However straight lines in the 3D virtual world
will still only be perceived as exactly straight when
viewed from the correct position. It should be noted that
this dependence on viewer position is true for all
immersive displays including stereoscopic displays. The
only solution is to employ head tracking so that the
content changes with viewer position, this by definition
means the environment only appears undistorted for a
single user.
For projection surfaces with corners it is much more
important to be located at the correct position otherwise,
for example, objects moving in a straight line that crosses
a discontinuity such as a corner will appear to bend for all
viewing positions except the one position the warping is
computed for. Similarly camera panning will result in
very obvious distortions at the corners. Fig. 8 is an
example of warping where the virtual environment is
projected onto three walls and ceiling in a rectangular
room, the game player position is arranged directly above
the mirror such that their peripheral vision is filled and
they don’t experience reflected light off the mirror.