7 ms·

Make a Pseudoscope (2005)

89 points by mattbierner 8y ago

mattbierner 8y ago
> A pseudoscope is an optical instrument made with two prisms. As seen in the drawing, the mirrors reverse the image in each eye causing some items viewed through it to look quite unusual: convex objects become concave, things pointing towards you may look like they are pointing away and vice versa. — https://pseudoscope.blogspot.com/2005/06/pseudoscope-is-optical-instrument-made.html https://pseudoscope.blogspot.com/2005/06/pseudoscope-is-opti...
- throwwit 8y ago
  Might be popular with flat-earthers ;-) ... the psychological phenomenon might even be related
- mannykannot 8y ago
  If I am not mistaken, this homemade pseudoscope works on a slightly different principle - it switches the perspective from which each eye sees the object, without any left-right reversal. The two-prism device appears to preserve the perspective of each eye but does a left-right reversal of the images on each retina (I confirmed the non- left-right reversal in the mirror case with a pair of hand-held mirrors.) https://en.wikipedia.org/wiki/Pseudoscope#/media/File:Pseudoscope_prism.png https://en.wikipedia.org/wiki/Pseudoscope#/media/File:Pseudo...
baddox 8y ago
I achieved a presumably similar effect several years ago by viewing my 3D TV (remember those?) with the 3D glasses on upside down. It is definitely very strange having “near” and “far” effectively reversed, yet with all the other depth cues in place.
- m_st 8y ago
  Great idea, I ought to try that too! Now where did I stow away these glasses... and where do I find a 3D movie... :-)
- taneq 8y ago
  A more comfortable way to achieve this is just set the 3D mode to the wrong setting (eg. R|L side-by-side instead of L|R, or under/over instead of over/under). Agreed that it's a really weird feeling, almost like having something brushing your face. (Also, it makes me sad that 3D is no longer a feature of new TVs. I guess I'm just going to have to hold onto the one we've got - I like watching 3D movies even if no-one else in the house does!)
- anonymfus 8y ago
  Basically rich people version of cross-eyed viewing of the stereogram which was set up for diverged viewing.
TuringTest 8y ago
This illusion should be relatively easy to implement as a scene in VR.
dandare 8y ago
I was always wondering, why don't we have periscope windows? What I imagine is a "light intake" on a roof, from which the light is concentrated into a straight long NARROW tube that takes it to an underground flat where the light is dispersed into a fake window. Is such design not possible mathematically or just very expensive? Maybe it could use Fresnel lenses to save on cost and weight. That way we would not get a clear picture of the outside world but at least lot of natural daylight.
- jw1224 8y ago
  I live in a 3-storey apartment building, and one of my neighbours downstairs actually has this. It's actually a bit of a sneaky marketing "hack" by the architects. When the building was being designed a couple of years ago, they put a light tunnel in place running down the vertical length of one side of the building. This took light from the penthouse's roof and channeled it down to the ground floor. By doing this, the architects could turn a 2-bedroom apartment into a 3-bedroom one. By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in. As my neighbour's apartment was surrounded on two sides by adjoining walls, this meant a room mid-way through the length of the building (and otherwise devoid of natural light) could be considered a bedroom, and marketed as such.
  - Spare_account 8y ago
    > It's actually a bit of a sneaky marketing "hack" by the architects. > By doing this, the architects could turn a 2-bedroom apartment into a 3-bedroom one. By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in. This doesn't sound right to me, so I checked and the best I can come up with is this, from the building regulations: https://www.planningportal.co.uk/info/200130/common_projects/5/basements/2 https://www.planningportal.co.uk/info/200130/common_projects... There is reference to fire escape/egress and to ventilation but nothing about natural light. I don't think there is any requirement to have natural light for a room to be defined as a bedroom. The subject of what a bedroom actually is appears to be somewhat murky. The Building Regulations use terms like "habitable space" for most rooms within a house which I assume allows for the fact that one persons front room/lounge/living room might be another persons ground floor bedroom/granny annex/lodger's bedsit. There are some specific cases such as kitchens and bathrooms that don't tend to be as ambiguous, but I don't think there is a regulation that backs up your statement "By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in." http://www.rics.org/uk/knowledge/glossary/what-is-a-bedroom/ http://www.rics.org/uk/knowledge/glossary/what-is-a-bedroom/
app4soft 8y ago
Title should be: Make a Pseudoscope (2005)
- vermilingua 8y ago
  I mean, does knowing it was written in 2005 change how you read it? Titles only really need years if the context is important, and AFAIK the physics of prisms haven't changed all that much in 13 years.
  - tomhoward 8y ago
    It also helps readers to know if they've read the article before.
Tepix 8y ago
Has someone built a virtual pseudoscope for virtual reality goggles such as Oculus Go?
scentoni 8y ago
What's the name of an optical device like this that merely magnifies the stereo separation without crossing the images? I see examples of photographs taken this way but not real-time viewing instruments https://en.wikipedia.org/wiki/Stereo_photography_techniques#Longer_base_line_for_distant_objects_–_"Hyper_Stereo" https://en.wikipedia.org/wiki/Stereo_photography_techniques#...
- jloughry 8y ago
  Look at old battleship rangefinders. Some of them had 8 or 9 metre baselines. See https://en.wikipedia.org/wiki/Coincidence_rangefinder#Stereoscopic_rangefinders https://en.wikipedia.org/wiki/Coincidence_rangefinder#Stereo...

89 points by mattbierner 8y ago

> A pseudoscope is an optical instrument made with two prisms. As seen in the drawing, the mirrors reverse the image in each eye causing some items viewed through it to look quite unusual: convex objects become concave, things pointing towards you may look like they are pointing away and vice versa. — https://pseudoscope.blogspot.com/2005/06/pseudoscope-is-optical-instrument-made.html https://pseudoscope.blogspot.com/2005/06/pseudoscope-is-opti...

throwwit 8y ago
Might be popular with flat-earthers ;-) ... the psychological phenomenon might even be related
mannykannot 8y ago
If I am not mistaken, this homemade pseudoscope works on a slightly different principle - it switches the perspective from which each eye sees the object, without any left-right reversal. The two-prism device appears to preserve the perspective of each eye but does a left-right reversal of the images on each retina (I confirmed the non- left-right reversal in the mirror case with a pair of hand-held mirrors.) https://en.wikipedia.org/wiki/Pseudoscope#/media/File:Pseudoscope_prism.png https://en.wikipedia.org/wiki/Pseudoscope#/media/File:Pseudo...

baddox 8y ago

I achieved a presumably similar effect several years ago by viewing my 3D TV (remember those?) with the 3D glasses on upside down. It is definitely very strange having “near” and “far” effectively reversed, yet with all the other depth cues in place.

m_st 8y ago
Great idea, I ought to try that too! Now where did I stow away these glasses... and where do I find a 3D movie... :-)
taneq 8y ago
A more comfortable way to achieve this is just set the 3D mode to the wrong setting (eg. R|L side-by-side instead of L|R, or under/over instead of over/under). Agreed that it's a really weird feeling, almost like having something brushing your face. (Also, it makes me sad that 3D is no longer a feature of new TVs. I guess I'm just going to have to hold onto the one we've got - I like watching 3D movies even if no-one else in the house does!)
anonymfus 8y ago
Basically rich people version of cross-eyed viewing of the stereogram which was set up for diverged viewing.

TuringTest 8y ago

This illusion should be relatively easy to implement as a scene in VR.

dandare 8y ago

I was always wondering, why don't we have periscope windows? What I imagine is a "light intake" on a roof, from which the light is concentrated into a straight long NARROW tube that takes it to an underground flat where the light is dispersed into a fake window. Is such design not possible mathematically or just very expensive? Maybe it could use Fresnel lenses to save on cost and weight. That way we would not get a clear picture of the outside world but at least lot of natural daylight.

jw1224 8y ago
I live in a 3-storey apartment building, and one of my neighbours downstairs actually has this. It's actually a bit of a sneaky marketing "hack" by the architects. When the building was being designed a couple of years ago, they put a light tunnel in place running down the vertical length of one side of the building. This took light from the penthouse's roof and channeled it down to the ground floor. By doing this, the architects could turn a 2-bedroom apartment into a 3-bedroom one. By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in. As my neighbour's apartment was surrounded on two sides by adjoining walls, this meant a room mid-way through the length of the building (and otherwise devoid of natural light) could be considered a bedroom, and marketed as such.
- Spare_account 8y ago
  > It's actually a bit of a sneaky marketing "hack" by the architects. > By doing this, the architects could turn a 2-bedroom apartment into a 3-bedroom one. By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in. This doesn't sound right to me, so I checked and the best I can come up with is this, from the building regulations: https://www.planningportal.co.uk/info/200130/common_projects/5/basements/2 https://www.planningportal.co.uk/info/200130/common_projects... There is reference to fire escape/egress and to ventilation but nothing about natural light. I don't think there is any requirement to have natural light for a room to be defined as a bedroom. The subject of what a bedroom actually is appears to be somewhat murky. The Building Regulations use terms like "habitable space" for most rooms within a house which I assume allows for the fact that one persons front room/lounge/living room might be another persons ground floor bedroom/granny annex/lodger's bedsit. There are some specific cases such as kitchens and bathrooms that don't tend to be as ambiguous, but I don't think there is a regulation that backs up your statement "By law (at least in the UK), you cannot market a room as a bedroom unless it has natural light coming in." http://www.rics.org/uk/knowledge/glossary/what-is-a-bedroom/ http://www.rics.org/uk/knowledge/glossary/what-is-a-bedroom/

app4soft 8y ago

Title should be: Make a Pseudoscope (2005)

vermilingua 8y ago
I mean, does knowing it was written in 2005 change how you read it? Titles only really need years if the context is important, and AFAIK the physics of prisms haven't changed all that much in 13 years.
- tomhoward 8y ago
  It also helps readers to know if they've read the article before.

Tepix 8y ago

Has someone built a virtual pseudoscope for virtual reality goggles such as Oculus Go?

scentoni 8y ago

What's the name of an optical device like this that merely magnifies the stereo separation without crossing the images? I see examples of photographs taken this way but not real-time viewing instruments https://en.wikipedia.org/wiki/Stereo_photography_techniques#Longer_base_line_for_distant_objects_–_"Hyper_Stereo" https://en.wikipedia.org/wiki/Stereo_photography_techniques#...

jloughry 8y ago
Look at old battleship rangefinders. Some of them had 8 or 9 metre baselines. See https://en.wikipedia.org/wiki/Coincidence_rangefinder#Stereoscopic_rangefinders https://en.wikipedia.org/wiki/Coincidence_rangefinder#Stereo...