In the spirit of the first see-through head-mounted display developed by
Ivan Sutherland, we and other researchers use the term "augmented reality"
to refer to enrichment of the real world
with a complementary virtual world. The augmented
reality systems we are developing employ a see-through head-worn display
that overlays graphics and sound on a person's
naturally occurring sight and hearing. By tracking users and objects in
space, these systems provide users with visual
information that is tied to the physical environment. Unlike most virtual
realities, whose virtual worlds replace the real world,
augmented reality systems enhance the real world by superposing
information onto it. The spatial tracking capabilities of our
augmented reality systems distinguish them from the heads-up displays
featured in some wearable computer systems.