[HN Gopher] Civil War in 3D: Stereographs from the New-York Hist...
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Civil War in 3D: Stereographs from the New-York Historical Society
(2015)
Author : LorenDB
Score : 43 points
Date : 2025-05-29 15:43 UTC (7 hours ago)
(HTM) web link (www.nyhistory.org)
(TXT) w3m dump (www.nyhistory.org)
| ramesh31 wrote:
| You can see the effect in these images directly without a device,
| by simply crossing your eyes and focusing on the third central
| image that appears, similar to those 3D optical illusion books:
| https://youtu.be/zBa-bCxsZDk
| JKCalhoun wrote:
| The cross-eyed method requires the images be swapped left-for-
| right.
| kazinator wrote:
| Not sure why you are downvoted; that is correct.
| kazinator wrote:
| This gallery presents the original stereograms in their stare-
| into-distance configuration (left image goes with left eye,
| right with right), not cross-eyes configuration (left image
| goes with right eye and vice versa).
| JeremyHerrman wrote:
| Is it just me or are some of these examples not actually stereo
| image pairs?
|
| I'm just crossing my eyes to see the "negative" depth image but
| some like "McLean's House" and "Lincoln visits General McClellan
| at Antietam" don't appear to have any depth changes between them.
| JKCalhoun wrote:
| You need to swap left and right images to use the cross-eyed
| method on these. You can try downloading as an image, use an
| app like Preview to Flip Horizontal (that will work).
|
| Otherwise you're seeing a kind of inverse stereo image.
|
| (EDIT: Having said that, I tried a few of the images and the
| stereo effect is subtle. The soldier on the horse -- I was not
| even able to get that to "snap" for me. I am not great with
| cross-eyed stereo though.)
| JeremyHerrman wrote:
| yes understood that cross-eyed method inverts the depth. My
| point was that some of the image pairs are from the exact
| same perspective - so there is no stereo depth no matter if
| you're using cow-eyed or cross-eyed.
| JKCalhoun wrote:
| Yeah, if there is depth, it was pretty subtle on the few I
| got to work.
| kazinator wrote:
| These images were prepared for insertion into a stereogram in
| which the left eye looks at the left image and right eye looks
| at the right image, through a magnifying lens. When viewing
| with the naked eye, you must stare past the images into the
| distance to get them to converge that way.
| JeremyHerrman wrote:
| Thanks, I understand how stereograms work and have quite a
| few of these IRL. I use cross-eyed method to quickly view
| them (albeit inverted depth) when shown on screen.
|
| I've tried to show my point in these videos which show
| basically no difference between the two images when
| overlapped and crossfaded between the two.
| https://imgur.com/a/RMy3QA3
| kazinator wrote:
| I agree that particular image is a dud; I was not able to
| perceive any depth.
|
| The creator mistakenly used the same image twice.
|
| The two men in a tent image is likewise a dud. If we look
| at the pole at the tent entrance, there is no difference in
| parallax between that and objects at the back wall.
|
| The Abe Lincoln doesn't pop out much for me.
|
| The dead soldiers in the field also seems to be identical
| images.
|
| The clearly genuine ones are the horse-drawn carriage in
| the forest, and the horseman in front of the cannon.
| JeremyHerrman wrote:
| Here are some videos trying to show what I mean. I overlapped
| the two images on top and crossfaded between the two. Aside
| from some minor distortion I don't see any major differences
| normally found between stereo pairs.
|
| https://imgur.com/a/RMy3QA3
| saddat wrote:
| Create two pictures from it and use
| https://huggingface.co/spaces/cavargas10/TRELLIS-Multiple3D
| kazinator wrote:
| For casual viewing with the unaided eye, you want to present
| stereograms in cross-your-eyes order not stare-into-distance
| order.
|
| Most people are not able to cause their eyes to diverge, so the
| scale of images in a stare-into-distance stereogram is limited by
| the interocular distance.
|
| In cross-eye configuration, larger images can be used.
|
| (Of course, the use of magnification in stereoscopes relieves the
| issue, as well as making it easier for the eyes to focus, since
| the magnified virtual images appear farther away. Viewing stare-
| into-distance stereograms requires the eyes to believe they are
| looking far away due to the parallel gaze, while simultaneously
| focusing near on the images; magnification brings the images
| farther out.)
| LorenDB wrote:
| I personally find the crosseyed type to be nearly impossible,
| while the parallel type are pretty easy for me. So I think it
| really depends on the person. Additionally, most stereograms
| I've seen (e.g. coffee-table books) have been parallel type.
| kazinator wrote:
| The parallel types are also very easy for me, but they are
| always small.
|
| If the spacing between them is wider than my inter-ocular
| distance, I find them impossible to converge.
|
| I made stereograms in the past and wanted to see larger
| images with the naked eye, so I had no choice but swap the
| images and cross the eyes.
| ge96 wrote:
| For an example that works see this squirrel sorry reddit link
|
| https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd....
|
| crazy but I feel sick now ha, I had a VR headset before and I'd
| get super sick trying to play FO4, VRChat wasn't bad
| bredren wrote:
| Would be cool to get these converted into spatial photos for
| Vision Pro.
| mdswanson wrote:
| Not too many steps away from this:
| https://blog.mikeswanson.com/spatial/
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(page generated 2025-05-29 23:00 UTC)