Fundamentals of Wearable Computers and Augmented Reality, 2nd Edition

69Head-Mounted Display Technologies for Augmented Reality

for very high-resolution and wide FOV. The VRD assures focused images all the

time regardless of accommodation of the eye, in exchange for a small exit pupil.

Head-mounted projective displays (HMPD) present a stereo image onto the real

environment from a pair of miniature projectors (Fisher, 1996). A typical congura-

tion of HMPD is shown in Figure 4.6a. From the regions in the real environment that

are covered with retro-reective materials, the projected stereo image is bounced

back to the corresponding eyes separately. Without the need for eyepiece, this design

is less obtrusive, a