Overview - 3D Postproduction: Stereoscopic Workflows and Techniques - page 26

discomfort nor excessive discontinuity for your audience. It provides a
foundation on which the creative work of the show can be built. Essentially,
good 3D is a collection of targets that take into account the severity and
frequency of issues (and combinations of issues) in relation to the resources
available to resolve the issues. Examples of targets include maximum
negative (near) parallax and maximum positive (parallax).
Who decides what constitutes good 3D? Good 3D is a collective understanding
by the team or specii ed by team leaders or other experts. In some cases,
person or persons in the stereography role provide opinions as to what is
(or will be) comfortable and continuous.
1.9 Issues
Issues are events in 3D frames that generate (or might potentially generate)
discomfort and/or discontinuity. You might have only one issue in a shot
or you may i nd multiple issues. Issues vary in terms of:
• severity
• duration
• frequency
• combination with other issues
An issue for one shot, scene or sequence may or may not be an issue
in another shot, scene or sequence. If there is one issue there is a strong
possibility that there are others. Issues can change in severity over time.
Some are intermittent or one-off, others are constant. Most 3D issues involve
mismatches between L and R.
Every natively shot show will have issues. The point is whether you need
to resolve these issues in order to deliver your dei nition of good 3D. You
also need to deal with day-to-day issues that you know from 2D post: barrel
distortion, shutter problems, focus problems, depth of i eld, exposure, lens
chromatic distortion, and compression artifacts, to name just a few. The issues
can be more challenging to resolve in 3D, especially when these errors occur
differently between L and R.
Some differences between L and R are perfectly normal and expected. One
common example is that L or R is l ipped (upside-down) compared to the
other. This is a natural consequence of imaging using mirrors, as in a beam-
splitter rig and must always be resolved prior to additional post work.