Overview - 3D Postproduction: Stereoscopic Workflows and Techniques - page 6

2D-to-3D Conversion
2D-to-3D conversion is a distinct post specialty in itself and outside the scope
of this topic. The discussion of the relative benei ts and drawbacks of “ natively
shot ” (3D imagery acquired live) and “converted” 3D (3D imagery acquired by
deconstructing and rebuilding elements of 2D imagery) is ongoing. To a 3D post
team, there is no technical difference in handling image pairs generated by live
3D photography and imagery generated by conversion. Each method has its own
peculiarities and generates its own issues and error conditions. A decision to
go with a primarily natively shot workl ow as opposed to a primarily converted
workl ow for a show is an aesthetic and i nancial one. The line between the two
approaches—native vs. converted—has already begun to blur. These methods are
by no means mutually exclusive. Both can be and have been successfully used
in mainstream 3D productions.
In fact, most natively shot professional 3D shows use some kind of 2D-to-3D
conversion techniques and tools somewhere in the post process. For example,
most graphics (lower-thirds, bugs, credits, titles) in otherwise native 3D shows
are 2D-to-3D conversions. The graphics are created in 2D, and then recreated for
3D simply by moving the virtual camera, re-creating the other eye, and rendering
each eye, then compositing L and R into the live action. In the context of this
book (which primarily addresses natively-shot independent 3D shows) conversion
is considered a visual effect. Conversion is a potentially extremely useful technique
to visual storytellers, especially when it comes to salvaging shots that could not
otherwise be saved with depth or geometry tools.
1.1.2 Dei ning Our Terms
3D terms have different meanings to different people. Even the meaning of
critical terms (e.g., “convergence” and “parallax”—more on these two later)
is up for debate. The important thing is discovering what these terms mean
in the context of your show.
Creating an informal glossary is one of the most important things you can
do to give yourself and your show the best chance of success. In this spirit,
underlined and italicized words or phrases are also contained in the Glossary
in the Appendix. I encourage you to rei ne these dei nitions and create new
ones that make sense for your show. Part of what makes 3D exciting is that