Panasonic AG-HMX100 Manual page 3

Convergence, Parallax, and Depth
When the parallax value of the pair of images of an object is negative, the left-eye image
of the object is seen on the screen at a position that lies to the right of its right-eye image.
When a viewer converges the image pair, the 3D object seems to be located in front of the
screen plane. When the parallax value of the image pair is positive, the left-eye image of
the object is seen on the screen at a position that lies to the left of its right-eye image.
When a viewer converges the image pair, the 3D object seems to be located behind the
screen plane. When the parallax value is zero, the two images of the object overlap at the
screen plane. In this circumstance the object seems to the viewer to be located on the
screen plane. When a viewer's eyes are focused on the screen and converged on an object
that appears to be in front of the screen (i.e. an object with negative parallax), the viewer's
left and right eyes cross. And when a viewer's eyes are focused on the plane of the screen
and converged on an object that appears to be on or beyond the screen (i.e. an object with
zero or positive parallax), the viewer's eyes remain uncrossed. Because crossing the eyes
can cause physical discomfort, filmmakers are often cautious about using excessive
negative parallax, choosing instead to limit the degree to which objects are allowed to
intrude into the viewer's space
1. eyes focused on screen, left image
to right of right image (negative
parallax). The object seems to be
located in the viewer's space
(in front of the screen), or in
negative z-space.
Fig.3 – Convergence, Parallax, and Depth
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1. This caveat applies in particular to smaller-screen venues. In giant screen venues such as
traditional IMAX theaters—with screens up to five times the size of those in digital cinemas—
negative parallax is considered to be easier to experience, affording viewers the sense that they
are not simply watching a film but that they are immersed in it. This immersive factor, which can be
attractive to Hollywood films, is an argument in favor of the development of digital projectors that
are capable of displaying bright images on giant screens.
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2. eyes focused on screen, left image
to left of right image (positive
parallax). The object seems to be
located in the screen space
(beyond the screen), or in
positive z-space.
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