Schubin: The Holy Grail of 3D Is Not Yet in Reach
At SVG’s 3D & Beyond Summit on May 25 at the CBS Broadcast Center in New York, SMPTE Fellow Mark Schubin offered his take on alternatives to the two-camera/lens rigs that are the current standard in 3D production. Although many alternatives exist in the marketplace, he explained, none of them reach his multifaceted 3D Holy Grail.
Schubin began his presentation by illuminating some of the current issues plaguing two-lens 3D, from requiring twice the equipment to processing and distribution challenges. He also explained some 3D viewer challenges, from limited 3DTV penetration to perceptual conflicts. The elusive Holy Grail, he explained, would be a low-cost 3D system with no glasses, no ghosting, no vergence-accommodation conflict, adult-child compatibility, 2D-viewer compatibility, no extra personnel, one lens and camera per position, one signal path, and full resolution for all TVs and transmission.
Outside of integral and holographic systems, which Schubin dismissed as not happening any time soon, there are, in fact, some systems that come close to reaching that Grail.
Chromostereopsis, in which the eye lines can focus only on one thing at a time, is one possibility. The real world often matches chromostereopsis, with blue sky in the background and people in the foreground.
“It’s not easy for sports,” Schubin cautioned, “where people in the foreground or background will be the same colors, but ChromaDepth glasses can enhance this effect.”
Another possibility is the Pulfrich Illusion, in which one eye is darkened, so that the dark eye sees what was, while the clear eye sees what is.
“This is not so good for live,” Schubin said. “Maybe for a race like swimming, where the foreground people are always moving in one direction. When it’s done well, like it was for the Rose Parade, it looks good. When it’s done poorly, as for the Super Bowl halftime show, it looks bad.”
View-shifting, which he also referred to as wiggle-vision or forced-motion parallax, requires constant motion: “If it’s not subtle, it’s annoying, and if it’s subtle, it’s near invisible.”
The shifting-lens adaptor has been widely used, as has the Pulfrich Illusion and ChromaDepth glasses, but the greatest option for sports, Schubin suggested, is virtual-camera S3D, where a certain number of cameras around the stadium define the space that exists. Once that space is defined, he said, you can put a virtual camera anywhere, so it’s not difficult to put a second virtual camera 65 mm to the right.
“If you can do virtual cameras, you can do virtual 3D cameras,” he said. “It is successful, but it’s not necessarily commercial yet.”
The BBC, in fact, has been working on virtual-camera 3D at a pan-European lab in Belgium. So far, however, large-stadium sports are a problem.
Schubin also discussed the other stereo — stereophonic sound — to make a point that microstereopsis is a viable path to the 3D Holy Grail. He explained that, when it comes to cue significance, the top mechanism is occlusion, but the second-strongest is binocular disparity, or stereopsis. Even at a distance of miles, far outside where the strongest cue lies, people can still pick up some sensation of stereopsis, which the Sony Technology Development Group has achieved by using P1 cameras and an ordinary lens.
“They relay optics to split the image into the two cameras using some mirror systems,” Schubin said. “They showed the images at CES 2009, and a 2D viewer without glasses could watch that absolutely fine.”
A Dutch company, Digital Optical Technology Systems, developed a colored iris that can be put onto a camera to distinguish in-focus material from out-of-focus material, making microstereopsis nearly 100% compatible with 2D viewing.
Autostereoscopic 3D is another two-lens alternative, but Schubin said that technology is not quite ready, mostly because of the resolution quality obtained when dividing a 1920×1080 picture by 28 views, for example.
“It’s worse than the worst YouTube conversion you’ve ever seen,” Schubin said. “To call it NTSC quality is praising it. For the time being, we’re talking glasses.”
So where does that leave the industry on the issue of the Holy Grail?
- Low cost: Dealing with polarized glasses, we’ve come to that point.
- No glasses: None, no; inexpensive, yes.
- No ghosting: No. Ghosting is still a big problem.
- No vergence-accommodation conflict: No. That is still a big problem, especially for sports. “I don’t know how you shoot big sports and deal with vergence-accommodation conflict or miniaturization.”
- Adult-child compatibility: Not such a problem for sports, since 3-year-olds don’t want to watch the Super Bowl.
- 2D-viewer compatibility: Not unless we’re going to tackle microstereopsis.
- No extra personnel: We’re getting very close. Schubin was impressed with the automated software that 3ality Digital showcased at NAB; he noted that the company made a breakthrough with that software.
- One lens and camera: Not unless one of the above alternatives is deployed.
- One signal path: Yes, if you are willing to sacrifice resolution.
- For all TVs: Not yet.
To download the full presentation, visit www.SchubinCafe.com.