[HN Gopher] This is what Doom looks like on a holographic display
___________________________________________________________________
This is what Doom looks like on a holographic display
Author : ttflee
Score : 176 points
Date : 2021-04-19 08:54 UTC (14 hours ago)
(HTM) web link (twitter.com)
(TXT) w3m dump (twitter.com)
| hesdeadjim wrote:
| I've built a non-trivial prototype application for the Looking
| Glass, and once you are past the initial 'cool' moment the
| downsides start to rear their head:
|
| - Split a 4k signal into 45 view planes means the effective
| resolution sucks, bad.
|
| - Likewise, if your content is complicated at all you need a
| monster GPU because you are rendering your scenes 45 times _per_
| frame, meaning 45 times the draw calls.
|
| - Field of view is very limited
|
| - The amount of z-depth you can put content in without major
| blurring is much lower than even this video would indicate.
|
| - You need to design your scene so important content never
| reaches the edges or things look yuck.
|
| - Some patterns lead to artifacts like moire, and it can be hard
| to predict. Your content needs to work around this.
|
| - They are (understandably) very expensive.
|
| All that said, these things _are_ cool and would be a perfect fit
| for some use-cases. After the prototype I built was green lit for
| full production, the decision was made to ditch these displays
| for all the reasons above.
| staticautomatic wrote:
| Just use 45 GPUs. No big deal.
| deanCommie wrote:
| Uninformed outsider coming in with questions:
|
| 1) Isn't this just based on "naive" implementations? Surely
| there are optimizations to not have to render all 45 view
| planes at all times similar to how 3d rendering doesn't render
| scenes that are not visible until the character moves to change
| perspective?
|
| 2) The difficulty with layout and design doesn't seem that
| different from any 3d or game design challenges to make sure
| the person can't see the wizardry behind the curtain. Is it?
|
| I guess what i'm thinking is if you take an Introduction to
| Computer Graphics course, you can learn all the math, all the
| concepts, and all the abstract ideas about building 3D worlds.
| Then you try to implement them and you immediately realize that
| none of the ideas are performant enough to actually put into
| practice in a video game without MAJOR optimizations that on
| the surface seem 1/ Hacky, 2/ Extraordinarily difficult. We've
| been doing a range of them for 30 years. But some are only
| TODAY entering the mainstream despite being the simplest
| possible concept to explain to a student (ray tracing).
|
| Is it not the same situation with these kinds of displays (and
| other VR/AR)? We're in the super early stages and we need the
| John Carmack equivalents to identify all the super insanely
| clever optimizations to squeeze something practical out of
| them?
| toast0 wrote:
| > 1) Isn't this just based on "naive" implementations? Surely
| there are optimizations to not have to render all 45 view
| planes at all times similar to how 3d rendering doesn't
| render scenes that are not visible until the character moves
| to change perspective?
|
| _Maybe_ you could add head tracking to prune some angles,
| but if you were going to do head tracking, other comments
| have reports of good results without a lenticular setup. You
| 'd probably lose out on the multiple viewers aspect.
|
| I would think naively that there's some amount of work that
| could be shared between so many renders from nearly the same
| viewpoint. But that probably requires driver changes to make
| it available, I did find an article from NVidia about
| rendering four viewpoints in one pass, which might be
| applicable and help somewhat:
| https://developer.nvidia.com/blog/turing-multi-view-
| renderin...
| hnuser123456 wrote:
| The big difference is, unlike VR, you don't know where the
| viewer's eyes are, so you can't jump from 3D to 2x 2D so
| easily, you genuinely need a volume resolution instead of an
| area resolution. I suppose another way to think about it is,
| if they're splitting 4k into 45 planes, you're chopping 8.3
| MP into 0.184 MP (~430x430px) x 45 "pixels"/voxels of depth
| resolution. 3840x2160 pixels is the same number of samples as
| a 202x202x202 voxel cube. A 1000^3 voxel display equals
| 31600x31600 pixels of resolution, which is maybe possible to
| render at 30fps with a very, very simple application and a
| top-end GPU. 3000^3 = 164300x164300. We would need to rethink
| the entire graphics stack to figure out a "GPU" that could
| more efficiently "draw" to a hologram at high resolution and
| refresh rate. Maybe something like DLSS but 3D. Even then,
| the bandwidth will be insane. 1000^3, 1 billion voxels, * 32
| bits of color/alpha, is 32 gigabits per frame. 30fps would
| need 960 gigabits per second of bandwidth. Displayport 2.0 is
| 80 gbps. The fastest commercial optical transceivers are
| 100-400 gbps, although top-end GPU memory bandwidth is
| approaching 8000 gbps, good enough for 2000^3 @ 32bit @ 30fps
| or 1000^3 @ 240fps. The "GPU" will need to be tightly
| integrated into the display.
|
| It would be better if we could just have 3x 2D projectors
| that somehow interfere in a medium to display, but I don't
| know of a way to accomplish this. Not to mention none of this
| allows you to be inside the displayed content as VR does.
| hesdeadjim wrote:
| For some context, I've been making games across
| console/mobile/VR for about 12 years so I can provide
| (hopefully) some educated responses.
|
| For 1)
|
| - Their SDK implements this rendering strategy, so either
| they haven't been able to justify the effort for additional
| optimization, or (much more likely) there isn't a tenable
| general purpose solution that doesn't fall apart horribly in
| many circumstances. This latter point is true of many
| optimizations in games, they work because you can very
| narrowly scope them to what you are doing.
|
| - Frustum and occlusion culling are used, like you mention,
| to avoid rendering meshes that are off-screen. This isn't a
| panacea though, there can be significant CPU cost to doing so
| to the point where it can be _more_ performant to disable it.
| Case in point, I used Umbra occlusion culling in my VR game
| in only a few scenes because my CPU budget for 90 FPS was so
| small that the PS4 couldn 't keep up.
|
| - Those 45 planes are a series of slices that are _very_
| closely projected in space, so the odds that there isn 't any
| work to do is almost nil. Even more true when you consider
| dynamic scene elements, such as lighting and shadow casting.
|
| For 2)
|
| - All of the challenges present for 3D content creation are
| unchanged with this device, it just adds more on top (limited
| FOV, depth blur, and fringe blur). You can't wizard away
| seeing color separation at the border of the screen, it's
| just fundamentally the hardware's limitations.
|
| Another example, the PSVR headset's OLED panels cause a
| purple blur to happen on edges that have too much light/dark
| contrast. The solution? Call an API and change a floating
| point "base brightness" level for the headset, or change your
| lighting -- for _each_ level (this is Sony 's
| recommendation!). Entirely game and scene dependent, and not
| something that an automatic solution could accomplish.
|
| - Some of the "magic" techniques invented for VR performance
| may have the possibility to be applicable (skipped frame re-
| projection, foveated rendering), but those are based on the
| math between two camera projections not 45.
|
| - Any improvements that could be created by a Carmack-level
| person are going to be market driven. The population of
| people that fit in that category would have the opportunity
| to work on whatever they want, and VR was compelling to many
| of them because of how damned cool it is (was?). By
| comparison, this tech is a novelty that a regular consumer
| will probably never see.
| boboche wrote:
| This is autostereoscopic, not holographic. It is however really
| nice, 10 yrs ago we were playing Quake on a WowVx display from
| Phillips when not working on autostereoscopic digital signage
| content. Phillips stopped with as3d and spun off Dimenco which
| are also selling As3d products, newsight, tridelity, and a few
| others are around... but all of this is NOT holography. Its high
| res display with a lenticular sheet splitting viewpoints.
| mdip wrote:
| Thanks for the info -- I had assumed this was the case[0].
|
| When I looked at the animations/video, I thought it was _really
| slick_ and as I read more about the tech it appeared to be as I
| expected, but I 'm not sure if I should be disappointed by
| that.
|
| I think it was quite intelligent for the company to offer a
| smaller, relatively inexpensive ($249 early-bird isn't bad)
| display because I fully expect it'll be impossible to properly
| evaluate the quality of the tech without actually seeing it
| live. The few times I've played with some of the more exotic
| screens (even oddball LCD screens like the promising, but brief
| IGZO LCD panels) are very difficult to evaluate. The videos are
| usually far from what it looks like in-person (and I'd wager
| about 75% of the time, the video makes displays look worse than
| it is).
|
| I'm curious if you can speak to the down-sides of doing things
| this way. Were this screen a "real holographic display" but
| with the similar constraints[1], would it be substantially
| better? From the videos, I get the impression that this screen
| can only display 3D within the bounds of the "box", so if a
| real holographic display behaved similarly, what could it do
| that an autostereoscopic screen cannot?
|
| I'm curious because I was left behind during the 3D craze (that
| disappeared, as I predicted, a few years later). I can handle
| about 30 minutes of 3D-glasses before I start getting the early
| symptoms of Migraine. I was hopeful when the TVs came out that
| I might be able to watch Avatar[2], finally, but I tried
| various sets with different types of 3D glasses
| (active/passive, I recall?) and they felt more uncomfortable
| than at the theaters[3]. I've never been diagnosed with lazy
| eyes/other eye problems, but I feel like my eyes go cross-eyed
| with the glasses on.
|
| I'd have to see this, physically, to be comfortable with buying
| it. At the price-point of their smaller option, that's getting
| pretty close, though. If they had a very convenient/complete
| return policy, I'd probably check it out.
|
| [0] That's not to diminish the value of the comment, I had only
| assumed it was some form of "Glasses-free 3D", but know nothing
| about the tech or how it works.
|
| [1] As in, the dream is a "projector like" screen where a
| hologram could just be displayed in an arbitrary location in a
| room, is out.
|
| [2] I have not seen it, yet. When it had finally died down in
| theatres, I had read that the story was "not very
| interesting/creative" and "kind of dumb". This was supported by
| the fact that everyone I know who went to see it told me
| _nothing_ about what the movie was about and not one of them
| mentioned anything they liked about the "story". I think the
| best summary I received was from a close friend who said "I
| left the theater and 'the world' seemed a little less real" and
| I was interested to see the result of this camera that was
| invented for the purpose of filming that movie, but I haven't
| seen a second of it, yet.
|
| [3] I thought it was normal to feel "off". I call it "almost
| dizzy" because I don't feel off balance, it just feels like it
| takes an amazing amount of effort to pinpoint objects with my
| eyes -- screen or otherwise -- with any kind of 3D glasses on.
| I wear a very low prescription pair of glasses (not required
| for driving, I'm nearly 20/20) and other than really cheap
| sunglasses, I generally have no difficulties otherwise.
| icegreentea2 wrote:
| Like other people have said, this looks like a Looking Glass dev
| unit or something.
|
| And here's a Linus Tech Tips video of it:
| https://www.youtube.com/watch?v=-EA2FQXs4dw
|
| They have some good footage (though obviously it's setup as a
| hype reel too).
|
| Edit: Skip to follow for "beauty shots": 4:45 and 8:50. 6:12 for
| funky shot of the 'flattened' image to give you a sense of what
| 'trick' they're playing
| ekianjo wrote:
| Cool but technically looking glass is not an holographic display.
| bredren wrote:
| Neither was Time Traveller, but it was also cool.
|
| So far "holographic" seems to describe the experience of the
| viewer more than a technical spec.
|
| https://en.wikipedia.org/wiki/Time_Traveler_(video_game)
| tito wrote:
| Incredible stuff! I first saw Looking Glass Factory [0] at Maker
| Faire in San Mateo around 2016. It was simple back then, probably
| 64 x 64 pixels "display". Imagine a bamboo garden made of 64 LED
| strips standing up, about 3'x3'x3' cube. Playing screensaver type
| light displays, entertaining at low res.
|
| Then I saw a more recent version at a coffee shop in Providence.
| They're up to legit resolution now, and as a poster said, the
| light is split so all you're doing is moving your head. No head
| tracking/whatever.
|
| It's one of those things that's tough to "get" without seeing
| yourself. Feels like a definitive piece of the future. I joined
| their Kickstarter awhile back as well.
|
| Go Looking Glass crew!
|
| [0] https://lookingglassfactory.com/
| elyobo wrote:
| > This is not available to you
|
| -\\_(tsu)_/-
| tumetab1 wrote:
| That's a twitter bug/feature that requires one or more browsers
| refreshes to find and show a tweet.
| MaxBarraclough wrote:
| This seems to happen a lot. Not the first time I've seen this
| crop up in an HN thread.
| elyobo wrote:
| Thanks, not one I'd encountered.
| Black101 wrote:
| Probably happened at least 20 times to me... the first time
| was probably a year ago...
| isoskeles wrote:
| I've always wondered why it happens. Best guess is they
| have a short timeout like 1s to retrieve that content.
| alvarlagerlof wrote:
| I wish people would stop calling these holographic
| forgotpwd16 wrote:
| Why?
| f6v wrote:
| I guess that's not how people imagine holograms based on sci-
| fi.
| chmod775 wrote:
| Because it's a lenticular screen.
| mnw21cam wrote:
| Because they aren't holograms. A hologram is "a recording of
| an interference pattern which uses diffraction to reproduce a
| 3D light field" [0]. This is something completely different.
|
| [0] https://en.wikipedia.org/wiki/Holography
| monsieurbanana wrote:
| This is... way cheaper than I thought it would be at $250(pre-
| order price?).
|
| But I don't understand how it works. Seems like... head/hand
| tracking? But then why the weird-looking screen?
|
| A bit disappointed, at first I thought it was something similar
| to those cards we had when we were kids, that change image
| depending on which angle you look at them (forgot the name).
|
| Edit: seems like it's a bit of both:
| https://docs.lookingglassfactory.com/KeyConcepts/how-it-work...
|
| Edit2: Okay so it does work like the cards we had when we were
| kids. The screen shows 45 different views of the scene at once.
| I'm back at being non-disappointed.
| kgwxd wrote:
| Lenticular photos
| https://en.m.wikipedia.org/wiki/Lenticular_printing
| frankenst1 wrote:
| The display shown in the video is the 15.6" display which costs
| $3,000 (https://lookingglassfactory.com/product/15-6).
| gaudat wrote:
| It takes probably less than $300 to DIY this from a off-the-
| shelf 15.6" display and a piece of dot lenticular sheet...
| andybak wrote:
| Which would look entirely different.
| monsieurbanana wrote:
| Me: Mom can we have Dropbox?
|
| Mom: We have Dropbox at home
|
| Dropbox at home: ftp + curlftpfs + svn
| mdip wrote:
| I laughed so hard when I read this, but then I realized
| something. Dude, you have a _really cool mom_.
|
| But I'm "that Dad". For home-related projects, about 25%
| of the stuff I replace with "home-built" ends up being
| the things my kids show off to their friends[0]. The
| other half is duct-tape and rubber bands. Unfortunately,
| the duct tape exists in the worst places -- like DHCP,
| and my routers, so while they don't require extra effort
| to use, they flake out on some of their devices[1].
|
| My favorite is when I have to be called over to explain
| that, no, Son is not lying us doing that ourselves. He
| used to walk into his room and hit a few keys on the
| remote, which would trigger Plex to play a song, dim the
| regular lights and enable some really slick music
| visualizations. Hit pause/quit the app and the room goes
| back to previous state. If his phone started ringing, the
| app would auto-pause[2] and play-back after the phone
| returned to idle state.
|
| [0] It goes something like: "Son: Can I buy this
| (overpriced) LED/gaming PC thing?" and usually ends with
| me saying "... or, we can buy $10 worth of things I don't
| already have and make something that when you're friends
| as 'where can I buy that', you can say 'You can't, but I
| sell them for (overpriced) if you want to buy one!'". .
|
| [1] Recently better -- ESP8266 devices and Android
| devices didn't play well with one of my DD-WRT based
| routers.
|
| [2] Home Assistant and Android allowed me to read phone
| state. It worked but there was _horrible_ delay and after
| a phone update, it just broke entirely, causing it to
| interrupt playback constantly. I ended up wiping out
| every related piece of that automation with the intent of
| doing it right (with a bluetooth sensor in his room which
| would allow me to trigger actions when he arrives /exits
| the room) but haven't completed that, yet.
| supermatt wrote:
| Isnt this exactly how it works (a lenticular lens)? Why
| would it look different?
| andybak wrote:
| I've used a Looking Glass and it doesn't look like a a
| lenticular display. It looks closer to a hologram
| (despite the fact it's not.)
|
| The image appears suspending inside the block of glass
| and responds sufficiently well to head movements to be
| convincing. You can't see the giveaway "ruled lines" that
| lentincular sheets have.
|
| Once you know it's not truly holographic it becomes
| fairly obvious and you notice that up/down doesn't
| provide any depth (only left/right) but the effect is
| convincing and magical at first.
|
| So although it might be lenticular in principle - it's
| far from what you could achieve with your proposed
| method.
| mdip wrote:
| Thanks for the information -- this was one of the
| concerns I expressed in a previous comment. It's going to
| be _very_ difficult to evaluate this product via video.
| The videos /animations look _so good_ that I had a hard
| time believing that the display performs that well in-
| person[0].
|
| I can understand how this might really look a bit better,
| now, with the clarity on the left/right vs up/down depth
| (I recall reading something about depth perception that
| makes this less important, but I don't recall
| where/when), so it's sounding promising.
|
| [0] I'm not saying it doesn't -- this is just based
| simply on the fact that I have yet to see one that does
| (and, in fact, if this isn't the technology I think it
| is, I haven't seen one _at all_ ).
| supermatt wrote:
| Is not really my proposed method, it's just how I
| understood them to work. IIRC they had a diagram with the
| original models that showed the lens, and also labelled
| things like a diffuser, etc. I'm not sure how much the
| technology has changed since their last generation.
| monsieurbanana wrote:
| ... Ah.
| [deleted]
| teekert wrote:
| Cool, but, it looks exactly like watching a display with a Wii
| remote on your head [0, 2007]. What's so special? Is it actually
| 3D this time?
|
| [0] https://www.youtube.com/watch?v=Jd3-eiid-Uw
| mattowen_uk wrote:
| > _https://www.youtube.com/watch?v=Jd3-eiid-Uw_
|
| I did this at the time. I downloaded his Wii app that shows the
| little red/white discs, and bought a battery powered Wii-bar
| thing that had the IR leds in it and strapped it to my head.
|
| Can confirm, the 3D effect is 100% spot on, even the smallest
| move of your head caused the display to adjust perspective and
| your brain is totally fooled into thinking the Wii display is a
| just a window into a 3D scene.
|
| tbh, it was the only cool thing I actually did with my Wii!
| SirHound wrote:
| Surely the depth effect only worked with one eye closed?
| wffurr wrote:
| Nope, works with both eyes.
|
| Your brain takes a lot more cues for depth than
| stereoscopic vision. The way the perspective changes as you
| move your head around is sufficient even for a flat
| display. It's uncanny.
|
| Only works for one person though. If you stand at an off
| angle to the sensors, there's no effect at all.
| RHSeeger wrote:
| Its amazing how the brain works...
|
| I am very cross-eyed at the moment (surgery resulted in
| both my eyeballs moving) and require a little plastic
| "stickon" that goes on the left lens of my glasses; which
| has prisms to redirect the light so that both eyes are
| looking in the same direction (prisms are fairly normal;
| it's the _amount_ of correction I need that is abnormal).
|
| The correction on the left lens is so bad that looking
| through it is completely blurry (with lots of rainbows if
| I'm looking towards a light). However, when looking
| through my glasses with both eyes, everything appears
| normal. I can see in stereo (which I cannot do w/o the
| correction) and everything is in focus. There is still
| _some_ rainbow effect.
|
| So, my brain is taking the "clear image" from my right
| eye and overlaying it with the distance information that
| the left eye adds to that... but ignoring the blurry
| image from the left eye completely.
|
| Honestly, I find it mind boggling.
| cbm-vic-20 wrote:
| And that video is over 13 years old! Too bad this idea didn't
| catch on more widely.
| Wowfunhappy wrote:
| It doesn't seem to exist anymore, but I had a variant
| (literally same graphics) on my iPhone a decade ago. No
| fancy headgear and the effect was just as good--but instead
| of moving your head, you held still and tilted your iPhone.
|
| Apple later added the effect to the homescreen in iOS 7,
| but much more subtle.
| mrguyorama wrote:
| TrackIR is a consumer product using the exact same tech for
| headtracking in video games. I think it might actually be
| older than the Wii
| mdip wrote:
| Thanks. I just created a nice storage box for my Wii, got
| everything organized and put it on the bottom of a large pile
| of things to sell.
|
| This sounds way too interesting, so I'll be doing some
| digging, apparently. Any idea if this would work effectively
| on a large projector screen?
| Jemm wrote:
| TrackIR and variants are quite popular for simulator type games
| like flight simulator or truck simulator. They let you look
| around in the game just by moving your head.
| dividuum wrote:
| Hm. I haven't really looked too deep into TrackIR, but I
| always thought it tracked your head movement to simulate head
| rotation within the game. So you could look around more
| naturally. The linked Wii "tracking" demo used the tracking
| to find your position relative to the display to change the
| rendered perspective accordingly. Does TrackIR also allow
| this?
| winthrowe wrote:
| As a TrackIR user, it feels to me like it should be
| possible to do something like this with the 6dof
| headtracking data from TrackIR, but basically nobody uses a
| 1-1 mapping that would produce a camera trick like this.
| mrguyorama wrote:
| TrackIR DOES do this. In flight simulator, with full
| 6dof, you can move your virtual head around and look
| under and around things
| runawaybottle wrote:
| Well, if it's as simple as head tracking with a IR emitter on
| your headphones or the like, then I'm a little surprised first
| person shooters don't enable peeking around corners with head
| motion.
| xwolfi wrote:
| It doesn't seen to be, or rotating the thing with a fixed
| camera wouldn't produce the effect, I guess ?
|
| https://lookingglassfactory.com/tech
| mnw21cam wrote:
| I'm just going to link
| https://www.cl.cam.ac.uk/research/rainbow/research/autostere...
| here - an autostereo display that was working way earlier than
| that. "The first displays were built in the late 1980s and
| early 1990s". They worked by projecting different images out to
| different horizontal areas in front of them, so your right and
| left eyes would see a different image, you could move your head
| and see around objects, and multiple people could look at it
| and see an appropriate view for their position.
|
| Not sure if they ever ran Doom on it though.
| detaro wrote:
| > _What's so special?_
|
| That it's not based on head tracking, and in a product you'll
| be able to reasonably buy.
| jcelerier wrote:
| with an holographic display two persons looking from different
| angles would see the image corresponding to their angle
| mdip wrote:
| I think that sums it up pretty perfectly. It's the single
| reason I watched the video and my first thought was "there's
| no way that works that well"
|
| From the comments, here, it sounds like it might. There's
| some interesting applications, here. Thinking back to last
| night, it would have been really nice if when I was looking
| at the split-screen in my driving game with my kids, my own
| corner had that kind of depth to it. Hell, driving/flying
| games, in general, suffer from realism issues due to not
| being able to faithfully produce the effect of looking out a
| window.
|
| Doing this on a larger screen (and throw in a transparent LCD
| after you work out how to bend all of _this_ into _that_ ,
| assuming it can be done) and you could have a light-switch
| that changes the scenery from "outside" to "outside somewhere
| else"[0].
|
| [0] I remember seeing that in Back to the Future II as a kid
| and thinking it'd be really nice to have on a cold, gloomy,
| February day in Michigan.
| 0-_-0 wrote:
| Cool, but it's not using the correct FOV to make sure the
| viewer/eye is at the focal point. That would look way cooler,
| I've seen a demo like that before. You get the impression you're
| looking through a window to another world.
|
| Edit: the video linked here by _teekert_ does it correctly
| supermatt wrote:
| i love these displays, but the smaller one feels too small for
| anything other than a photo-frame, and the large(r) one is CRAZY
| expensive (and still too small...)
| Black101 wrote:
| The next wall hackers
| mdip wrote:
| Every hacker's basement[0] (with enough money) is going to be
| walls of these. Can't wait for the first take on a holodeck[1]
|
| [0] Garage/shed/lab
|
| [1] Not implying this would come even _close_ , especially not
| being a "true hologram", but it'd still be the closest we could
| probably get with current tech outside of headgear.
___________________________________________________________________
(page generated 2021-04-19 23:02 UTC)