the man's eyeball.

(That green axis protrudes slightly from the top panel of the cube in Figure 1.)