Re: [photo-3d] Hyper active

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

As someone else mentioned on this thread earlier, we can view hyperstereo
images without photography using a simple mirror device.  Although, I think
we all understand the meaning of this statement: that we cannot see
hyperstereo with the unaided eyes.

There is a very amusing satire on this concept in the Imax 3D film
"Encounter in the Third Dimension", which also has been released under the
title "3D Madness".

Anyway, the scene involves a simulated avatar, a three dimensional
alien/robot creature that flies around the room and acts as a foil for the
narrator and the "professor" (another satire, on the "mad doctor" character
of SF lore).  In one scene, the robot character removes his eyes and extends
them outward to extend its stereo base, and comments on the inability of
human beings to do the same.

The film is loaded with satirical humor based on stereoscopic truths and
fallacies, and is a must if you enjoy that sort of thing.   A lot of it
seems to be quite corny on the surface, especially if you just listen to the
dialog.  But, their are a lot of subtleties, primarily visual, that add a
much more sophisticated perspective.  Anyway, the film can be enjoyed on a
much higher level if you keep your eyes (both of them!) open.  Scan the
screen, checking details that you might miss if you just follow the main
action lines.

Back to the non-photography direct viewing device.   This consists of four
mirrors (as with the notorious image splitter).  Only this is sort of an
image splitter that you look through instead of photograph through.

The main difference is in the spacing of the mirrors.  In the typical image
splitter, the two outboard mirrors are spaced apart such that the optical
centerlines of them is (or ideally should be) about 65mm.

With the hyperstereo viewing device, it is the two inboard mirrors that are
spaced such that their optical centerlines are about 65mm apart.  The
outboard mirrors are spaced much further apart, the optical centerline
distance determining the hyperstereo base.  Otherwise, the configuration is
the same as that of a camera image splitter.

The results when looking at the images as seen through the center pair of
mirrors can be quite fascinating.  This is especially true with wider stereo
bases and more distant subjects, because when something is so far away that
there is little depth perception with the unaided eyes, it is possible to
make the depth impression quite exaggerated, which in some cases is quite
startling.

It will probably occur to someone that if you can look at such a device with
both eyes, you should be able to photograph through it with a stereo camera,
producing hyperstereo photographic images in a single camera, automatically
in sync.

This is true.   However, two important considerations if it is to be used in
this manner.

Although conventional cheap second surface mirrors (even plastic mirrors)
can be used if viewing is the only application, for photography only high
quality glass first surface mirrors should be used.  Also make sure that the
outboard mirrors are large enough so that parts of the image are not
occluded at the intended stereo base.

This can be determined with any stereo camera that has a removable or
openable)  back and a "bulb" or "time" shutter setting, without wasting
expensive film, by temporarily taping a frosted plastic or ground glass in
the film plane of the otherwise empty camera.

With the camera in a dark area, and the subject in a light area, observe the
images.  Having someone else hold a flashlight (electric torch if you are
British), ask them to move the flashlight around the edges of the outboard
mirrors while you observe the frosted plastic or glass.  If you see the
light from the flashlight in the image area, the mirrors are too small.

Construction of a non-photographic hyperstereo viewing device would make a
very good activity for a young student looking for a science fair project.

Even the student's instructor would probably be surprised at the results.

Of course, the student should study the device to acquire some understanding
of how and why it works.   This might surprise the instructor even more.
It might even inspire several more students (and possibly even the teacher)
to look into the science of stereography even deeper (sorry, I couldn't
resist the pun).

Who knows, maybe we will have a future stereographer or, hopefully,
stereographers.

JR

----- Original Message -----
From: "Jim Harp" <matmail2@xxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Saturday, October 21, 2000 1:51 PM
Subject: [photo-3d] Hyper active


> > Hyperstereo, on the other hand, presents us with a view that would
> > be impossible to see in any way other than through photography -
>
> Although you're correct in theory that a hyper image can present a
> view that would be impossible to see with the unaided eye, I usually
> prefer scenic views that are slightly hyper (as long as there isn't a
> tree branch at four feet.)  In real life we don't stand perfectly
> still while looking at things.  As we move our heads we get more
> information about the depth in a scene.  This information is even
> more pronounced when looking at scenery from a moving car.  Hyper
> images convey some of this increased depth, and thus might actually
> be a more natural way of reproducing some scenic views. I suggest
> experimenting a lot if you're shooting hypers.  You can "bracket"
> separation just as you bracket exposure.  You might be surprised at
> how different a scene looks with differing separations.  My favorite
> way to shoot hypers is with two synched 35mm SLRs, especially when I
> can freeze moving traffic or flying birds.  With non moving subjects
> any camera can producing stunning results.  Jim Harp
>
>
>
>
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