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When
you assemble your cross-eyed image, you need to swap left/right, since you are,
after all, crossing your eyes. It's important that you also vertically
align your images so that objects line up, and take any rotation out if one
image is rotated. Usually, if rotation needs to be taken out, you usually
only need 0.5-2 degrees, depending on how sloppy you were taking the originals
(I can sometimes be pretty sloppy taking them).Another pointer that helps in
"framing" the 3D, is to trim the left and right sides of each image (a
left/right crop) so that they agree, i.e., a foreground object should be the
same distance from the left and right sides of each image. Notice here
(and you can click on the image at left for more detail) that the statue in
front is in the same left-edge/right-edge location on each picture. This
has the effect of making the edges of the picture float in the foreground as
well (the "frame", or the black edges and gutter).
Shutter Glasses
You can also use LCD shutter glasses to view 3D more directly on your monitor.
I have not used them in quite a few years, but last time I did, there was no
real standard and each came with their own viewing software. That said,
it's a great way to view 3D with not much strain on the eyes.
The way they work is by alternately displaying the left, then the right image
while blacking out the opposite eye, all at a high enough speed that you won't
really notice it. Most video cards (I think) now support it, but since I
don't use them myself, I don't have a lot of advice here.
Anaglyph
The red/blue, or anaglyph, works well for daytime pictures that don't have a lot
of red in them. You can view anaglyphs on your computer screen, or have
them printed by an online print service (Kodak, Shutterfly, Snapfish, etc...) or
at most photo stores, including Wal-Mart.
To
create an anaglyph image, you need to put both images into an image editor such
as Adobe Photoshop. My example uses Photoshop, but there are probably
several high-end editors that can do the job.
Select the left image, go to Channels, and select only the red layer. Type Ctrl-A to select the entire image, then Ctrl-C to copy the red layer (which will appear in grayshade when only that layer is selected).
Then, go the the right image, go to Channels,
and again select the red layer. This time, type Ctrl-P to paste the Left
image's red layer, replacing the Right image's red layer. Keeping the red
layer selected, look at the left side of the red layer band in Channels, and
there will be a little eyeball. Go to the empty square just above that
eyeball and click on that, which will make your view full-color. In most
cases, your red layer will be shifted, so you need to select the Move tool, or
type "v" on the keyboard. Then you can drag the red layer with the mouse
or move it with the cursor keys. Select a foreground object in the picture
to line up. You can also be wearing your anaglyph glasses as this point to
help in optimizing the 3D picture.
Once you have done this, you will want to crop off the non-overlapping part to
make it a clean picture. Then, make sure to save off under a new name, so
you don't destroy the Right picture original (I've done this once or twice
myself). Voila! You have a screen-viewable or printable anaglyph
image!
Slides
Finally, if you have slides or want to project them with a projector or handheld
viewer, skip to the next section. If you have only digitals, read on.
Now that I am fully digital, I still want to be able to have a slide show to
show a room full of guests. To do that now, I can get slides directly made
from digital images (at the time of this writing) at
www.iprintfromhome.com. They
offer a relatively inexpensive option ($2.49/slide), at least when you consider
the cost of film, developing, and then the fact that you only put some of them
in the slideshow, you have a lot of waste.
To prepare your images, keep in mind that 35mm slide film is a 3:2 ratio, and
most digital cameras (as of 2005) are still a 4:3 ratio, just like non-HD
televisions. Newer cameras do offer multiple aspect ratios, but even my
spiffy Coolpix 8800 only offers one image mode in 3:2 while offering many
variations in 4:3. As a result, you will need to crop your image (or let
iprintfromhome do it for you- I do not suggest this for 3D) to a 3:2 ratio, at
which time you can optimize them yourself by vertically lining up the images and
adjusting the left/right crop.
For
portable, or handheld viewing, I use a Star-D viewer (model 2020). Since
I purchased this one in 1990, they disappeared from the market for quite
a while. They have recently come back and are sold online by Berezin
Stereo Photography Products. He has several types available and
will even customize them for unusual slide formats.
Since I don't use "normal" 3D slide mounts, which are 4 inches long by about 1.5 inches, I had to modify my older viewer. I sliced out the left and right side limits that keep the slide from falling out to allow more lateral movement of the two standard 35mm slides to line up the images. With horizontal slides, about 85% of the vertical frame is visible in the field of view. The problem is with vertical slides. About 1/3 of the image is cut off. Ideally, the lens assembly should be completely severed from the back of the viewer and both mounted on a board with a deeper slot cut in for maximum field of view.
One interesting note is that some pictures actually look better in the
viewer than on the screen. The image in the viewer is much brighter and
crisper.
The silver screen is essential. A white screen will simply scatter the polarized light, completely- you will get no effect. The silver screen preserves the polarization so thoroughly that with only one image displayed, you will only see it in one eye (with a dim ghost of the image in the other eye).
The
moveable tray is important. Placing the projectors side by side presented
a problem in that the two images when overlapped, diverged from each other
at the edges. As you can see in the diagram to the right, the left
image and the right image only overlap
in the purple area. Objects at the left edge of the left image are smaller
than objects at the left edge of the right image, and hence don't line
up vertically (and the eyes have trouble adapting individually in that
direction).
Ideally, you want the two images projected along the same axis, but lacking the optics, the best way to get the projectors closes together was to stack them vertically. The upper tray Is hinged to allow the images to be vertically moved to line up for any mistakes I made when taking the photographs (I misalign about 25% of my pictures to some degree). See Figure 2 for a drawing of my tray setup and a link to instructions on how to assemble it.
Figure 2- Tray Assembly
You will still get divergence in the two images since they are not coaxial, but the divergence will be at the top and bottoms of the image, and will occur from left to right, which your eyes will easily compensate for. You won't even notice it.
To make the glasses, buy a plastic sheet of polarizing material and some cheap sunglasses. I prefer the black-framed, Blues Brother's style. Pop out the lenses. Take these lenses, keeping track of the the left and right, and with a pen trace around each one on the plastic- one horizontally, and one vertically. Do this for each pair of glasses. For purposes of this text, I will assume the left lens is horizontal. Do this for all left lenses. Cut out the left lenses and pop them into the left lens holder of the glasses. Repeat with the vertical right lenses.
Figure 3- arrow points towards screen
Finally, to set up your projectors, place the two polarizers over the lenses and turn on the projectors, facing the screen. With the glasses on, select the projector you have designated to have your left photos in and turn the polarizer until the image gets as dim as it will get in the right eye. Use tape to hold the polarizer in place. Repeat the process with the right projector, minimizing the image in left eye.
I use PVC tubing that fits around the lens and cut two round polarizers from the same material used to make the glasses.
See the figure below to see the complete setup.
I use Kodak 4600 Carousel autofocus projectors.
The screen is a silvered lenticular screen made by Da-Lite Screen Co, Inc.
The Star D viewer is available from Berezin Stereo Photography Products.
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