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The looking Glass display is horizontal parallax only (HPO). HPO is a common information reduction method in the 3D display world. Most holographic stereograms,

by mhalle 7y ago

The looking Glass display is horizontal parallax only (HPO). HPO is a common information reduction method in the 3D display world. Most holographic stereograms, all rainbow holograms, and all 3D lenticulars are HPO. Occlusion, horizontal motion parallax and stereoscopic cues are preserved, which are our primary 3D cues. The loss of vertical parallax changes computation from an N squared to N problem. An interactive display like the looking glass provides vertical parallax cues as a result of user interaction (rotating the object vertically with user interaction). This class of display also does not have accommodation cues, but in the range of 3d cues accommodation is the weakest. Looking Glass displays are great! Shawn and the team has done careful, practical engineering work to get these displays out there. Ref: I have a PhD in 3D display technology and worked with holography pioneer Steve Benton and his group at MIT to develop the most advanced holographic stereograms at the time. I own a Looking Glass display.

chmike 7y ago
Are the Looking Glass display real holograms with light interference patterns ? Or are they emitting different pixels in different view angles ?
- mhalle 7y ago
  No, they are not true holograms in the interference pattern sense. I am not fond of the misappropriation of the word, but Looking Glass is hardly the first. I had hoped plenogram would catch on (to make the connection to the plenoptic function that describes the travel of light in a scene).
- supermatt 7y ago
  https://en.wikipedia.org/wiki/Lenticular_lens https://en.wikipedia.org/wiki/Lenticular_lens
- tgvaughan 7y ago
  Aren't those two things essentially identical, at least as far as the resulting wavefront goes?
  - sp332 7y ago
    The Looking Glass only has 45 discrete views projected across 50 degrees (25 degrees left and right of center). I have one of the smaller ones and it's a very nice effect, but it's not the same as a "real" hologram.
  - dTal 7y ago
    In a sense, if the resolution is high enough. One notable limitation of the angular-pixel approach is that the angular resolution of the pixel becomes diffraction-limited as the pixel size shrinks - the puts you between a rock and a hard place with the twin goals of "small enough pixels that you can't see them" and "enough viewing angles that you can't perceive the steps", even if you had a hypothetical umpteen-zillion gigapixel display. "True" holograms are coherent across their entire surface, so they don't have this limitation. This isn't even close, though. Horizontal parallax only and only a few dozen angles (over a wide FOV!) puts it more in the territory of lenticulars than true lightfield displays. To be fair that is enough to achieve a 'wow factor', and a true lightfield display is a Hard Problem (that Fovi3d are trying to solve, if you're interested in the state of the art).
arcticbull 7y ago
Am I correct in assuming this is a parallax-barrier display similar to that on the Nintendo 3DS but much larger and higher-resolution?
aidenn0 7y ago
From back when I researched it, accommodation mismatch is a huge problem for a small (but significant) proportion of the population in terms of nausea or headaches. It's less of a problem for movie-theaters because accomodation is at infinity for the screen itself, so as long as they don't have too much for too long that is much closer to the viewer than the screen, it doesn't cause any issues, but it seems like it would be a major issue for a screen designed to be viewed up close?
- ksaj 7y ago
  The 3D glasses problem doesn't really apply here. With 3D movie glasses, everything is blocked out except for the 3D images. Some people feel queezy when their proprioception and visual input don't match. It's a little like car sickness. With the screen, they do match, as only what's on the screen is 3D. In that sense, it is like looking at a box with something 3D in it, versus being submersed inside something 3D like with the glasses. tl;dr With the screen you can move your head around and the world moves with it, so there is no sensory mismatch. But turning your head when going into a 3D warp speed starscape with 3D glasses on might easily cause someone to ralph on the poor sole sitting in front of them.
  - aidenn0 7y ago
    The issue I'm thinking of was still an issue even with early HOP lenticular displays (IIRC philips had a 7-view one in the 90s), and I seem to recall reading research that specifically identified accommodation/parallax mismatch rather than anything else, which is why large viewing distances do not have this problem.

by mhalle 7y ago

chmike 7y ago

Are the Looking Glass display real holograms with light interference patterns ? Or are they emitting different pixels in different view angles ?

mhalle 7y ago
No, they are not true holograms in the interference pattern sense. I am not fond of the misappropriation of the word, but Looking Glass is hardly the first. I had hoped plenogram would catch on (to make the connection to the plenoptic function that describes the travel of light in a scene).
supermatt 7y ago
https://en.wikipedia.org/wiki/Lenticular_lens https://en.wikipedia.org/wiki/Lenticular_lens
tgvaughan 7y ago
Aren't those two things essentially identical, at least as far as the resulting wavefront goes?
- sp332 7y ago
  The Looking Glass only has 45 discrete views projected across 50 degrees (25 degrees left and right of center). I have one of the smaller ones and it's a very nice effect, but it's not the same as a "real" hologram.
- dTal 7y ago
  In a sense, if the resolution is high enough. One notable limitation of the angular-pixel approach is that the angular resolution of the pixel becomes diffraction-limited as the pixel size shrinks - the puts you between a rock and a hard place with the twin goals of "small enough pixels that you can't see them" and "enough viewing angles that you can't perceive the steps", even if you had a hypothetical umpteen-zillion gigapixel display. "True" holograms are coherent across their entire surface, so they don't have this limitation. This isn't even close, though. Horizontal parallax only and only a few dozen angles (over a wide FOV!) puts it more in the territory of lenticulars than true lightfield displays. To be fair that is enough to achieve a 'wow factor', and a true lightfield display is a Hard Problem (that Fovi3d are trying to solve, if you're interested in the state of the art).

arcticbull 7y ago

Am I correct in assuming this is a parallax-barrier display similar to that on the Nintendo 3DS but much larger and higher-resolution?

aidenn0 7y ago

From back when I researched it, accommodation mismatch is a huge problem for a small (but significant) proportion of the population in terms of nausea or headaches. It's less of a problem for movie-theaters because accomodation is at infinity for the screen itself, so as long as they don't have too much for too long that is much closer to the viewer than the screen, it doesn't cause any issues, but it seems like it would be a major issue for a screen designed to be viewed up close?

ksaj 7y ago
The 3D glasses problem doesn't really apply here. With 3D movie glasses, everything is blocked out except for the 3D images. Some people feel queezy when their proprioception and visual input don't match. It's a little like car sickness. With the screen, they do match, as only what's on the screen is 3D. In that sense, it is like looking at a box with something 3D in it, versus being submersed inside something 3D like with the glasses. tl;dr With the screen you can move your head around and the world moves with it, so there is no sensory mismatch. But turning your head when going into a 3D warp speed starscape with 3D glasses on might easily cause someone to ralph on the poor sole sitting in front of them.
- aidenn0 7y ago
  The issue I'm thinking of was still an issue even with early HOP lenticular displays (IIRC philips had a 7-view one in the 90s), and I seem to recall reading research that specifically identified accommodation/parallax mismatch rather than anything else, which is why large viewing distances do not have this problem.