Overview - 3D Postproduction: Stereoscopic Workflows and Techniques - page 28

Other issues can be more subtle. For example, in a beam-splitter rig, one
camera receives light transmitted through a half-silvered mirror. The
other camera sees light rel ected from the same half-silvered mirror. As
you would expect, L and R each has its own distinct color and density
characteristics since the light travels through different image paths on the
way to the imager.
One show may have the resources to address all 3D issues while another
show may have resources to resolve only a few of the worst ones. This topic
will help you identify and prioritize issues (and resolve them if you choose
to) for your specii c 3D show given the resources available to you.
The situation can become challenging if you have multiple issues in a single shot.
For example, a single shot may contain focus mismatch, vertical misalignment,
zoom mismatch, color mismatch, keystoning, and edge violations. It can be
difi cult to identify much less resolve issues in the correct order.
To make things even more challenging, correcting a 3D issue can introduce
new issues. Sometimes what we believe is causing an error is actually not
causing the error. For example, what looks like a vertical misalignment
between L and R, could actually be a rotational mismatch or a warp in
the mirror of a beam-splitter rig. If you misdiagnose the problem you risk
spending resources on issues that do not need resolution. In some cases, it
matters in which sequence we resolve issues.
For example, in our above example, let's say we had both a rotational issue
and a warped mirror issue. In what order should these issues be resolved?
Hard to say without knowing more detail about the show or the expertise
of the team doing the correction. In some cases, the only way to know if
something can be i xed is to try to i x it. If that does not work, try something
else. There may be technical or expertise reasons to i x one issue but not
another. So not only do you need to evaluate and prioritize issues in the
overall show, you also need to prioritize them within each shot, scene and
sequence. If you cannot correct the issue using the resources available then
you may need to select another take, recreate (re-shoot) the shot, omit it, or
turn to visual effects for 2D-to-3D conversion.
1.10 Workl ows Dei ned
As makers of 2D imagery know, each show is different because each show
has unique creative objective and resources. The same is true for 3D.