[visionlist] [cvnet] Trying to demonstrate stereoscopic vision remotely

Sun Mar 22 00:02:13 -04 2020

Excellent point, Bart!  I've known that, but I probably wouldn't have
thought to mention it to students.  Now I will.

Best wishes,

Les

On Sat, Mar 21, 2020 at 10:22 PM Barton Anderson <
barton.anderson at sydney.edu.au> wrote:

> Note on stereo photography:  You should *only* translate the  camera
> horizontally, you should NOT rotate it to keep an  object of interest in
> the center of the image.  Rotation will induce vertical disparities that
> are unfusable.  There’s some good instruction here:
>
>
> https://books.google.com.au/books?id=6CzuydFlMpwC&pg=PA129&lpg=PA129&dq=should+you+rotate+the+camera+when+taking+stereo+photos&source=bl&ots=B0vEcTopGt&sig=ACfU3U08DiG1SGznUn0ImCUfV0jUiOutSg&hl=en&sa=X&ved=2ahUKEwiihImmjq3oAhW0guYKHQ2jDYoQ6AEwEXoECA0QAQ#v=onepage&q=should%20you%20rotate%20the%20camera%20when%20taking%20stereo%20photos&f=false
>
> -Bart Anderson
>
>
>
> *From: *visionlist <visionlist-bounces at visionscience.com> on behalf of
> Lester Loschky <loschky at ksu.edu>
> *Date: *Sunday, 22 March 2020 at 9:11 am
> *To: *David Peterzell <davidpeterzell at me.com>
> *Cc: *David Peterzell <dpeterzell at berkeley.edu>, cvnet <
> cvnet at mail.ewind.com>, Christopher Tyler <cwtyler2020 at gmail.com>, "
> visionlist at visionscience.com" <visionlist at visionscience.com>
> *Subject: *Re: [visionlist] [cvnet] Trying to demonstrate stereoscopic
> vision remotely
>
>
>
> Love it, David!  I've made those on my own as well, but it hadn't
> occurred to me to teach students how to do it.  I think that really will
> make the concepts very concrete for them.  And, as Christopher mentions in
> his Scholarpedia page, crossed eye viewing is easier for most people than
> the "look through" method, so I think a lot of students can get that to
> work.  Wonderful idea!
>
>
>
> Best wishes,
>
>
>
> Les
>
>
>
> On Sat, Mar 21, 2020 at 1:56 AM David Peterzell <davidpeterzell at me.com>
> wrote:
>
> In addition to showing them Christopher Tyler’s Stereogram (using Magic
> Eye examples), I do my best to teach them to free fuse. If that goes well
> with a few of them, then I teach them how to make their own stereo photos
> using the cameras on their smart phones.  1. Have your subject hold still.
>  2. Take a photo.  3. Take a second photo with the camera moved just a
> couple inches to the left or right, still centered on the subject.  4. Put
> the photos in something like PowerPoint. 5. Crop and realign the photos as
> needed (crossed or uncrossed). 6. View  This isn’t for everyone, and some
> people get headaches.  But I’ve had many students have a blast with this
> once they learn this. It has always seemed to me to be a good way to teach
> about stereoscopic vision and the construction of binocular depth
> perception.
>
>
>
> Here are just a few of my own examples, all made on the spot with an
> iPhone.  These sets are made for crossed not uncrossed viewing.  If they
> appear small, click on them to open them.  Who can find the Serbian vision
> scientists?
>
>
>
> Dave
>
>
>
>
>
>
>
> *David Henry Peterzell, Ph.D., Ph.D. --Professor, John F.
> Kennedy University, Clinical Psychology Doctoral Program, College
> of Psychology --Visiting Scholar, University of California, Vision Science
> Program, School of Optometry*
>
>
>
> *JFKU Top Minds video: *
>
> *http://blog.jfku.edu/john-f-kennedy-top-minds-professor-david-peterzell-phd/
> <https://protect-au.mimecast.com/s/IfNFC81V0PTOkqgjInUxz5?domain=blog.jfku.edu/>*
>
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> Click on this one to view.  (crossed and uncrossed)
>
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>
> On Mar 20, 2020, at 9:50 PM, Christopher Tyler via cvnet <
> cvnet at lawton.ewind.com> wrote:
>
>
>
> You could try autostereograms, such as the examples on my Scholarpedia
> page
> <https://protect-au.mimecast.com/s/oO48C91WPRTROqjmUE0rVx?domain=scholarpedia.org>.
> Not everyone can get them, but they're pretty effective for those who can.
>
>
>
> All the best,
>
> Christopher
>
>
>
> On Fri, Mar 20, 2020 at 9:35 PM Lester Loschky <loschky at ksu.edu> wrote:
>
> Hi Everybody,
>
>
>
> If you teach Sensation and Perception, and are currently preparing to
> teach it remotely, you may have the same question I have: how can you
> demonstrate stereovision remotely?
>
>
>
> As preface, the following are methods I have used in in-person classes to
> demonstrate stereo vision:
>
>    1. an actual stereoscope and example stereoimages to share with
>    students (including the classic Julesz square tile random-dot-stereogram
>    image)
>    2. example stereoscopic lenticular lens images to share with students
>    3. red/green anaglyph images with sets of cardboard & plastic
>    red/green anaglyph glasses
>    4. Google Cardboard plus cell phone to share with students
>    5. random dot autosterographic images
>    6. touching two pen tips together using two eyes versus one eye
>    7. learning about crossed vs. uncrossed disparity using two fingers at
>    different distances
>
> Unfortunately, my students don't uniformly have access to the apparatuses
> required for 1-4 above.
>
>
>
> Re. # 3 (red/green anaglyph images), I've thought of having students order
> a single pair of red/green anaglyph glasses online.  However, it appears
> that the cardboard and plastic ones can only be purchased in bulk. (I guess
> they're too cheap to sell individually.)  They also might not arrive in
> time, but students could still enjoy them once they get them.
>
>
>
> Re. #4 (Google Cardboard), I recall getting a free Google Cardboard from
> the NYTimes several years ago.  However, they are now no cheaper than $5
> (Irisu, of India), and likely wouldn't arrive in time.
>
>
>
> Regarding option #5 (random-dot autostereograms), I have found that since
> seeing random dot autostereographic images in depth requires perceptual
> learning, a large proportion of students don't manage to learn (within the
> short time period given in a single class period).  (Of course, many
> students may have a lot of time on their hands now, so they might keep at
> it long enough to learn to perceive them.  But there will definitely be a
> good proportion of students who don't try long enough to learn, and so
> don't get it.)
>
>
>
> #6 (touching two pen tips together) is definitely something that can be
> done remotely.  However, it doesn't have the "Wow!" factor of other
> demonstrations.  It is more of an "oh, really..." experience to realize how
> much worse you are with one eye than two.
>
>
>
> #7 (using two fingers at different distances to teach crossed vs.
> uncrossed disparity) can definitely be done remotely.  It is very
> educational, but again does not have the "Wow" factor.
>
>
>
> There is also the finger "hot dog" illusion, which can be done remotely.
> It is interesting, but quite different from all of the others in that
> stereoscopic depth perception is not involved.
>
>
>
> For the related phenomenon of motion parallax, "wiggle vision" is a very
> nice demonstration:
>
> http://www.well.com/user/jimg/stereo/stereo_gate.html
> <https://protect-au.mimecast.com/s/yE-gC0YKPviJyBz2H2LFMq?domain=well.com>
>
>
> https://www.3dwiggle.com/2016/06/28/5-wigglegrams-you-need-to-see-before-you-die/
> <https://protect-au.mimecast.com/s/z49PCgZ0N1iPByJlH3ksyC?domain=3dwiggle.com/>
>
>
>
> Of course, depth perception from motion parallax is importantly
> theoretically related to stereoscopic vision (both involve two different
> images from two different views, one seen over time (and only needing one
> eye)--motion parallax--and the other seen simultaneously (and requiring two
> eyes)--stereovision).  But it is not the same as stereoscopic vision, so is
> a separate but related issue.
>
>
>
> For the related phenomenon of binocular disparity, there is the famous
> "hole in your hand" illusion using a cardboard paper towel roll.  If
> students have a spare cardboard paper towel roll, they can do this
> remotely.  But, again, it is a theoretically related but separate issue.
>
>
>
> Any other suggestions would be appreciated.
>
>
> Best wishes,
>
>
>
> Les
>
> --
>
> Lester Loschky
>
> Professor
>
> Associate Director, Cognitive and Neurobiological Approaches to Plasticity
> Center
> Department of Psychological Sciences
> 471 Bluemont Hall
>
> 1114 Mid-Campus Dr North
>
> Kansas State University
> Manhattan, KS  66506-5302
>
> email: loschky at ksu.edu
>
> research page: https://www.k-state.edu/psych/research/loschkylester.html
> <https://protect-au.mimecast.com/s/XYyACjZ1N7ilOm0jS1y030?domain=k-state.edu>
>
> lab page: http://www.k-state.edu/psych/vcl/index.html
> <https://protect-au.mimecast.com/s/awZ8Ck81N9tYwBvnF8nvws?domain=k-state.edu>
>
>
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>
>
>
>
>
>
> --
>
> Lester Loschky
>
> Professor
>
> Associate Director, Cognitive and Neurobiological Approaches to Plasticity
> Center
> Department of Psychological Sciences
> 471 Bluemont Hall
>
> 1114 Mid-Campus Dr North
>
> Kansas State University
> Manhattan, KS  66506-5302
>
> email: loschky at ksu.edu
>
> research page: https://www.k-state.edu/psych/research/loschkylester.html
> <https://protect-au.mimecast.com/s/XYyACjZ1N7ilOm0jS1y030?domain=k-state.edu>
>
> lab page: http://www.k-state.edu/psych/vcl/index.html
> <https://protect-au.mimecast.com/s/awZ8Ck81N9tYwBvnF8nvws?domain=k-state.edu>
>

-- 
Lester Loschky
Professor
Associate Director, Cognitive and Neurobiological Approaches to Plasticity
Center
Department of Psychological Sciences
471 Bluemont Hall
1114 Mid-Campus Dr North
Kansas State University
Manhattan, KS  66506-5302
email: loschky at ksu.edu
research page: https://www.k-state.edu/psych/research/loschkylester.html
lab page: http://www.k-state.edu/psych/vcl/index.html
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