[HN Gopher] Cross Views
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Cross Views
Author : moultano
Score : 98 points
Date : 2025-02-26 18:19 UTC (4 hours ago)
(HTM) web link (moultano.wordpress.com)
(TXT) w3m dump (moultano.wordpress.com)
| tombert wrote:
| I love this effect. I had a book of Magic Eye pictures as a kid,
| which was a similar effect.
|
| I'm not sure how practical the "crossing your eyes to get 3D"
| thing actually is, it makes my eyes water after a minute or so,
| but it's still sort of cool to see my cheapy monitor doing 3D
| without any special glasses.
| tomw1808 wrote:
| I had the same book - the one with the black border? :) There
| was a dolphin or something, right? So long ago, can barely
| remember...
|
| The water eye thing only happens to me if I cross my eyes and
| focus before the picture and not behind the picture. The latter
| takes some time to let the eyes relax, but its much more
| natural.
| RIMR wrote:
| If you stitch the photos together seamlessly, you can display
| them on a VR headset in a really natural way. I take stereo
| images in landscape mode, stitch them together top/bottom, and
| then enjoy them on my Quest 2 using the Pigasus media player.
|
| If you use a 180deg fisheye lens, you can immerse yourself in
| the scene. just make sure to keep the camera perfectly level,
| or you'll end up making yourself sick if you try to view the
| images unadjusted.
| voytec wrote:
| "Wow, a sailboat!"
| regularfry wrote:
| I seem to recall that Magic Eye pictures had you decross your
| eyes, so you were looking past the page. It was a bit harder to
| do.
| alnwlsn wrote:
| I only learned somewhat recently that a lot of (or all?) Magic
| Eyes are meant to be parallel viewed instead of cross eyed. The
| difference was pretty impressive the first time I saw one
| correctly.
| nashashmi wrote:
| I want to know why cannot the multiple cameras on my phone be
| used to create 3D images.
| tomw1808 wrote:
| They can, or? Apple calls that spatial videos, or does that
| work differently?
| Philpax wrote:
| Yes, the spatial videos that iPhones can record are just
| stereoscopic video. This hasn't been cloned by other
| manufacturers because there have been very few viewing
| devices that they own, but that might change with Android XR.
| dist-epoch wrote:
| Because they are not the same focal length? Although I'm sure
| software can mitigate that to some extent.
| regularfry wrote:
| They're not far enough apart. Stereo vision on humans is best
| inside 3-5 metres, usually, and by 10 metres out is not that
| great.
|
| That's with pupils 65mm apart, give or take. Now scale that
| down to the horizontal distance between lenses on a phone.
| Coincidentally on mine they are about 13mm apart. You just
| multiply everything down linearly: my camera has the same
| experience at 60mm distance from an object as I do at 3m. It
| would be pretty useless past 2m, but also with those
| constraints you'd notice the quality drop off with range within
| a single object that was approaching 50cm depth.
|
| Now that's OK itself, you could get some useful work done with
| that, but there are so many provisos to it that it would be
| very hard to sell as a feature. To top that off it's
| algorithmically painful. There's a reason the commercial 3D
| scanners don't (typically, only) use stereo pairs; there's
| almost always a better way to do it.
| regularfry wrote:
| (oh, and to get out ahead of questions: Spatial Video capture
| on the iphone 15 apparently uses the LIDAR sensor for the
| depth map, not just the cameras)
| deadbabe wrote:
| I thought this would be about wigglegrams
| Kerbonut wrote:
| Is it just me or do they have some of the left/right images
| swapped?
| throw310822 wrote:
| Came to say the same. Depth is inverted for me. Is it because
| instead of looking at each picture with the eyes straight, we
| cross them (and each sees the opposite picture)?
| moultano wrote:
| If they look inverted you are probably diverging your eyes
| instead of crossing them. In that case the images in this
| section should look correct.
| https://moultano.wordpress.com/2025/02/24/you-should-make-
| cr...
| foobarian wrote:
| Heh I thought you must've tested these on a teeny tiny
| monitor to make them work. No wonder! But of course when
| crossing eyes there is essentially no limit. Thanks for the
| clarification.
| moultano wrote:
| I just went back and doubled checked, and they're all correct.
| If they look inverted, you are probably diverging your eyes
| ("parallel view") instead of crossing them. If that's more
| comfortable for you there is a section of images arranged with
| that orientation at the end of the article.
| dragonwriter wrote:
| The first set are (as the text says) designed for cross-eyed
| viewing, the others for parallel. These use opposite left/right
| arrangement. So if it feels like half of them are backwards,
| you are maybe using the same viewing method for both sets?
| zehaeva wrote:
| Ugh, there's some people out there who cannot see these. Not for
| a lack of trying, I've personally been trying since the 90s.
| wkat4242 wrote:
| It took me a while too. Especially those double images that
| look totally contorted and only come out when you relax your
| focus. It took ages but suddenly they popped and now i can do
| them every time. Once they came through they were crystal
| clear.
| kookster310 wrote:
| The trick for me was to completely cross my eyes and produce
| the double images, then slowly uncross/cross them until I could
| start to see the image, which eventually clears up.
| stewarts wrote:
| I am with you. I could also never see the hidden image things.
| Been trying for 40 years.
| dist-epoch wrote:
| Do you manage to align the two small white squares above each
| picture so they are on top of each other?
| moultano wrote:
| Yes.
| tantalor wrote:
| There are two communities, you need to find out which one you
| belong to.
|
| https://www.reddit.com/r/CrossView
|
| https://www.reddit.com/r/ParallelView
|
| There is a test image you can try:
|
| https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fg...
|
| Whichever "view" looks to be closer is the one you should use.
| StevenNunez wrote:
| I don't think I understand what the image is supposed to do.
| I can only see from one eye at a time.
| alistairSH wrote:
| I don't get it... the reddit image is the same on both sides.
| Trying to look at it cross-eyed just gives me a headache.
|
| "Foreground text describes viewing type" - there is no
| foreground, it's just text on a page?
| AndrewStephens wrote:
| I have always had trouble with magic-eye pictures - I am told
| my eyes are quite different shapes. I can see stereograms with
| some effort.
|
| I believe that there is a small percentage of the population
| for whom stereoscopic images (including 3d films) just don't
| work at all. Either they lack the ability to perceive depth
| directly or their brains aren't fooled by images with no
| parallax relative to their eye movements. I don't have any
| cites for this though.
| cromulent wrote:
| Amblyopia and monocular diplopia here. No way I can see these,
| my brain won't let me.
| smusamashah wrote:
| Have you tried using pipes/kitchen towel rolls?
|
| As in, try doing something like this:
|
| 1. Zoom the images small enough to be almost parallel to your
| eyes.
|
| 2. Make a binocular out of used kitchen rolls.
|
| 3. Each side should look at exactly one of the images
|
| It should just work. Both images should converge like they do
| in a binocular.
|
| (you can then try removing this DIY binocular suddenly and see
| if you can maintain focus)
| nightpool wrote:
| Presumably that would only work for the wall-eyed (diverging)
| images given at the bottom of the screen, the cross-eyed
| (converging) images given throughout most of the article
| wouldn't work with this technique.
| EvanAnderson wrote:
| I've done this with my SLR. Moving the camera different amounts
| can give a more pronounced effect, however it can be more
| difficult to get the image to converge.
|
| I had a lot of fun with doing this 20 years ago. Sadly, my visual
| acuity has become significantly different between my eyes (even
| w/ correction) and the enjoyment of 3D displays has really
| diminished as as result.
|
| Just musing because I'm working and busy:
|
| I wonder how difficult it would be to do video. (Obviously you'd
| have to shoot two videos in parallel versus just moving the
| camera and shooting again.)
|
| Converting existing 3D videos to a cross-eyed viewing format
| would probably be the easiest way to experiment with it. I wonder
| if anybody has done that. I've never looked at 3D movie formats
| before. I always assumed it was two interleaved streams.
| wkat4242 wrote:
| You should move it by the distance of your pupils for the best
| effect. Mine is bog standard 63mm so I'm lucky.
|
| If you get it wrong things will look too big or too small and
| the 3D effect will be softer or too pronounced.
| llm_trw wrote:
| The point is that you can force the respective of a giant or
| an ant if you so choose.
|
| Using two cameras I had a time lapse of a fog coming in where
| you could see the 3d structure becuase they were at two
| different streets looking out.
|
| Like op this was done nearly 20 years ago. Now you don't even
| get fog any more.
| Jarmsy wrote:
| I remember reading about a physical device someone
| constructed with mirrors (I think at an early burning man)
| that gave you the experience of a huge inter ocular
| distance to get a giant's eye view. I've always wanted to
| try one (or the opposite to experience a tiny inter ocular
| distance).
| Jarmsy wrote:
| Found it http://eyestilts.com/intro.html
| regularfry wrote:
| A pair of periscopes laid flat will do it, but it'll
| really confuse your eyes. I can feel it on these images:
| the eye muscles are trying to converge on a distance
| closer than the focusing muscles want to focus on, and I
| can tell that's a bit weird. That might be an age thing
| though.
| regularfry wrote:
| The reason you need to change the inter-frame distance is
| because the amount of information carried by the parallax
| drops off quite quickly, to the extent that at the sort of
| distance in the tree photo, your brain is mostly using
| motion cues for 3d reconstruction, not stereo vision.
| Increasing the horizontal distance simulates bringing
| everything correspondingly closer.
| alnwlsn wrote:
| I remember seeing video done this way on youtube during the 3D
| tv craze about 10 years ago (not the 3d stuff that youtube
| supported, this was just people messing about with 2 images
| side by side). It worked about as well as the examples here,
| but was not a particularly comfortable experience for anything
| longer than a few minutes.
| alnwlsn wrote:
| For that matter, there are a couple of "Magic Eye" videos out
| there, which look like TV static until you cross your eyes
| enough.
| mncharity wrote:
| > I wonder how difficult it would be to do video
|
| One approach is time-shifted side-window video. Time-offset
| frame pairs from mono video that's pointed perpendicular to
| camera motion. Pretending that frames offset in space, time,
| and orientation, are offset only in horizontal-space-
| perpendicular-to-shot. Sufficiently perpendicular that
| difference in apparent size within pairs doesn't bite, and
| similarly for motion stability, orientation, distance from
| subjects, and non-horizontal motion. Phone video out the side
| window of a train/plane/bus/car with a view, or a drone footage
| segment that meets constraints. River seen from bridge-crossing
| train window; waiting rocket seen from circling drone. Upside
| is easy capture. Downsides include: non-static things don't
| fuse (traffic by river, fog off rocket); it can be a pain to
| find usable segments in existing video.
| Karawebnetwork wrote:
| When they wrote "your screen can display 3D photos", I thought it
| would be a hardware hack and not something that depends on a
| human physiology hack.
|
| Something like stereoscopic GIFs come to mind, e.g.
| https://tenor.com/fr-CA/view/dain-stereoscopic-daingifs-3d-m...
|
| In other words, taking the two images and swapping them quickly
| creates the illusion of depth.
|
| Edit:
|
| Looking into it, there's a word for it. Wiggle stereoscopy:
| https://en.wikipedia.org/wiki/Wiggle_stereoscopy
| zro wrote:
| There's a whole bunch of these over at
| https://old.reddit.com/r/wigglegrams/ if you want more
| stronglikedan wrote:
| > Your screen can display 3D photos.
|
| That's a stretch, but I guess clickbait is required to get
| engagement nowadays.
| moultano wrote:
| As long as you don't regret the click, I don't regret baiting
| the click. :)
| ellenhp wrote:
| > nowadays
|
| People have been writing provocative titles for things since
| before the internet.
| thih9 wrote:
| I prefer wigglegrams. If you're looking for an example -
| Wikipedia page has one from 1927[1]!
|
| [1]: https://en.wikipedia.org/wiki/Wiggle_stereoscopy
| blululu wrote:
| Was going to say the same thing. Presenting stereo pairs has a
| lot of layout and resolution issues to say nothing of the fact
| that some people have stereo blindness to varying degrees (lazy
| eye is an extreme case). The author is correct that stereo
| depth can greatly enhance an image, but a wigglegram does this
| at full resolution with no visual puzzle solving.
| haunter wrote:
| Nintendo 3DS gang rise up! Though it wasn't perfect or useful
| that much it was still a nice feature, made some fun photos with
| it.
| ben7799 wrote:
| I can generally see the Magic Eye pictures very well.. these are
| way harder.
|
| The tiny thumbnails at the bottom of the page work, but the
| larger images I can't cross my eyes enough.
|
| I think it depends greatly on getting the screen/image size just
| the right size and also getting the viewing distance right. On
| large monitors it seems harder to see.
| moultano wrote:
| Yes, making them smaller certainly helps.
| Agree2468 wrote:
| > You can do this by holding your finger substantially in front
| of the image, and focusing solely on the finger with your eyes,
| while turning your mind's attention to the image behind it
| while keeping your eyes still.
|
| This tip in the article helped me a lot, it's much easier to
| cross your eyes further with something to actually focus on
| ortusdux wrote:
| It's helpful if you can smoothly zoom in on the images. Start
| zoomed out far enough that you can easily see the effect, and
| then slowly enlarge the images. Your brain will work to keep
| them in focus.
| on_the_train wrote:
| I believe the author switched left and right. Because the
| inverse ones at the bottom work fine
| moultano wrote:
| Magic eye pictures are viewed by diverging your eyes, so the
| "parallel view" versions at the bottom work correctly with
| that method.
|
| "Cross view" pictures require converging your eyes, so the
| images have to be in the opposite position from what your eye
| would see.
| ben7799 wrote:
| You're right.. guess I always thought Magic Eye was
| converged.
|
| Once I look at the ones at the bottom and just zoom in/out
| in the browser I can see them perfectly.
|
| I have a 33" monitor and seeing them means sitting much
| closer than normal and then zooming out in the browser.
| spookie wrote:
| The best way I came across doing this is to try and do a
| "thousand yard stare" while looking at the image. It's super
| reliable.
| colingauvin wrote:
| This is very common in structural biology papers, where you need
| to make figure of complex 3D arrangements of atoms, but the
| figures must be printed in 2D. Typically using molecular modeling
| software, you find your view of choice. Then you rotate +- 0.5deg
| and render two images, and put those side by side as a stereo
| pair figure.
|
| It takes quite a bit of practice to see them well:
|
| https://spdbv.unil.ch/TheMolecularLevel/0Help/StereoView.htm...
| regularfry wrote:
| I did this on a school project back in the 90's, with a
| structure of quinol clathrate that was completely wrong but
| very pretty. I was _very_ into povray at the time. My chemistry
| teacher didn 't quite know what to make of it...
| BrandoElFollito wrote:
| Thanks for that! It is quite impressive and I learned to see
| the 3D molecule on first try.
|
| I remember seeing something similar, but made of an array of
| dots (you did not know what was behind the doors until you see
| it by crossing your eyes)
| throwaway494932 wrote:
| The video game Magic Carpet had a couple of 3D modes, anaglyph 3d
| requiring blue/red classes, and stereogram mode [1]. The latter
| was not really usable, but it was a cool trick, expecially for
| the time ('94).
|
| [1] https://youtu.be/iZT-S2F191I?si=8k9jniqA98wgq0Hu&t=1090
| StevenNunez wrote:
| Jokes on you! I can only see from one eye at a time!
| fffrantz wrote:
| Yep, same here. Discovered I was stereoblind quite late as well
| as I thought it was the norm and my brain just got used to it.
| rahimnathwani wrote:
| most stereograms are designed to look correct when you cross your
| eyes
|
| This is how I look at stereograms (looking nearer than the page),
| but at least some of the images on this page seem like they're
| designed for the other way around (looking in the distance,
| beyond the page).
|
| This one looks weird when I look at it cross eyed, but fine when
| I look at the other way.
|
| https://moultano.wordpress.com/wp-content/uploads/2025/02/17...
| moultano wrote:
| Yes, the ones at the bottom, in the "Parallel View" section are
| designed to be viewed the other way.
| rahimnathwani wrote:
| Sorry, I stopped reading part way and was just viewing the
| cool images! That will teach me!
|
| I was confused that some were fine and others (the later
| ones) looked weird!
| fritzo wrote:
| A great source for stereo pairs is NOAA's aerial imagery data,
| consisting of various snapshots along an airplane's trajectory.
| For example here is a stereo pair of Desecheo Island:
|
| https://cdn.coastalscience.noaa.gov/datasets/aerialphotodb/u...
|
| https://cdn.coastalscience.noaa.gov/datasets/aerialphotodb/u...
|
| EDIT it can be tedious to discover such pairs. If only there were
| a tool...
| LVB wrote:
| I've been able to view these type of pictures forever. But I'll
| credit the article with today being the first time I've actually
| taken them myself, put them side by side in my notes app, and
| been pretty impressed with how simple it was to get a neat
| effect.
| moultano wrote:
| Great! I wrote this in the hopes that more people would start
| making them, because I love them.
| smusamashah wrote:
| Those who fail to cross eye/parallel eye these images can try
| looking at these through a (DIY) binocular (empty pipes/used
| kitchen roll should work the same).
|
| It will only work with parallel eye images though (at the end of
| this article).
| CGamesPlay wrote:
| Since the advent of models like Depth Anything, you can now
| convert 2D images into this effect using them plus a bit of
| creative processing. Here's a non-technical overview that plugs
| some software and talks about the underlying models:
| https://www.owl3d.com/blog/2d-to-stereoscopic-3d-with-ai-dep...
|
| Bonus, I also found this real-time 3D-ifier for your screen:
| https://github.com/zjkhurry/stereopsis-anything
| whycome wrote:
| I'm surprised that phone manufacturers don't stick cameras on
| opposite ends of the phone to allow the quick capture of these.
| JKCalhoun wrote:
| To simplify capture, I've picked up a couple of digital stereo
| cameras (Fujifilm FinePix REAL 3D is a good one). The image
| quality is so-so and they're fairly affordable still on eBay
| (maybe $200 or so).
|
| Last summer on a road trip to Alaska, it was almost my exclusive
| camera for the trip. When I got back I wrote an app to take the
| MPO files it contains and turn them into a printable parallel-
| view image. The side-by-side images are intended to be printed
| and used in an old-fashioned stereoscope.
|
| https://github.com/EngineersNeedArt/Stereographer
| jasonjmcghee wrote:
| I had to, hopefully you don't mind moultano!
|
| Same content, but all lined up and rendered the whole article in
| cross-view.
|
| You can now read the article and see the pictures while in cross-
| view.
|
| https://jasonjmcghee.github.io/you-should-make-cross-views-3...
| moultano wrote:
| Clever!
| BrandoElFollito wrote:
| What I find funny is that once you get the fix, you can move your
| eyes around the 3D picture without losing the fix
| Agingcoder wrote:
| I'd love to look at these pictures but have never succeeded. In
| particular, I find crossing my eyes to be a rather painful ( as
| in, it physically hurts ) experience so stop immediately if I
| try.
| jrmg wrote:
| I can _just about_ do it, but it messes up my ability to focus
| normally for ages afterwards. Doesn't feel like it's good for
| my eyes...
| veilrap wrote:
| This is why I never do the cross-eyed version of focusing on
| these. For me that's always been uncofortable.
|
| Using the parallel view, or focusing out beyond the picture to
| make the images converge has always been easier and more
| comfortable for me.
| jjtheblunt wrote:
| january 1983 issue of Creative Computing had an article on stereo
| vision, and I build the stereoscope in it, and wrote basic for my
| IBM PC to do this. Awesome!
|
| https://www.atarimagazines.com/creative/v9n1/162_Stereo_grap...
| perching_aix wrote:
| Often underappreciated detail when it comes to stereoscopic 3D is
| that the image produced is not actually fully 3D still.
|
| Even with just a single eye, it is possible to see depth: this
| would be via monocular depth cues, such as depth of field.
|
| If you ever wondered why 3D visuals, no matter how technically
| advanced, never quite felt right, this is likely the culprit.
| When your eyes adapt to the stereo 3D cues, the monocular cues
| are lost and vice versa. There are some VR technologies that do
| hope to achieve both at the same time using eye (and iris?)
| tracking, but I haven't been following the topic for a while.
| It's essentially a quest for a lightfield display.
| mxfh wrote:
| The monocular depth cues are not lost; rather, the main issue
| with VR and stereoscopic images is the forced depth focus. This
| creates a mismatch between vergence and accommodation, which
| can interfere with natural depth perception. There is extensive
| research on this topic, particularly regarding the vergence-
| accommodation conflict:
|
| https://en.wikipedia.org/wiki/Vergence-accommodation_conflic...
| perching_aix wrote:
| Yes, that's the effect I'm referring to. Maybe my wording was
| too sloppy.
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(page generated 2025-02-26 23:00 UTC)