technical question regarding retro reflective screen Gain

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06-18-2019, 07:25
taxayy

technical question regarding retro reflective screen Gain

I was wondering how much Gain you would get if the video projection beam was coming out towards a retro reflective screen nearly exactly from your eye position.

In my own home theatre the projector is on a tripod rather than mounted on a wall and the screen is a 120'' retroreflective one. I've always noticed when I crouch to grab something from the floor (the beer), the image gets so bright when my eye is amost in the same angle of incidence as the projection lens that the light dazzles me.

But the question of just how much Gain you get at that angle come to my head when I saw this:

https://www.youtube.com/watch?v=XPOgLt_73cY

To summarize the video it's a head-worn, very compact dual projector which directs the projection beam with special optics (a reflective polarizer and QWP) to the screen and back to your eyes. So I'd guess you could expect very bright images even if the source LED wasn't very bright in this. Is 5.0 gain a reasonable estimate?
06-19-2019, 11:28
buffo

I hate that they use the term "gain" to describe how bright a screen is. They should be talking about reflectivity. Grrrr.

To further complicate things, the "gain" that most screen manufacturers quote is actually a comparison to a standard coating, like titanium dioxide, and not a measurement of the actual percentage of light that is reflected. (Thus it's a measurement of how far off from the reference titanium dioxide coating your test screen is.) So you can end up with gain numbers greater than one, which would imply that the screen is actually generating light - obviously violating the laws of physics!

With all that said, high-end screens (like the glass-bead-coated ones you see in movie theaters) can reach a gain of 2.5 compared to titanium dioxide, at least according to Wikipedia. (Note that this is measured perpendicular to the surface.) Based on that, a gain of 5 is probably not realistic.

Are you certain about the operation method? Because in the pictures the glasses appear to be nothing more than passive polarization filters - possibly with some minimal head-tracking hardware. I definitely don't see any embedded projectors in the pictures though. Also, the glasses are supposed to be wireless, so if there are embedded projectors, how are they powered? (No room for batteries either.) And don't forget that they'd also have to stream *two* video feeds via a wireless data link and decode it on the fly. Seems like a lot of hardware to fit into the admittedly stylish (but very small) frames.

Then too, if the projectors were in the glasses, you'd be constantly adjusting the geometric correction to get the "board" to perfectly overlay with the video image from the glasses. That's going to take some serious computation, and this is supposedly all running off a cell phone? Doubt it...

I'm guessing that it's actually designed to use an overhead projector running at 120 hz with a polarizing filter that swaps in and out every other frame to give you left-eye and right-eye fields. (Or a DLP-based solution to flip the polarity - result is the same.) Basically the same technology behind the passive 3D televisions from 10 years ago that you can't find anywhere anymore. :)

And this is assuming that it all actually exists and the video isn't just a teaser, of course. (Suspiciously, they want you to sign up to be notified when these will be available and all the news sites have the same teaser video with no further information on the system, so it could just be vaporware at this point.)

But at the very least, passive 3D displays that react to head-tracking for a single user are a solved problem, so I don't see anything about this product that is impossible. (Heck, they did it 12 years ago using a 2D display, and we demo'ed this at FLEM in Orlando that year...)

Adam
06-19-2019, 14:09
taxayy

The glasses are PHMDs (projective head mounted display) also known as HMPDs (head-mounted projective display).
These have existed since the 80s, but shrinking of reflective microdisplays into the sub-inch sizes and development of high power monochrome LEDs suitable for pico video projection has made it possible to make them much more affordably and in a much smaller form factor.

There are two reflective LCoS panels in this for each eye of the user. Someone had made a tear down video of one. DLP is too expensive in comparison. Additonally an LCD shutter layer is used on the glasses to reduce crosstalk between eyes.
The device was known before as CastAR and there were many 3rd party reviews of it. https://www.youtube.com/results?search_query=castar+ar

Since the beam is projected and reflected from a reflective polarizer towards the screen and then back through a wave plate to pass through the same polarizer, the beam is basically retro-reflecting almost exactly perfectly towards the eyes. This is not possible with a standard projector as the eyes are at an offset relative to the projector lens.

I don't know how much "Gain" this provides and was hoping to get an idea from others. A retro reflective screen has a very high gain inside a cone of a narrow angle, but inside the cone itself the brightness is not uniform based on the angle as well. Who knows how bright you can get if you beam the video almost exactly towards the eyes as in here unlike nearly exactly (a 5-10 degree deviation) like in some movie theater screens.
06-21-2019, 09:19
buffo

Quote:

Originally Posted by taxayy

The glasses are PHMDs (projective head mounted display) also known as HMPDs (head-mounted projective display).

How are you determining this? There is no information on the website, nor in any of the new articles I've found. (If you have links, please share...)

Given that they are wireless, I'm very curious (and more than a little skeptical) about how they're handling the power delivery, data link, and geometric correction issues in such a compact and seemingly lightweight package. Although I will admit that if it's a real product and it has decent battery life it could be a very attractive unit with uses far beyond simple tabletop gaming applications.

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There are two reflective LCoS panels in this for each eye of the user. Someone had made a tear down video of one.

How could someone have done a tear-down video on a product that isn't commercially available yet? Or are you referring to the failed CastAR product (which was *not* wireless)?

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DLP is too expensive in comparison.

Compared to what? We don't have a price on these things. Are you the developer?

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Since the beam is projected and reflected from a reflective polarizer towards the screen and then back through a wave plate to pass through the same polarizer, the beam is basically retro-reflecting almost exactly perfectly towards the eyes.

I think what you meant to say is that the light viewed *by the wearer* is essentially retro-reflected from the screen, and the polarization is also preserved which is needed to maintain the 3D effect. However, light is also scattered in other directions by the screen. Note that they don't make any claims about brightness compared to viewing angle.

I suspect that the screen on the table (the game board) is probably something very similar to the venerable glass bead movie screens used in theaters and not an absolute retro-reflector. (Allowing for the fact that a glass bead screen does have some retro-reflective properties, and this can be adjusted by varying the bead size.) And that would lead you back to the published maximum gain spec of ~ 2.0 to 2.5 I mentioned above.

Note also that the trade-off with glass bead screens is thus: More gain = narrower viewing angle (before you start to notice the brightness change). Given that this product would benefit from the widest possible viewing angle (while still preserving polarization), I suspect the gain is probably a lot lower than the maximum for glass bead screens. So probably something closer to 1.5.

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This is not possible with a standard projector as the eyes are at an offset relative to the projector lens.

On the contrary, it is possible. Ever been to a 3D movie? Ever notice that the effect works no matter where you sit in the theater, even though your viewing angle is offset from the projection angle?

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I don't know how much "Gain" this provides and was hoping to get an idea from others.

Again, the upper limit is probably somewhere in the range of 2.0 to 2.5.

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A retro reflective screen has a very high gain inside a cone of a narrow angle

A true retro-reflector would not allow the wide range of viewing angles displayed in the video. It would also greatly increase the cost of the screen. Until someone can test the actual screen to provide hard data, I'm going to assume they haven't invented a revolutionary new display screen material and are in fact using an industry standard glass bead screen material.

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Who knows how bright you can get if you beam the video almost exactly towards the eyes

Well, you can calculate it, if you're super curious, although it's not a very useful number. If you use a first-surface mirror, you can get ~95% of the incident light to come back. Slightly more even, if you can spend big bucks on said mirror. As to how that 95% reflectivity corresponds to gain, that depends on what reference standard you're using for gain, but it's safe to say that it would be much higher than the gain from a glass bead screen.

But what's the point? A mirror is essentially the worst case with regard to viewing angle. A perfect mirror only has one sight line to the projector, so it would be even worse than a retro-reflector in that respect. This is why glass bead screens are so common. They are a good compromise between a white painted wall (poor gain but very even brightness) and a mirror (near unity reflection, but only at a single angle so brightness is very uneven). At the peak gain (around 2.5) for a glass bead screen, you're dealing with just 10 to 15 degrees of usable viewing angle before the brightness changes are unacceptable. That's not wide enough for this product, so shooting for a gain higher than 2 is not practical.

Adam

PS: How about an introduction and maybe some background on what you're working on? Seems odd to just join a brand new forum and immediately start making technical assumptions, doesn't it? Or have you been here before under another name, perhaps?
06-21-2019, 13:55
taxayy

Why are you being a dipshit and acting as an interrogator? If you want to have a discussion that's not how you behave. I will respond to your questions but if you keep acting like this it may be the last time.

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Originally Posted by buffo

How are you determining this? There is no information on the website, nor in any of the new articles I've found. (If you have links, please share...)

Sure:
5th google result, https://www.roadtovr.com/tilt-five-a...g-board-games/
"Tilt Five appears to be the rebirth of CastAR (which itself was initially spun out of Valve) which reportedly shut down in 2017 before it was able to get its AR system to market."

The article explains how the device works too. if you search for CastAR you can find many articles and video interviews too.
The CEO of both companies (TiltFive and CastAR) is the same person too, that could have given you a hint as well.

For an official confirmation there's also a twitter comment I can dig up.
EDIT: here - https://twitter.com/tiltfive/status/1134510351767097344

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Given that they are wireless,

I never said they are wireless, I merely said PHMDs don't use an external projector and the projector is on the headset itself.

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I'm very curious (and more than a little skeptical) about how they're handling the power delivery, data link, and geometric correction issues in such a compact and seemingly lightweight package.

Google for "PHMDs" or "HMPDs" and you'll find dozens of articles and patents explaining how these devices work.
Or just type "CastAR" on Youtube: https://www.youtube.com/watch?v=3dltQ4-LYMk
https://youtu.be/zNWP4WOFvRs?t=470

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Although I will admit that if it's a real product and it has decent battery life it could be a very attractive unit with uses far beyond simple tabletop gaming applications.

Definitely, https://www.youtube.com/watch?v=7BEL3qy7BuY

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How could someone have done a tear-down video on a product that isn't commercially available yet? Or are you referring to the failed CastAR product (which was *not* wireless)?

Devices which are going to have 3rd party developers making content for them such as gaming consoles often have the "devkits" shipped to the devs before the commercial launch date so there will be content available for them on launch date... https://www.youtube.com/watch?v=zNWP4WOFvRs

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Compared to what? We don't have a price on these things. Are you the developer?

No, I'm not Jeri Ellsworth. I also want to again stress out that this is not an interrogation. Also, if I were Jeri I'd have many other places to shamelessly promote my product than a small forum.
DLP chipset prices have always been public, it's on their website. There are 5-6 manufacturers of LCoS panels you can find online and get bulk pricing via email. Not that hard to do.

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I think what you meant to say is that the light viewed *by the wearer* is essentially retro-reflected from the screen, and the polarization is also preserved which is needed to maintain the 3D effect.

No, the 3D effect on this is preserved with LCD shutters for each eye to reduce crosstalk from passive 3D. The light is polarized because LCoS panels cannot produce unpolarized projection beams. The TiltFive headset compared to the old CastAR design uses tilted (I assume this is where the name comes from) reflective linear polarizers and a quarter wave plate to first reflect the beam shining from above (as seen in the video I linked to) towards a tilted reflective polarizer. The beam then gets reflected towards the screen while being perpendicular to your eyeball, has its polarization rotated with a quarter wave plate, reflects from the screen and back, rotates from the same quarter wave plate and thus passes this time through the same tilted reflective polarizer. Doing so instead of shining the beam from above the eyes provides more Gain and is more efficient. This last part was confirmed in another twitter comment I can dig up.

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Note also that the trade-off with glass bead screens is thus: More gain = narrower viewing angle (before you start to notice the brightness change).

Narrower viewing angle means if you offset from the projector you get out of the center of the reflected light cone. With this the projector is strapped to your head and so you are always on the center hotspot.

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Ever been to a 3D movie? Ever notice that the effect works no matter where you sit in the theater, even though your viewing angle is offset from the projection angle?

Depends whether it is active 3d or passive 3d. Active 3d doesn't even need retro-reflective screens.
But you are talking about preserving polarization, not preserving gain. Retro-reflective screens preserve polarization even on the edge of their light cone. Two separate things.

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On the contrary, it is possible.

You are not actually reading what you are responding to. Again, the beam is basically retro-reflecting almost exactly perfectly towards the eyes. This is not possible with a standard projector. It is not possible because here, thanks to the reflective polarizer and how the projector lens is oriented relative to your eyes, your eyes are almost dead center of the reflected light cone, not at an offset like in a movie theatre. In a movie theatre the only thing dead center to the light cone is the projector's aperture.

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I suspect that the screen on the table (the game board) is probably something very similar to the venerable glass bead movie screens used in theaters and not an absolute retro-reflector. (Allowing for the fact that a glass bead screen does have some retro-reflective properties, and this can be adjusted by varying the bead size.) And that would lead you back to the published maximum gain spec of ~ 2.0 to 2.5 I mentioned above.

Yes, that is pretty much what the screen is. But as I explained the beam is reflected with a tilted polarizer and directed back to the eye at almost the exact offset of the eyeball. So your eye is almost dead center of the narrow light cone from the retro reflective projection screen, not at a slight offset like with video projectors. This provides even more perceived brightness from a retro-reflective screen. That's the whole point of this topic. I'm curious just how much it would be. I have not received my own devkit yet.
06-21-2019, 15:02
buffo

cypher0, Joec, taxayy, piydadorto, and shoujin walk into a bar...

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Originally Posted by taxayy

Why are you being a dipshit and acting as an interrogator?

Why are you resorting to defensive behavior and name calling on your 3rd post to the forum? Is that what passes for a discussion in your worldview?

Nothing in my post was an interrogation. That's you projecting. And still no introduction! Yet you presume to instruct me on social discourse.?. :rolleyes:

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I will respond to your questions but if you keep acting like this it may be the last time.

You can't be serious. This sounds like middle school courtyard drama! (Oh no! Whatever shall we do if another socially-inept sock-puppet who spent 5 minutes googling something to make him an expert gets upset when people counter his claims and ask for more information? Imagine how horrible it would be if they decided to leave the forum without first gracing us with a reply!)

Seriously: If you've got it all figured out already then you don't need anyone here on the forum, do you? So why are you here then?

Adam
06-23-2019, 05:25
Eidetic

Laser-based picoprojectors could keep the image focused on randomly placed screens in the environment, giving this technique a shot. Tiny LCoS displays, going out of favor because of OLED, make it easier to get nice images in them. I work with those from Compound Photonics, having the smallest pixels. PM me for more information about CP displays if you're interested.

I recall Jim Ferguson proposing retroreflecting screens with head mounted projectors in the '80s. The screen gain would be very high, maybe too high for good contrast because it has to also be highly polarization preserving. Especially if 3D content is desired. Good luck with that. This is probably one of those ideas that look great on paper but fall short in practical application. May be good for special uses though. Like secure viewing.
06-23-2019, 13:57
buffo

Quote:

Originally Posted by Eidetic

Laser-based picoprojectors could keep the image focused on randomly placed screens in the environment, giving this technique a shot.

Someone posted a while back about a small inflatable dome that you could use in your living room (seriously, like 2.5 meters - maybe smaller?), and if I remember correctly the use case involved a head-mounted pair of MEMS-projectors fed by a laser source. Coupled with the head-tracking 3D glasses (can't remember now if they were active or passive), it gave you a 3D view wherever you looked on the dome. And yeah, perfect focus everywhere. The headset was much less confining than the over-the-face googles like the Rift or Vive and offered a wider field of view to boot. Alas, brightness was an issue.

Thinking about the parent post some more, for this specific application (augmented reality for table-top gaming) I don't see a true stereoscopic 3D display being viable for more than a single user. If you have 4 people sitting around the table each user needs a render of the map from his or her own perspective relative to their position at the table. But you can't overlay those projections on the playing surface / screen as they will all blur together. Even if you used an overhead projector the 3D effect will still only work for people sitting on one side of the table.

Given that simulated 3D overhead augmented reality is already a thing (and relatively affordable), the fact that it hasn't been more widely adopted for tabletop gaming suggests to me that a true stereoscopic 3D display for tabletop gaming might not be the killer app I initially thought it might be. (Assuming this actually makes it to market, that is.)

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The screen gain would be very high, maybe too high for good contrast because it has to also be highly polarization preserving. Especially if 3D content is desired.

You can see this in the 3D cinema. Everything looks dim and gray, at least compared to the 2D version of the same film. Price you pay for passive 3D... Sigh. (That's with a screen gain of 2 to 2.5)

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This is probably one of those ideas that look great on paper but fall short in practical application.

Agreed.

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May be good for special uses though. Like secure viewing.

For a single user, I agree. (Or for multiple users if they "take turns" viewing the map. But that seems like a kluge.)

Adam
06-23-2019, 23:55
absolom7691

Unfortunately with "3D" there is really very little movement forward. It seems the industry is stuck at stereoscopic displays. That's the only game in town right now and has been for a long time. The only development is just perfecting was has already been the industry standard for decades. Until something new comes along, VR is going to remain a novelty. It's fun to play with for a time. Hell, I even own an Oculus but the novelty wears off after a bit.

Every time I see these projects come up, I always wonder about the small niche groups that that they will reach. Something needs to change or VR is always going to remain where its at now... just shy of mainstream with no real committed patrons.
06-24-2019, 00:05
White-Light

Quote:

Originally Posted by buffo

Given that simulated 3D overhead augmented reality is already a thing (and relatively affordable), the fact that it hasn't been more widely adopted for tabletop gaming suggests to me that a true stereoscopic 3D display for tabletop gaming might not be the killer app I initially thought it might be. (Assuming this actually makes it to market, that is.)

Adam

That's the bit I'm struggling with and wonder if it's why the original company folded. Why do you need a mat and a projector when you can simply project the whole game into a pair of VR glasses such as Pimax or Occulus?

Maybe this is an attempt to produce a cheaper version of VR by using AR and a cheap projector and mat instead of more expensive VR goggles. However, for the reasons Buffo has pointed out, I can't see this succeeding. The viewing angle is going to very much affect the brightness as huge amounts of light will be lost. If you bounce light off a mirror at 45 degress, most of it exits the mirror at 45 degrees in the opposite direction and is lost. Yes a glass bead mat might increase the amount reflected back by virtue of the 3D profile of the beads. However, I'd speculate a large proportion of the light will still reflect off in other directions and be lost, resulting in a dim image that fluctuates in brightness according to the angle of incidence. Therein, also lies a further problem - imagine 4 players sat around a table projecting the game. The light lost from the projection by the other players, especially the guy sat opposite is surely going to be reflected into your vision and cause some kind of flare or ghosting, unless they have done something trick with the polarisation timings so other players projections are either on the opposite polarity or fall into the brief switching period between polarities where no light is let through. That said, surely that would just introduce lag, even if it could be achieved.

Aligning with my 1st comment, it seems to me this is an attempt to reinvent the wheel, possibly in the aim of bringing a lower cost solution. However, the issue with reinventing the wheel, is you need to ensure it still comes out round.
06-24-2019, 05:05
buffo

Good discussion!

Quote:

Originally Posted by absolom7691

Unfortunately with "3D" there is really very little movement forward. It seems the industry is stuck at stereoscopic displays.

Agreed, although I'm at a loss to come up with another solution for 3D apart from a stereoscopic display. While the idea of capturing an interference pattern in a hologram to create a true 3D image is sexy as hell, I can't fathom a technology that could create such an interference pattern in real time at a high enough frame rate and resolution to enable 3D holographic video displays. Maybe they'll figure it out when we finally get our flying cars! :D

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Until something new comes along, VR is going to remain a novelty. It's fun to play with for a time. Hell, I even own an Oculus but the novelty wears off after a bit.

I have the HTC vive and I'm still enjoying it. I think the big problem with current VR gaming is related to the games themselves and not the technology. They're still looking for that "killer app" that will break the genre wide open. I thought Beat Sabre might be the one, but I think it's popularity has peaked. A decent Star Wars-themed first-person shooter would probably work though.

Regarding the tech: Flecom went to the IAAPA Expo in Orlando a year or two ago and they had a large room-scale multiplayer VR game room set up where players wore backpack-mounted gaming laptops and standard HTC Vive headsets. He said they had 30 people in a 40 ft square room all running around shooting one another in a "Call Of Duty" style game. From his description it sounded amazing. True, this isn't practical for a home setup, but they do have wireless options for the Vive now, and with the improvements in the controllers and the displays I think all that's missing is the right game. (Even though I'll admit that having enough open space will always be a challenge, unless you opt for a stand-in-place treadmill.)

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Originally Posted by White-Light

Why do you need a mat and a projector when you can simply project the whole game into a pair of VR glasses such as Pimax or Occulus?

I agree. If every player is wearing a VR headset the board itself isn't needed. But augmented reality *does* have a coolness factor all it's own, so maybe that's what they were going for? (And if so, then a single 2D overhead projector will give you pseudo-3D augmented reality for a lot less money.)

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I'd speculate a large proportion of the light will still reflect off in other directions and be lost, resulting in a dim image that fluctuates in brightness according to the angle of incidence.

Yup. For a typical high-reflectivity glass-bead screen, I think you'd be looking at a usable viewing angle (well, a cone) of about 15 degrees. If you reduce the brightness of the screen you can increase that of course, but now you run into two problems: one, the image will get dimmer as more light is scattered in other directions and is lost, and two, the polarization difference will start to smear together which will spoil the image quality.

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The light lost from the projection by the other players, especially the guy sat opposite is surely going to be reflected into your vision and cause some kind of flare or ghosting

Bingo. This, to me, is the biggest challenge of the entire setup. I just don't see how you could make this work with people sitting on opposite sides of the table and both projecting their own views down to the screen.

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unless they have done something trick with the polarisation timings so other players projections are either on the opposite polarity or fall into the brief switching period between polarities where no light is let through

Hmmm. So, hypothetically, let's take this in an entirely different direction: Assume you have LCD shutter goggles on each player (max of 4) and say you run the master overhead display at some ridiculously high frame rate - call it 240 frames per second. Further assume that the computer/graphics card driving this can calculate 4 separate 3D views of the board in real time based on head-tracking position data from each player's goggles. (Dual or Quad RTX 2080 with SLI should do it. Probably quad GTX 1070 SLI would be enough.)

Now you interleave the displayed frames like this: Player one - left eye view. Player two - left eye view. Player three - left eye view. Player four - left eye view. And now back to Player one - RIGHT eye view. And so on... Close the shutters on each set of goggles whenever another player's view is being shown. You would then get 30 frames per second for each eye, 60 frames per second for each player, and a total frame rate of 240 frames per second.

Each player would still have full view of the game board so the cool augmented reality feature is preserved (so you can use your favorite figurines or whatever) and as long as the overhead projector is bright enough you can still see well enough even with the LCD shutters closed for 75% of the time. You could even include "hidden" objects that are unique to each player. I think this would end up being more affordable than having 4 separate computers each driving a VR headset.

The main issue I see with this arrangement would be the super-brief exposure time for each player. (1/240th of a second per eye)
I know for a single exposure the response time is around 10 ms. This would be closer to 4 ms, but it's also a repeating image, so it might still work.
Would probably flicker like hell though. Sigh. Maybe it's not such a hot idea after all...

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it seems to me this is an attempt to reinvent the wheel, possibly in the aim of bringing a lower cost solution. However, the issue with reinventing the wheel, is you need to ensure it still comes out round.

Hehe! I like that analogy. Yeah, the more I think about this whole thing, the more I'm convinced that it's a non-starter. And to try to do it WIRELESSLY just adds that much more complexity. I doubt we'll see this in Best Buy anytime soon...

Adam
06-24-2019, 05:46
absolom7691

Quote:

Originally Posted by buffo

Agreed, although I'm at a loss to come up with another solution for 3D apart from a stereoscopic display. While the idea of capturing an interference pattern in a hologram to create a true 3D image is sexy as hell, I can't fathom a technology that could create such an interference pattern in real time at a high enough frame rate and resolution to enable 3D holographic video displays. Maybe they'll figure it out when we finally get our flying cars! :D

I agree whole heartedly with this. It's a shame that we only have stereoscopic displays because we'll always be limited by that.

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I think the big problem with current VR gaming is related to the games themselves and not the technology. They're still looking for that "killer app" that will break the genre wide open.

I halfway agree with this. The problem I see is that with VR, there needs to be so much more than just 3D visuals. The graphics are immersive and I will admit, when I first put on my Oculus, I thought it was cool as hell. The visuals were amazing and I felt like my head was in the place I saw. The problem was the rest of it... Not as immersive as I would like.

Yes though, the killer app has yet to surface. Robo Recall was one of best I played and given the number of games out there, I have only played a few that were any good. Unfortunately, this is like credit. You need get credit to establish credit but you can't get credit without having established credit. No programmers want to commit to the genre because it hasn't broken out yet but it can't until there are good programmers releasing titles....

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I think all that's missing is the right game. (Even though I'll admit that having enough open space will always be a challenge, unless you opt for a stand-in-place treadmill.)

I can get behind the thought here. Open space would be the one of the last pieces of the puzzle. Better haptic feedback would be great too. Of course, this comes back to the technology. Speaking of treadmills... skip to 9:10... https://www.youtube.com/watch?v=qh2UdRKNqH4 Looks promising.
06-24-2019, 06:35
Eidetic

Quote:

Originally Posted by buffo

Agreed, although I'm at a loss to come up with another solution for 3D apart from a stereoscopic display. While the idea of capturing an interference pattern in a hologram to create a true 3D image is sexy as hell, I can't fathom a technology that could create such an interference pattern in real time at a high enough frame rate and resolution to enable 3D holographic video displays. Maybe they'll figure it out when we finally get our flying cars! :D

Adam

Check out what VividQ is doing. https://www.vivid-q.com/
06-24-2019, 07:58
buffo

Quote:

Originally Posted by absolom7691

Robo Recall was one of best I played and given the number of games out there, I have only played a few that were any good.

I haven't tried that one yet, but based on a quick peek it looks really nice. I've enjoyed Raw Data a great deal even though the setting isn't nearly as photo-realistic.

First-person shooters are already well-represented in VR, but I'd like to see the technology used for other games. Imagine Roller Coaster Tycoon in VR, for example. (And no, not just for the ability to ride the rides.)

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Better haptic feedback would be great too.

Have you seen the new "knuckles" controllers from Valve? They don't really improve on the haptic feedback much (they use the same vibration feedback that the Vive controllers have), but they *do* allow for tracking of individual fingers, which opens up a lot of interesting options. I'm thinking about upgrading my VR setup this fall and will probably get a set of these controllers.

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Speaking of treadmills... skip to 9:10... https://www.youtube.com/watch?v=qh2UdRKNqH4 Looks promising.

I've seen a few different versions of the "treadmill of treadmills" design like that. Honestly though, I think it's probably too expensive for anything outside of a commercial video arcade. I think the passive systems with your feet sliding around on a polished bowl surface while you are suspended from an overhead arm (like you see at the start of the video you linked to) is probably the most cost-effective option. I think they could get the price of that rig down to a few hundred dollars at some point.

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Originally Posted by Eidetic

Check out what VividQ is doing. https://www.vivid-q.com/

Wow... I didn't think the hardware needed to generate a real-time diffraction hologram at 60 FPS existed yet. True, they're not calculating each point, but rather frame slices, so they are cheating a bit (it's not perfect), but from the videos I watched it sure looked good enough to me. Absolutely mind-blowing to think about all the calculations going on... (I found this overview presentation to be most informative.)

Limits appear to be the size of the spacial light modulator (LCoS), computational overhead, and cost. Guessing that illumination power is also limited based on the small size of the LCoS. I did see where they just got nearly 2/3 of a million dollars in venture capital though, so someone must think this idea has potential!

Would love to see this in person.

Adam
07-02-2019, 06:00
Eidetic

I saw it at Photonics West a few months ago. Very impressive, but also very limited eye box and field of view. I'm working with them on the former, but holographic light guides are not really a good solution for near-eye displays. That doesn't stop a company like Digilens from raising many millions over the years and recently to promote them. After 20 years of trying, nothing but prototypes and a single sale to Rockwell six years ago. 13 years of my career spent making those prototypes, but I digress.
07-03-2019, 08:41
buffo

Quote:

Originally Posted by Eidetic

13 years of my career spent making those prototypes, but I digress.

Seriously? I had no idea! I'd love to hear more about this sometime, as would several others I'm sure. (SELEM?)

Adam
10-27-2020, 18:23
CyberCityTOVC

Quote:

Originally Posted by buffo

Why are you resorting to defensive behavior and name calling on your 3rd post to the forum? Is that what passes for a discussion in your worldview?

Nothing in my post was an interrogation. That's you projecting. And still no introduction! Yet you presume to instruct me on social discourse.?. :rolleyes:

You can't be serious. This sounds like middle school courtyard drama! (Oh no! Whatever shall we do if another socially-inept sock-puppet who spent 5 minutes googling something to make him an expert gets upset when people counter his claims and ask for more information? Imagine how horrible it would be if they decided to leave the forum without first gracing us with a reply!)

Seriously: If you've got it all figured out already then you don't need anyone here on the forum, do you? So why are you here then?

Adam

First, I apologize for necroposting a thread that hasn't seen a post for like a year or so.

Now there are some misunderstanding how castAR / TiltFive glasses works.

Early prototypes in the earliest days of castAR used active shutters but during development, they had switched to a polarized projection and polarized lenses approach. This approach is still used in the TiltFive glasses which is a continuation of castAR's core technology.

The RR mat uses retroreflective fabric like used in safety vests. The light projected is return to origin within a narrow cone of returned light. Each lens of the glasses is polarized and so is the projection itself. They modified the projection path so that the light is returned to origin more centered to the user's eyes even more so than the earlier prototype and that involves some stuff that hasn't been discussed precisely how it works. The difference in the mat versus the fabric sheet of RR material is the use of passive dot pattern that is retroreflective and there is also a second camera that uses IR spectrum but on a different bandwidth than the tracking camera.... which is used for computer vision stuff which can be interesting in its own right.

Each player regardless if they are on the opposite side of the table or not is going to see what is projected from their own headset not the other players. The RR mat is not made from the same kind of fabric used on a typical projector screen.

Does it clear up anything? If there are more questions that you are interested in knowing more about castAR/TiltFive headset and all, please check out Tilt Five's website and Discord channel.