Group discussion and collaboration would be enhanced by 3-D displays that produce imagery appearing to hover above, say, a tabletop. Visible 360° around the device, the imagery would occupy the volume straddling the flat surface of the table – appearing just slightly above, and quite a bit beneath.
From StarWarsWikia.org (Ep. IV)
At Actuality, we jokingly called these contraptions “Deathstar Displays,” after the Star Wars movies depicting hologram-ish imagery of the Deathstar for battle planning. More seriously, I dubbed them Theta Parallax Only (TPO) displays, as opposed to horizontal parallax only (HPO) displays, because the perspective changes as your angle (theta) to some vertical reference plane changes.
(New to 3-D? Mike Halle’s “Autostereoscopic Displays and Computer Graphics” wonderfully explains the physical limitations of where the imagery can appear to be before incurring window violations.)
Who’s working on this stuff?
An early patent from Actuality
Well, yours truly and my former co-worker Ollie Cossairt invented a few schemes in which a high-frame-rate image source directs imagery to an optical element, spinning like a turntable, that redirects the frames in an angular sweep around the audience. The optical element could take various forms: an off-axis lens, a diffuser-louver “sandwich,” etc.
G. E. Favalora and O. S. Cossairt, “Theta-parallax-only (TPO) displays,” US Pat 7,364,300 (Provisional: Jan. 12, 2004), (Filing: Jan. 12, 2005), (Issue: Apr 29, 2008). [Google Patents]
One of the cross-sections shown in the patent is:
A number of researchers have been building TPO displays, primarily (to my knowledge) in Asia.
Takaki Lab (Tokyo Univ. of Agriculture and Technology)
The Takaki Lab has a heritage of producing many interesting 3-D displays. Recently, they demonstrated a multi-projector system that illuminates a rotating surface. I am having a little trouble determining when their research began. But a recent paper is:
Shigeki Uchida and Yasuhiro Takaki, “360-degree three-dimensional table-screen display using small array of high-speed projectors,” in Stereoscopic Displays and Applications XXIII, edited by Andrew J. Woods, Nicolas S. Holliman, Gregg E. Favalora, Proceedings of SPIE-IS&T Electronic Imaging, SPIE Vol. 8288, 82880D (2012); http://dx.doi.org/10.1117/12.909603
Regrettably I cannot find videos or images of their work on their fascinating Takaki Laboratory web page.
By the way, I recommend Dr. Takaki’s excellent presentation, “Next-generation and ultimate 3D display” (IMID 2010) [pdf].
HolyMine “Holo Table”
I don’t remember how I stumbled across this company:
NICT – Conical diffuser: “fVisiOn”
Here is a different approach, using a conical diffuser. This is Shunsuke Yoshida of NICT’s Universal Media Research Center. Here is a link to the English page, which links to a more frequently updated Japanese page.
The project page has a list of related publications toward the end.
Microsoft Research Cambridge – Vermeer
The Vermeer system is a bit different; it incorporates re-imaging optics, and can also behave in an interesting dual mode of image-capture:
Zhejiang University (China)
Several people at Zhejiang Univ. are pursuing 360-degree displays, including Xu Liu and Zheng Zhenrong.
Xinxing Xia, Caijie Yan, Zhenrong Zheng, Haifeng Li, and Xu Liu, “48.3: A Novel Touchable Floating Color Omnidirectional-view Three-dimensional Display,” SID Symposium Digest of Technical Papers, 42(1) 699-701 (June 2011). http://dx.doi.org/10.1889/1.3621420
They have also built systems with “optics above the table,” i.e. similar in spirit to those from Actuality or USC:
Xinxing Xia, Zhenrong Zheng, Xu Liu, Haifeng Li, and Caijie Yan, “Omnidirectional-view three-dimensional display system based on cylindrical selective-diffusing screen,” Appl. Opt. 49, 4915-4920 (2010). http://mypage.zju.edu.cn/0099150/592595.html