Subject: Re: Stereo .gifs

From: [email-masked] (Quentin Kelly)
Date: 16 Sep 92 06:08:23 GMT

In article [email-masked], [email-masked] (Duane Starcher) writes:
> 
> 	I have scanned five recent stereo photographs in GIF format and
> placed them in the /pub/stereo directory on  morgan.ucs.mun.ca  .
> 
> 	You will want to ftp the "readme" file in ASCII format and the
> ..gif files in binary.  I would appreciate feedback on how these display
> on your systems.  I seem to have elimated the background interference and
> get a good display of them via CSHOW (MS-DOS).
 	[email-masked]

How do I look at them? Go cross-eyed?

---

From: [email-masked] (Duane Starcher)
Date: 16 Sep 92 11:55:25 GMT

Yes, indeed, the stereo .gifs on morgan.ucs.mun.ca are arranged
for you to "go cross-eyed."  For those who missed the notice, the gifs
are in the pub/stereo directory and are all in X-viewing format.

                    duane              duane
S                  @                    @
T                    morgan.               morgan.
E                ucs.                ucs.
R                     mun.                 mun.
E                ca                 ca
O                  (  Virtual           ( Virtual
                     Juggler  )         Juggler )

---

From: [email-masked] (Juhana Kouhia)
Date: 17 Sep 92 15:27:40 GMT

>are in the pub/stereo directory and are all in X-viewing format.

When I try cross-eye, my eyes go out of focus.
If I move the images close to my eyes, then
it is more sharper (but still blurry), but then
I get artifacts from my eye classes; they obscure
the images.

Parallel-eye viewing works ok, I can see stereo images from any
distance (not too close), and very easily.
(Also, I prefer this mode more, because it is the sleeping position,
say. That is, more natural than cross-eyeing.)

You cross-eyers, please:
Does your images get blurry when you view them?
What are your viewing distances for the images;
that is, can you cross-eye 10 feet images at distance of 30 feet?

Juhana Kouhia

---

From: [email-masked] (Duane Starcher)
Date: 17 Sep 92 22:15:03 GMT

>
>When I try cross-eyed, my eyes go out of focus.
>

	That is the "big trick" for most lensless stereo viewing, whether
straight ahead or crossed:  we have to focus close while looking far and
vice versa.  I could do cross-eyed easily and took the better part of a
week to master straight ahead viewing.  Cross-eyed is a bit more tiring
on the eye muscles at first but, like any other muscle, spaced practice
will improve stamina.  Don't expect either form of viewing to come
automatically or without effort.  We have too many habits to overcome
when we hope to get control of our vision in this way.  Keep at it.  Try
to view my sig in both modes until you can do it either way.

                    duane              duane
S                  @                    @
T                    morgan.               morgan.
E                ucs.                ucs.
R                     mun.                 mun.
E                ca                 ca
O                  (  Virtual           ( Virtual
                     Juggler  )         Juggler )

---

From: [email-masked] (Juhana Kouhia)
Date: 18 Sep 92 06:33:19 GMT

In article <[email-masked]>
[email-masked] (Duane Starcher) writes:
>vice versa.

Ah, after minute training I got the cross-eyed view to the focus.
In the straigh ahead mode the image seems to be a bit bigger
than in the cross eyed mode.

Ok, now I don't have to edit those images to the straigh ahead mode :-)

Juhana Kouhia

---

From: [email-masked] (Chris Brewster)
Date: 18 Sep 92 15:39:18 GMT

Duane Starcher writes:

   That is the "big trick" for most lensless stereo viewing, whether
   straight ahead or crossed:  we have to focus close while looking far
   and vice versa. ...

Does anyone make eyeglasses with the right optics for this purpose?
What's needed would be similar to the optics in a steropticon.  A set
like this could be versatile, especially for anything appearing in
print.

Chris Brewster
[email-masked]

---

From: [email-masked] (H}kan Andersson)
Date: 18 Sep 92 15:23:33 GMT

>When I try cross-eye, my eyes go out of focus.

Yes. This requires TRAINING. But, as most things, once mastered it is easy.

>If I move the images close to my eyes, then

Dont move them closer. Keep at a few feets distance at least (works for me)

>I get artifacts from my eye classes; they obscure

The problem is that the eyes are so USED to focusing up-close when the
eyes cross. It takes a LOT of effort to work that reflex out of the
visual cortex. But once done, the results are great. I run REND386 with
cross-eye view and it works fine for me.

DONT however try to move the image closer. It will only destroy your
possibility to sharpen, forcing your eyes to cross til' they pop ;-)

>distance (not too close), and very easily.

This is very interesting, and I dont have a good physical explanation.
I have NEVER IN MY LIFE been able to diverge my eyes to do parallell 
viewing. EVER. God was i mad when the stereo pairs in The Renderman
Companion wasn't cross-eyed :-(

>say. That is, more natural than cross-eyeing.)

No. IT is not. You have to diverge your eyes, wich is by NO MEANS natural.
I simply can't do it. Crossing them is natural - you do it every day to look
at objects really close.

>Does your images get blurry when you view them?

NO!

>that is, can you cross-eye 10 feet images at distance of 30 feet?

Probably. I can successfully cross-eye almost anything.

One thing one must "learn" when cross eying is to expect that the
image looks 'small'. When you have a book in fromt of you with
a stereo X eye image, the image may appear to be two inches high.

But when you cross-eye, the eyes think the image is in the space
between the book and you (close to you) and once you have mastered
the urge to FOCUS close, what you will "see" (or rather "feel") is
a small (3/4 inch) image hanging at your nose.

At least I do.

>Juhana Kouhia

BTW, hi juhana. Havn't heard from you lately...

/Z
-- 
!! The ANSWER   : 42     ("Hitchhikers Guide to the Galaxy" - Douglas Adams) 
!! The QUESTION : 0x2b | ~0x2b   ("Hamlet" - William Shakespear) | Dont Worry -
!! The EMAIL    : [email-masked]  The PHONE: +46 16 96460    | Mail Zappie!

--
!! The ANSWER   : 42     ("Hitchhikers Guide to the Galaxy" - Douglas Adams) 
!! The QUESTION : 0x2b | ~0x2b   ("Hamlet" - William Shakespear) | Dont Worry -
!! The EMAIL    : [email-masked]  The PHONE: +46 16 96460    | Mail Zappie!

---

From: [email-masked] (Dave Huddle)
Date: 18 Sep 92 18:36:30 GMT

In article <[email-masked]>, [email-masked] (Chris
Brewster) writes:
|> Duane Starcher writes:
|> 
|>    That is the "big trick" for most lensless stereo viewing, whether
|>    straight ahead or crossed:  we have to focus close while looking far
|>    and vice versa. ...
|> 
|> Does anyone make eyeglasses with the right optics for this purpose?
|> What's needed would be similar to the optics in a steropticon.  A set
|> like this could be versatile, especially for anything appearing in
|> print.
|> 
|> Chris Brewster
|> [email-masked]

I've used cheap drugstore reading glasses for this.  These allowed me to have my
eyes focused and aligned for infinity viewing, but the glasses bring the image
into focus at a reasonable reading /viewing distance. 

However, with practice, I've learned to freeview walleyed or crosseyed with
equal ease without the glasses.  Of course, using the glasses gives me a bigger
image.

You can purchase an inexpensive lorgnette style of stereo viewer from Reel 3-D.
It's optics are like those of a stereoscope, i.e. magnifying lenses set so that
your eyes can see a stereoview with homologous points spaced wider than your own
interocular distance.

Also, there are adjustable front-surface mirror stereoscopes available.  These
work well with larger images.

There is also the Nesh viewer.  To use this viewer, the images are placed one
above the other, and the prismatic viewer allows one eye to look up at a slight
angle while the other eye is looking down.  Your eyes converge and focus
normally.
 
With this system, the eye to image distance is proportional to the vertical
size of the image.  The View-Magic viewer mentioned in this newsgroup recently
has nonadjustable front surface mirrors which allow one to view stereoimages
placed one above the other, but for this viewer, the maximum image height is
about 4 inches.

Note:  Stereoscope=an instrument with two eyepieces through which a pair of
photographs........are viewed....The two photographs are seen as a single
picture...having depth or three dimensions.

Stereopticon=a kind of slide projector designed to allow one view to fade out
while the next is fading in.

	Dave  [email-masked]

---

From: [email-masked] (Juhana Kouhia)
Date: 18 Sep 92 19:36:52 GMT

In article <[email-masked]> [email-masked] (H}kan Andersson)
>possibility to sharpen, forcing your eyes to cross til' they pop ;-)

Yep, this is what I have scared.
Remember the guy from the old b&w short films, who always kept his
eyes crossed, etc.  -- uh oh.

>No. IT is not. You have to diverge your eyes, wich is by NO MEANS

Hmm.. actually yes; but not much with the RenderMan Companion images
and ViewMaster, etc.
I learned the parallel-eye viewing by closing my eyes, and then
quickly opening them so that the rest position (parallel-position)
didn't vanish.

>I simply can't do it. Crossing them is natural - you do it every day
>to look at objects really close.

I change my believ; never actually checked the thing.

>a small (3/4 inch) image hanging at your nose.

Sounds reasonable explanation.

>BTW, hi juhana. Havn't heard from you lately...

Hi. E-mail rules ok.

Juhana Kouhia