This is an excerpt from my book
Science Toys You Can Make With Your Kids.
The full text of the book is available in
Science Toys.
- Quick and simple laser communicator.
- Improved laser communicator.
- Make your own 3D pictures in minutes.
- Building the impossible kaleidoscope.
- Building a simple spectroscope.
- How to video tape through a microscope.
- Going further:
- Lasers and holography.
Make your own 3D pictures in minutes
In this section you will see just how easy it is to take pictures
that show realistic three dimensional (3D) images.
The pictures can be viewed in three ways: by crossing your eyes,
by focussing you eyes at infinity (called the 'parallel' method
because the two lines of sight are parallel), and with an
inexpensive (or homemade) 3D viewer.
The viewer is nice because
it takes a little practise to see the images with the first two
methods, and most people find the viewer easier and more comfortable.
Taking the pictures
This is actually the simplest part. You can use any camera you
have available. Just take a picture, then move the camera to the side
a little bit, then take another picture. That's all there is to it.
I like to use a tripod, but some people just shift their balance from
one foot to the other for each shot.
The next step is to place the two pictures next to one another
and cross your eyes to see the 3D view. For cross-eyed viewing,
the picture that was taken from the right side goes on the left,
and the picture taken from the left side goes on the right.
If you have an instant camera, the pictures (of course) can be viewed
right away. I like to use a digital camera, because the pictures are
higher quality, and I can still see them right away on the screen.
Even if you use a standard film camera, the pictures can be digitized
on a scanner (either at home or through the services of your film
processing company) and then pasted together to be viewed on the
screen or printed on a color printer.
To view cross-eyed, keep the pictures at a distance where you can
comfortably focus on them. Slowly cross your eyes until instead
of two pictures, you see three. The center picture will be in 3D.
It takes some practice. If you find yourself straining your eye muscles,
you may be trying to focus on the air between you and the pictures,
where your eyes are aiming. Relax, and try again, letting your eyes
focus on the pictures, but cross so the left eye sees the right picture,
and the right eye sees the left.
Once you get the hang of it, you can do it comfortably right away, and
can view the pictures as long as you like, shifting your gaze from
items in the foreground to items in the background effortlessly. The
3D effect is stunning, not only because of the stereo effect, but because
there is twice as much information getting to your brain. It is almost like
being there.
In the pictures below, start with the smallest ones, and only go on
to the larger versions when you can comfortably get the 3D effect.
Sometimes it helps to start farther away, and move closer only when
your eyes are properly positioned and you can see the 3D effect.
Cross your eyes to view these images in stereo 3D
The view from my home office window
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Some people find it easier to aim their eyes at infinity rather than
to cross them. Because two light rays coming from infinity are parallel
when they reach your eyes, this method is called the 'parallel' method.
The problem with the parallel method is that the pictures must be the
width of the distance between your eyes. That's not very big, and that
limits the detail you can get on a computer monitor. It is less of a
problem with photographic prints (since they contain a lot more detail
per square inch than a computer monitor).
For parallel viewing, the pictures are reversed from cross-eyed viewing.
The picture taken from the right is on the right, and is viewed by the
right eye.
In the photos below, find the size that makes the pictures on your
monitor close in width to the distance between your eyes. Then relax,
and let your eyes drift through the pictures as if they were viewing
a mountaintop far in the distance. You will gradually be able to see
three pictures as with the cross-eyed method, and like then, the center
picture will be in 3D.
For me, it sometimes helps to get very close to the screen, so the
pictures are very blurry. This makes it so that each eye is very
definitely looking at a different picture. Then, when I have a blurry
3D image, I slowly back away from the screen until it comes in focus,
being careful not to lose the 3D sensation. When you are very close
to the screen, it will look like the two pictures have merged into
one. As you back away, you will be able to see the other two pictures
flanking the 3D center image.
View these pictures with eyes parallel (looking at infinity)
My house
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A path to the treehouse
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The view from my home office window
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All of these photos so far have been done with the 'hyper-stereo'
technique, where the camera positions are separated by more than
the distance between the eyes. For true stereo, try holding your
head completely still (rest it against a wall for example), and
hold the camera up to one eye for the first shot, then up to the
other eye for the second shot. These 3D images will work well for
objects that are nearby, and will not give the exagerated 3D for
distant objects that you see in the images of the lake in the
photos above.
For very close-up objects, you can move the camera by less than
the distance between your eyes. Now, instead of seing the 3D
effect behind the plane of the picture, the image seems to float
in mid-air between you and the screen or paper. For this to
work well, you may need a special close-up lens on your camera.
However, sometimes just shooting the picture with a magnifying
glass taped over the camera sun shade will give very good results.
If you do want to play with the hyper-stereo effect, remember that
the brain finds it easiest to see 3D images if the distance from the
camera to the object is 30 times the distance between to two camera
positions. If an object is 30 feet away, the camera position for the
second shot should not be more than 1 foot from the position of the
first shot.
The pictures below are done in true stereo, holding the camera first
to one eye, then to the other. The subject is the treehouse bridge
between two trees in my yard. It is 70 feet long and 45 feet above
the ground. You can see a little bit of my house in the background
in one of the pictures.
Cross your eyes to view these images in stereo 3D
The treehouse bridge from the other side
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View these pictures with eyes parallel (looking at infinity)
The treehouse bridge from the other side
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Remember, for the parallel viewing, each half of the picture must
be about as wide as the distance between your eyes. A little smaller
is usually OK, but bigger won't work. I am including some big images
just in case you have a remarkable computer monitor, or you wish to
print the pictures out and view them with a viewer.
Using a viewer to see the pictures
There is an inexpensive viewer available from a company called
3DViewMax
that makes viewing these images very easy and comfortable.
They will send you the viewer by first class mail, so it may
arrive as soon as the next day.
The viewer is a simple pair of plastic prisms (with a bit of
magnification also) in a folding cardboard holder that keeps
the pictures at the proper distance. The prisms make it
easier for your eyes to view parallel format stereograms.
You can use the viewer to view pictures directly from the
computer screen, or you can place your own pictures next to
one another in the viewer. I print out mine on a good color
printer on premium paper. The trick is simply to tell the
printer to print the stereogram so it is 6 inches wide. This
is because the 3-D ViewMax viewer is designed for 6 inch
pictures.
If you are having your own photographs printed for you, have
them printed 3 inches wide, so the stereogram will be 6 inches
wide when they are side by side.
It is a little difficult to build this kind of viewer yourself.
The magnification is not strictly necessary, so the viewer can
be made by putting a small wedge prism in front of each eye.
These prisms can be made by sanding and polishing small pieces
of clear plastic, but this takes some skill. Another way to
make a viewer is with small circular mirrors. The mirrors are
oriented 90 degrees from each other, and separated by the same
distance as your eyes. When you look into the mirrors, the left
eye will be looking left, and the right eye will be looking right.
The pictures are not stuck together in this viewer, but are
placed near the operator's shoulders, the left view on the left,
and the right view on the right. Such a viewer is more cumbersome
to use than the 3-D ViewMax, but it is easier to explain to
a younger child how it works, and being home-made, it might
make a better science fair project.
Click here for information
about the camera I use.
For more information on light and optics, see the
Recommended Reading
section.
Send mail to
Simon Quellen Field
via
leven@netroglycerine.com
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