As with the MarkI display,
one of the Mark II's principal advantages
is that no user-worn viewing aids (such as LCD shutter goggles or
polarized glasses) are required for image separation. The system's
optics deliver the stereo information to the viewers' eyes as they
move through the viewzone.
The system layout is shown
below. A video camera monitors several
viewers as they move within the viewzone. The video images are
used as input to head-tracking software, running on an SGI O2,
which computes the viewers' center-head positions and reports
them to the rendering and display software.
Upon receiving the center-head
positions, the rendering and display
software either correctly renders left- and right-eye views of a 3D
scene for a viewer, or selects the proper views from a pre-generated
The head-tracking software
also generates an image that acts as
a "polarizing mask" for display on the viewer-tracking LCD. The
"mask" image (shown below) simply divides the viewer-tracking LCD
into regions of crossed linear polarization; the locations of these
regions correspond to the location of the viewers' eyes in the viewzone.
Left-right view separation
is accomplished by combining the left-
right image pair into a single image by interleaving their pixel rows.
The output polarization on successive lines of the image LCD alternates,
aligning with one or the other polarized regions of the viewer-tracking
LCD. Thus, left- and right-eye images are polarized differently.
In effect, virtual viewer-tracking
polarized glasses are optically
projected onto the eyes of as many as three moving viewers,
who may observe from anywhere in the viewzone while the system
provides a correctly-rendered autostereoscopic view of a 3D scene.
This project is sponsored
by the Digital Life Consortium at the MIT
Media Laboratory, Honda R&D Co., and the Office of Naval Research