[HN Gopher] Tiny volumetric display
___________________________________________________________________
Tiny volumetric display
Author : ttesmer
Score : 846 points
Date : 2023-12-02 12:23 UTC (10 hours ago)
(HTM) web link (mitxela.com)
(TXT) w3m dump (mitxela.com)
| imdsm wrote:
| I love this. Must be a lot of fun to work on it!
| twoodfin wrote:
| One of those brilliant ideas that seems obvious in retrospect.
|
| Given that the results are so compelling even when pulled
| together by hand out of relatively primitive discrete components,
| I'm wondering why we shouldn't expect to see full color, high
| resolution versions from every random 7-letter drop shipper on
| Amazon next Christmas?
| crazygringo wrote:
| It's not a new idea -- they're called swept-volume volumetric
| displays, and they've been around for a long time [1].
|
| But they're mostly kind of just toys. When you're limited to
| transparent glowing surfaces and you can't even touch them,
| there's really not a whole ton you can do. You can see a much
| larger non-spinning version made of LEDs suspended on cables
| [2] and it's very cool, but the novelty kind of wears off after
| a while, and you realize it's not the kind of display you're
| going to use for anything productive.
|
| If you actually want real 3D visualization that can render
| anything at high quality and that you can interact with, it
| seems like VR/AR headsets are the way. (Though there are also
| the new 3D monitors that don't require glasses, but not a lot
| of people have gotten to see those in person yet.)
|
| Maybe there's some kind of toy you could make with them to sell
| on Amazon though? Not really sure if there's a "killer app" for
| these things.
|
| [1] https://en.wikipedia.org/wiki/Volumetric_display#Swept-
| volum...
|
| [2] https://www.ledpulse.com/
| djmips wrote:
| For [2] it does not look swept. Appears static.
| jessriedel wrote:
| Yea, specifically it looks like the LEDs suspended on
| threads and statically fill the volume.
| 8n4vidtmkvmk wrote:
| They said as much.
| noduerme wrote:
| The killer app is clearly sending messages via R2-D2.
| crazygringo wrote:
| This... is true.
|
| It would actually make a _fantastic_ Princess Leia message
| toy!
| m3kw9 wrote:
| for a 32 inch display, you gonna get a motor that may need to
| spin like a mofo in an area of pi*32^2.
| nine_k wrote:
| The display needs to be pretty strong physically.
| tromp wrote:
| The centering issue could be solved by putting two led boards on
| top, back to back.Perhaps one board could shift the leds over by
| half to create an interlacing effect while doubling resolution.
| swayvil wrote:
| There's gotta be some way to replace the rack-of-leds-spinner
| with something lighter. Mirrors? Acrylic light pipe matrix?
| lstodd wrote:
| I wonder if it would be simpler to just spin two phone
| screens glued back-to-back. You get higher resolution in
| about the same weight. Bandwidth would be a problem though.
| mistercow wrote:
| The fundamental problem is refresh rate. If you have two
| phones that refresh at 240Hz (the fastest I know of), and
| you want your frame rate to be 12 Hz, you'll still only be
| getting 20 refreshes per 180 degree rotation. So your
| angular resolution will only be 9 degrees. Assuming you use
| portrait mode, that will make your outermost voxels ~5 mm
| arcs.
|
| And even there, 12 Hz is probably pushing it in terms of
| flicker.
| lstodd wrote:
| Yeah, well, that's not going to work. Interesting problem
| all the same.
|
| For a 1 meter diameter and height cylinder at 60Hz voxel
| refresh and say 1mm resolution at the edge one would need
| the plane rotating at obviously 3600 rpm, and edge pixels
| switching at about 380KHz. Since rgb is nice to have
| that's 10 gigabit for a somewhat coarse display. Nothing
| impossible, but not a DIY territory yet.
|
| I think one'd want the LEDs either on the receding or the
| advancing halves of the plate, depending on which is best
| for the cooling -- not all on the same side or on both --
| that would be just a waste.
|
| Or even just on one half of the plate, the other being
| just a countermass. This way cuts the bandwidth in two.
| CrazyStat wrote:
| > For a 1 meter diameter and height cylinder at 60Hz
| voxel refresh and say 1mm resolution at the edge one
| would need the plane rotating at obviously 3600 rpm
|
| The edge of such a display would also be moving at
| several hundred miles per hour, which creates it own
| whole set of problems.
| dsr_ wrote:
| Note that in your hypothetical 1m 60Hz display, the edge
| of the cylinder is moving at 422 miles per hour. I'm
| going to recommend an evacuated transparent bell jar for
| safety, at a minimum...
| lstodd wrote:
| Of course it has to be evacuated and maybe filled with
| helium or something less viscous than air at low
| pressure; this has to be calculated wrt the heat
| rejection from the leds. Also centrifugal force shearing
| and tearing off components, imagine the fun.
|
| All in all, this is what makes it interesting, no? 1x1
| meter holo tank, not those tiny Voxon shakers.
| mistercow wrote:
| I wonder if anyone has built multi-speed "layered" swept
| volumetric displays. For the center part, you would still
| just have one screen, but as you go further out, you'd
| have "spokes", so that each screen only has to sweep a
| small angle (and roughly constant distance) during a
| frame, so that it rotates at lower RPM, and has to update
| fewer times.
|
| You would still need a bare minimum of 1-2 kHz, and a
| _lot_ of screens, and balancing every layer would be
| super difficult, but I don't think anything about it is
| fundamentally impossible with current technology.
| zrezzed wrote:
| Not exactly sure what the details, but there high
| quality, commercial products that are probably doing
| something like this: https://voxon.co/products/
| swayvil wrote:
| Doesn't it have to be transparent?
|
| Are phone screens (minus the phone etc) transparent?
| jacquesm wrote:
| Why do you think the weight is the problem?
| swayvil wrote:
| Because EVIL = RPM X WEIGHT.
|
| And we can't reduce RPM.
|
| Get it light enough and you don't even have to center it
| that good.
| jacquesm wrote:
| Ah ok, I figured that by casting the whole thing in resin
| and adding a top bearing it would get rid of the air flow
| issue completely at the expense of some extra work and a
| bit less light output.
| o11c wrote:
| Or just ... don't center, and change the math to acknowledge
| that the LEDs aren't centered?
| yafbum wrote:
| There's another similar thing needing correction, which is
| that the LEDs near the center sweep a much smaller volume
| than the ones at the edge, and should be dimmed in order to
| yield equivalent luminance. LEDs describing tiny circles very
| close to the center would need to be dimmed a lot since
| they'd essentially be stationary. Wouldn't it be better then
| to sweep slightly larger circles at the middle anyways?
| Tenemo wrote:
| I would pay $200+ for a bigger (50x50?), rugged, RGB version of
| this that you can make to display different images without
| coding.
| leetbulb wrote:
| It's not volumetric, but it's still really cool and may fit
| your use case https://spinprojector.com/
| alright2565 wrote:
| Only place I've seen these before is at the Atlanta airport,
| where they use them to show a 3d-animated sign to remind you
| not to bring your gun through the security checkpoint.
| wongarsu wrote:
| I sometimes see them at trade fairs as an eye catcher. With
| the right background you can get a pretty convincing 3d
| effect out of them despite the "display" only being 2d
| crashmat wrote:
| I saw some poi that worked like that. The performer did a
| very good show with them
| swayvil wrote:
| This is tight. Presently working on a list of uses.
|
| Need one the size of a 5gal bucket.
|
| As it is, I'd stick one on my gimcrack cabinet.
| ilaksh wrote:
| https://youtu.be/CCuybyAO8fs?si=xBLYy5zKEEcloqeA
| leetbulb wrote:
| Wow this one is cool. First time I've seen it. Reciprocating
| screen? How the hell do they get it to move that quickly?
| That is very high energy.
|
| Edit found another video showing it starting up
| https://www.youtube.com/watch?v=SMz4bJA47Js
|
| Now that I think about it, I suppose if you match the
| resonate frequency of the display component and its carrier
| it should be fairly efficient. Really cool stuff.
| eichin wrote:
| Other videos say that the bubble is just to protect the
| screen because (unsurprisingly, I would) people try to
| touch it - so it's not evacuated; doesn't that mean it's
| going to be a fairly loud 30hz speaker, effectively? (or is
| it just not well coupled because "speakers need to actually
| be designed" and it's not that bad in practice?)
| swayvil wrote:
| It's so smooth!
| ilaksh wrote:
| https://youtu.be/mxyw6LkAtiQ?si=xK0x8-rEoG0KvzPp
| fortran77 wrote:
| Having electronic candles that display a real 3D image of a
| burning flame seems like a great use for me! People would love
| these for outdoor "candle" displays.
| wvh wrote:
| Creative. I probably have the persistence and interest to pull
| something like this off, but I lack the fantasy to come up with
| such cool projects. Luckily there's the internet to see what
| impressive stuff people come up with.
| mistercow wrote:
| Tom 7 mentioned a thing in one of his videos, which is to keep
| a list, and write down every idea when you think of it,
| regardless of how stupid it is. Winnowing is for later. That
| way, when you have the energy to work on a project, you don't
| have to waste it on coming up with an idea.
|
| It really makes a huge difference in what you can get done with
| side projects. You probably have more interesting ideas than
| you think you do, but if having them doesn't line up with
| having the time and energy to act on them (or even to just
| expand on them), they'll fade away.
| gregsadetsky wrote:
| 100%. And the "weird" (not weird -- useful!) thing that
| happens with time is that once you start writing down ideas
| (and you should definitely note pretty much all of them -
| regardless of how good/bad they seem), your mind gets into
| "having more ideas" mode... You sort of get a second wind -
| or more accurately, you start developing your "what if"
| muscle. And the stronger it gets, the more "what if"s you'll
| have. And some of those will 100% be really really good
| (whatever good means to you).
|
| It's also ok to have really """bad""" ideas. They're always
| funny to read back (a month/year) later. They're fun to share
| with friends and strangers. And sometimes they lead to good
| ones as you think about what made you think the bad ones were
| bad in the first place.
| djmips wrote:
| But when you write it down - please include more than two or
| three words - because it's hillarious to come back to a list
| when a lot of time has past to see an idea written simply as
| 'The pope of physics' <- from my own list. I have no idea
| what I was thinking...
| BenjiWiebe wrote:
| I have the inverse problem. Do you have any advice for me?
|
| I have no problem coming up with, and remembering, cool
| projects. I just rarely have the energy or the lasting
| enthusiasm to actually follow through.
| gnramires wrote:
| Creativity can be trained just like any other skills! :)
|
| I second taking note of stuff; like most things, genuinely
| practicing means you will get better.
|
| Something that's also overlooked often is (1) Technical
| knowledge, (2) Methodical invention (3) Motivation!.
|
| Technical knowledge helps you know which projects are possible
| (or just economically feasible), and map the roadblocks on the
| way; impossible inventions are not really useful.
|
| Methodical invention means methodically looking at things
| instead of just randomly inventing. So you analyze a problem,
| like: (a) I want to make a volumetric display, (b) I want to
| bring (virtual) 3D objects to life. Notice the subtle
| difference between the two. Volumetric displays (a) can range
| from a lightfield display, which is a very elegant theoretical
| foundation (and can be realized in a number of ways), to
| volumetric persistence-of-vision displays like the own shown
| here. It's likely you will eventually arrive at whatever
| solutions are possible when you deeply research about a problem
| domain. Bringing a 3D object to life (b) can mean anything from
| digital fabrication, VR glasses, haptic interaction, robots,
| and more. It's a much wider problem domain.
|
| Motivation is also really important. Understanding why you're
| inventing, and what you what you want to bring to life is also
| significant. Are you going to bring people joy, is it just very
| cool, is it a useful medical device that can save lives, etc..
| Focusing on worthy subjects is also something you can study and
| that will really increase how good you are at inventing. Of
| course making stuff just because [we like it] is also important
| and valid :)
|
| And for me the most important part is to have fun while you're
| at it...
| gnramires wrote:
| I forgot to add: it's unlikely anything you come up with
| (while trying to develop your creativity) is going to be
| legitimately useful or even fun. It's like expecting to play
| a violin like Hillary Hahn (or <insert skilled musician>)
| after you've just picked it up. But the time to play an
| instrument so that at least you can tolerate your own sounds
| and have fun is much shorter -- and frankly, necessary I
| think not to give up before you can play really well (if that
| matters at all).
| tarikjn wrote:
| I have the reverse issue, I am constantly coming up with
| creative ideas, so that by the time I am done building idea A
| prototype v1 (something like what you see in this video) or v2,
| idea B comes along and distracts me from seeing idea A all the
| way through. And when the persistence and discipline is there,
| bills need to be paid, and the distraction is not idea B, but
| merely some mundane work.
| jacquesm wrote:
| I solve it like this: when at work the soldering iron is in
| the garage. That little barrier helps a lot when temptation
| to tinker strikes.
|
| One thing that I really like about this site is that the
| creator spends a ton of time on documenting it all. I am
| usually so busy with projects I don't get around to it.
| Another problem is that, especially for larger projects, that
| you need to store and maintain them. And that gets old pretty
| quickly when you're lugging around 200 pound windmills and
| such.
| Retr0id wrote:
| It would be hard to manufacture at scale, but what if the LEDs
| were mid-mounted into a slot cut into the PCB?
| atticora wrote:
| Or suspended in a wire net.
| alright2565 wrote:
| not at all hard to do, they make "reverse mount" leds, where
| the diode faces into the PCB:
| https://www.digikey.com/en/products/detail/sunled/XZMYK55W-3...
|
| compatible with the exact same pick-and-place machines, you
| just need to drill a hole in the PCB
| pcdoodle wrote:
| That is cool.
|
| The code is lean too, seems like one could learn a lot by trying
| to do this themselves.
| dsalzman wrote:
| Nice example of persistence of vision display. You can use large
| stick versions of this to "paint" images by waving them around.
| K0balt wrote:
| It seems like this might Work even better with a two sided OLED
| screen (2 screens back to back) rather than led array, for better
| resolution? I think that are sufficiently wide angle, at least
| the monochrome ones.
| sporeray wrote:
| I think OLEDs might have a refresh rate issue. The nice thing
| about LEDs is that you can drive them at a very high refresh
| rate.
| buildbot wrote:
| Don't oled displays support pretty high refresh rates? And
| also have way lower GtG latency?
| throwawayben wrote:
| with this kind of spinning display you'd need to multiply
| the frame rate you want by the angular resolution you want.
| So if you're happy with only 20 different angular views and
| only a 20fps refresh rate of the 3d display then that's
| 400fps required of the flat display
| FredPret wrote:
| The rest of the site is filled with dozens of similar very cool
| projects
| francisduvivier wrote:
| Pretty cool, but the bigger the display, the more that refresh
| rate becomes an issue. Say you can refresh the outer pixels on
| the horizonal axis at 100 fps. Then if you want to have 50 pixels
| on the outer half circle, then you can change them at 2fps.
| kragen wrote:
| conventional leds can be driven at several megahertz pretty
| easily. the white type uses a yellow phosphor that fades slowly
| but they can still do kilohertz
| falker wrote:
| The RP2040 tiny is a Nintendo Switch modchip in disguise (47 ohm
| resistors on 3 specific pins).
| bobsmooth wrote:
| Using blender to generate the frames is really clever.
| 55555 wrote:
| This would look better with the LEDs on a transparent PCB, right?
| bee_rider wrote:
| I bet you could to it with those little fiber-optic wires. Not
| the fancy telecommunications ones, the cheap stuff they use to
| make decorations.
|
| I wonder how they respond to being dunked in epoxy.
| blincoln wrote:
| LEDs connected directly by rigid wires (no PCB at all), then
| encased in resin might be worth considering too.
| tasty_freeze wrote:
| holy hell is this guy productive. it is worth scrolling through
| the various one-off projects he has completed and documented:
|
| https://mitxela.com/projects
| fallat wrote:
| I thought so too but look at the dates and the scope of the
| projects. They're just good at managing their time :) I
| probably have just as many projects accumulated over the years.
| DesiLurker wrote:
| .
| davidw wrote:
| I feel like a bit of an incompetent after looking through all
| that.
| jacquesm wrote:
| Just a catalogue of all the skills on display is already the
| stuff of a couple of lifetimes.
| lordwiz wrote:
| Looks Pretty cool, Interesting how blender was integrated into
| such workflows for animation in hardware
| namuol wrote:
| (Great YouTube channel if you're into this sort of thing!)
|
| I wonder if a cheap oled display could be updated fast enough to
| achieve a much higher resolution. It might work but could look
| worse since the space between radial slices would be much larger
| than the pitch of the pixels, most likely.
| skibz wrote:
| I love projects like this that exploit the POV phenomenon.
|
| Here's another cool one I found a while ago:
| https://www.youtube.com/watch?v=wM_Byrv9iBI
| Solvency wrote:
| Ok I just went down the rabbit hole of this guys projects over
| the last decade and I am now thoroughly impressed and utterly
| depressed that I'll never have as much free time as he does.
| djmips wrote:
| Free time is an excuse for most people - I'm not calling you
| out because I don't know you but most people spend a lot of
| time on YouTube - Hn - Watching TV etc and they could be
| working on a cool project instead.
| Solvency wrote:
| Watching TV? YouTube? Sounds like your peer group is biasing
| you. How about struggling to work from home for 8 hours a day
| with two kids with zero familial support, an endless array of
| bills, and every possible life obstacle coming your way 24/7?
| djmips wrote:
| I wasn't calling you out. I don't know you. (look what I
| wrote) - best of luck in your situation!
| garaetjjte wrote:
| He even has entry on this topic: https://mitxela.com/rants
| (scroll down to "Spare Time and Hard Work")
| julianpye wrote:
| His work is even more inspirational after reading this
| rant, as he describes the therapeutic aspect of his
| projects and his base emotions. Still, I can't help but
| excuse my inferior output by admiring his incredible fine
| motor skills and pre-existing expertise in electronics.
| jacquesm wrote:
| Those fine motor skills will go though, use them while
| you have them! Especially for fine soldering work you
| need a very steady hand and that which used to be trivial
| suddenly is a real challenge.
| julianpye wrote:
| Indeed! His soldering work is of the highest art.
| blincoln wrote:
| This is a neat project. With such a low resolution, am I wrong in
| thinking that the flame simulation could be done in real time on-
| chip using a cellular automata algorithm? It would still be nice
| to support pre-rendered video for other purposes, of course.
| merelysounds wrote:
| I'd prefer this kind of spatial computing, I like it more than
| AR/VR - especially that this relies more on human sensory input,
| as opposed to working against it. E.g. no need to simulate head
| tracking.
| brilee wrote:
| geohot built one of these in high school
|
| https://www.forbes.com/forbes/2007/0723/060.html?sh=3c183bcb...
| IAmGraydon wrote:
| This is so awesome.
| sowbug wrote:
| A couple ideas for improvement. If you have extra identical
| motors and disassemble two, you can fashion a rotating power
| transmission system from the brushes in two assemblies. You
| sacrifice two motors for each unit, but it's a perfect fit and
| very reliable (with a cap and rectifier), and you don't have to
| worry about batteries anymore.
|
| The rectifier also provides a signal that the assembly has
| completed a rotation, so you can maintain image stability based
| on actual position, rather than guessing how long a cycle is.
|
| Transmitting power via induction might work, but I was never able
| to deliver it efficiently enough, so to make it work I had to
| turn up the source voltage so high that I worried about fires.
|
| This advice comes from my 2001 Burning Man art project. A very
| sad early prototype is pictured here:
| https://github.com/sowbug/tqw/blob/master/photos/side.jpg. The
| final installation worked great.
| elcritch wrote:
| That is a pretty good idea! The brushes will last a long time.
| Luckily now the rise of wireless phone charging means you can
| get kits like [1] or [2].
|
| It makes me wonder how different LIDAR vendors manage it.
|
| 1: https://www.adafruit.com/product/1407 2:
| https://www.adafruit.com/product/2162
| d_tr wrote:
| Another recently posted cool volumetric display project which did
| not receive much attention:
|
| https://news.ycombinator.com/item?id=38406824
| intrasight wrote:
| No video? Or did I miss it?
| isuckatcoding wrote:
| This makes me wonder if anyone has tried to create the Las Vegas
| sphere on a smaller scale themselves because that would be
| awesome
| iamflimflam1 wrote:
| This is very similar to how hologram fans work - all the
| electronics is in the spinning part. With the fans they often use
| wireless power transfer to drive the top board.
|
| https://youtu.be/bT716nyK0AY
| derac wrote:
| That's so cool! It would be interesting to see how it would
| perform in a vacuum. I wonder how big you could feasibly make it
| with vacuum containment.
| jacquesm wrote:
| Size is mostly about balance and engineering, if you cast the
| whole thing in resin you can spin it as fast as you want (or
| until the resin breaks apart).
| jacquesm wrote:
| This is a really neat little project. Make sure to check out the
| other ones, some of which have been featured on HN before:
|
| https://mitxela.com/projects/hardware
|
| Personal favorite: the MIDI slide whistle.
| ge96 wrote:
| oh yeah, I forgot about the HDMI to OLED display that was crazy
| LAC-Tech wrote:
| That's beautiful. Nothing intelligent to add, just a very neat,
| clever and aesthetic project.
| papichulo4 wrote:
| Ha, came here with similar feelings. Put it on a stick! Is what
| I thought... Could it be on a handle of sorts?
| sigil wrote:
| Many years ago, someone did a similar holographic hack with a
| spinning hard drive motor, a piece of reflective plexiglass
| mounted upright on it, and a small projector. As the plexiglass
| carved out a cylinder, the projector sent a series of frames
| adjusted for each little slice of 3D space. [0]
|
| This gave me a wild idea: what if you could encode a low-
| resolution 3D video on the left channel of a stereo vinyl groove?
| [1] A special record player with a spinning plexiglass plate
| could then play holographic albums. The hologram would stay
| perfectly in sync with the music if you changed speeds or did
| turntable scratching.
|
| [0] If anyone can find a link to the original spinning hard drive
| hologram project please drop it!
|
| [1] I assume this wild idea isn't feasible given vinyl data
| rates?
| gs17 wrote:
| There's a low tech version of the vinyl hologram:
| https://youtu.be/aEbAaL7fPl4
| sigil wrote:
| Different but pretty cool idea!
| Someone wrote:
| > assume this wild idea isn't feasible given vinyl data rates?
|
| Data rates go up if you spin the disk faster, and can get fast
| enough for 2D video. I don't think it was vinyl, but
| https://en.wikipedia.org/wiki/Television_Electronic_Disc:
|
| _"Program information was stored in the form of ridges in the
| surface of a thin, flexible foil disc, which was claimed to be
| sufficiently robust to withstand being played 1,000 times. The
| main technological breakthrough was the vertical recording
| method that reduced the track pitch to 0.007 mm, and increased
| the rotation speed to 1,500 rpm, making it possible to record
| 130-150 grooves per millimeter, compared with the typical 10-13
| grooves on an audio disc. This increased the available
| bandwidth from around 15 kHz to 3 MHz."_
| sigil wrote:
| Amazing, first I've heard of this. Here's footage of someone
| playing a Television Electronic Disc:
| https://youtu.be/XkP4ZJnMVOs?si=QbT4EXrE1dpq-Rtz
| fortran77 wrote:
| There's no "Left Channel" on a stereo vinyl groove. There's an
| A+B channel (horizontal) and A-B Channel (vertical). Left and
| Right are created electronically from these two signals.
| sigil wrote:
| Right, I forgot this detail. Thanks for the correction.
| blkhawk wrote:
| anybody know if it would have been better to put half the LEDs on
| each side of the PCB in alternating lines?
| MrsPeaches wrote:
| For anyone based in or visiting London, exhibitions at 180
| Studios [1] often use this kind of tech for art shows. Well worth
| checking out if you are into art and tech.
|
| [1] https://www.180studios.com/
| joelegner wrote:
| Even if you never intend to attempt a project like this, there is
| something valuable to be gained by reading narratives like this:
| humility. Not many folks could pull this off. I sure could not.
| It's a good reality check.
| orbital-decay wrote:
| Make an acrylic cube or a sphere, put inside a projection surface
| that's able to rotate around one axis. Pump the air out for it to
| be silent and to be able to use a really thin sheet. Spin it with
| an external magnetic field. Project the distortion-corrected and
| spin-synchronized image to it with 2-3 projectors under different
| angles. Bang, you have your own Star Wars display that's entirely
| doable by a hobbyist.
| late2part wrote:
| Cool! Can you do this and write up the steps like the article?
| bigbonch wrote:
| Reminds me of this 20Q toy I had as a kid:
| https://youtu.be/2C1No7cv84o?si=xAFibiv9LeVxM-rF
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(page generated 2023-12-02 23:00 UTC)