3D Workflow: Production with an Added Dimension

3D glasses

Three-dimensional video can make for an amazing, immersive viewing experience, whether at the theater, on TV, or on the Web. There are various viewing technologies available to watch video in 3D. Stereo Anaglyph is the most common for television and web-based videos, which pair with the traditional Red/Cyan glasses. As technology develops, this is changing with the introduction of 3D TV's and 3D computer monitors, which use electronic shutter glasses. Polarized lenses are used in theaters. They allow the viewer to see the stereo image in full color. But regardless of how the video is viewed, all 3D video is created the same way.

Fortunately, for experienced production teams, this is a fairly straight forward process.  But even for novices, if you understand a few simple concepts, you'll be publishing 3d content in no time. So before we get too technical, let's get some lingo sorted out:

  • Anaglyph Images are two offset images (often displayed in complementary colors) that create depth when they're displayed together and viewed through special glasses. This displacement of the images replicates the parallaxdifference (when an object is viewed through one eye, v. the other eye). When you view anaglyph images through a pair of those stylish glasses, your brain is tricked into perceiving the image as 3D.
  • Beam Splitte is exactly what it sounds like. The splitter lets us take in light from a single scene, and then sends half the light two one camera, and half the light to another (slightly offset) camera. This allows you to capture the two anaglyph images.
  • Convergence happens when your eyes move together to help you maintain clarity when you're viewing an object.
  • Polarized 3D Glasses create the illusion of three-dimensional images by restricting the light that reaches each eye, an example of stereoscopywhich exploits the polarizationof light.
  • Shutter Glasses create the same are illusion of 3D space ad polarized glasses, but they do so by rapidly alternating which eye receives an image via alternate-frame sequencing. The shutter is created by a liquid crystal layer in the lens that gets dark when voltage is applied.

To create a 3D effect, we must use two cameras, the lenses spaced about the same distance apart as the human eyes. Since most production cameras are too large to be spaced this close to one another, a beam splitter is used to split the light off to the cameras. Each camera can have an adjustable overlap as a result, thus controlling the parallax. The further apart the cameras are offset, the greater the parallax and the more depth will be produced..

If the cameras are narrowly spaced, there is less depth overall, but this allows your subject to be closer to the lens. Likewise, when filming something farther away, increasing the spacing between cameras increases the depth effect. Note that it's important that your two cameras are synchronized, that will be important when you want to edit your video.

Thankfully, editing is fairly straight forward as well. We recommend that you bring the videos from both cameras into the same timeline, and make sure they are synchronized. We then hide the "right" camera and edit both tracks, using the "left" track as the reference. (This will be much easier on your computer's processor).  Once the initial edit is complete, we need to set the convergence point for each shot to determine what jumps out of the screen, what is flush with the screen, and what is behind the screen. We'll cover that in our next issue...