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Photograph by Amy Crilly

HOMEBREW DIGITAL 3D MOVIES

Build your own stereo video camera and 3D viewer.

By Eric Kurland

The author shoots a movie of the photographer with his 3D dual-camera rig.

I have two eyes. And because of that simple fact, I also have stereopsis, the ability to perceive depth. When I was about 7 years old, I gazed into a View-Master toy and saw an amazing three-dimensional picture, and I was hooked. Today, I create 3D videos, using various homebrew camera rigs and displays. I’ll introduce you to a few of my devices, but first, a quick history lesson.

In 1838, British scientist and inventor Sir Charles Wheatstone theorized that seeing with two eyes together is what allows us to see in 3D. Wheatstone deduced that each eye observes a slightly different view of the world, and our brain fuses these two perspectives together, interpreting the parallax differences as depth. He called his discovery stereoscopic vision (literally meaning “to see solid”) and built an optical device, the stereoscope, that allowed three-dimensional viewing of pairs of drawings.

With the invention of photography, and later cinema, real-life images could be captured with two lenses and viewed in 3D. The popularity of stereoscopy has persisted over the years. In the 1890s, arcades offered 3D peep shows as entertainment, and the handheld stereoscope was a common item in home parlors — the TV of the Victorian era. The 1950s and 1980s both saw 3D movie “booms” come and go, due to the technical limitations of the times. And currently, in the age of digital video, stereoscopic 3D is seeing a major rebirth.

My own foray into 3D video began a few years ago, after I attended the monthly meeting of the Stereo Club of Southern California. Many of the photographers at the meeting had pairs of digital still cameras mounted side by side for shooting 3D photos, and it occurred to me that I could build a similar hand-held rig for use with small camcorders.

Shooting 3D

Starting with a pair of Sony Handycams, I set out to build a stereoscopic rig. My plan was to make the distance between the lenses, called the interaxial, equal to my interocular, or the distance between my eyes. This would give a natural-looking 3D depth to my footage, and would allow me to view 3D while shooting, just by looking through both camera’s viewfinders. Putting the lenses so close required removing the hand strap from the left camera.

I attached the cameras to a metal bar using quick- release mounts for easy removal, in order to access the tape and battery compartments. I fashioned a bracket from some spare parts to hold both cameras securely at the top and keep the lenses aligned. Inspired by director Mike Figgis’ steering wheel-like camera stabilizer (the “Fig Rig”), I bolted together a pair of photographic flash bars with handgrips, salvaged from a flea market dollar bin, and created a “handlebar” stabilizer. This allows me full mobility with the rig, and puts the center of rotation between the two cameras.

To control recording, I use a device called the 3D LANC Master. Developed by Dr. Damir Vrancic of Slovenia, the 3DLM connects the cameras via the LANC ports and provides simultaneous control of most camera functions. It also keeps the video recording in sync by continuously polling the tim- ing frequency of one camera, and adjusting the frequency of the other up or down to prevent drift. This is very important when shooting 3D, as any time disparity between the camcorders will result in nonmatching left and right views. Schematics and software for the 3DLM are open source under a GPL and are available for free.

Viewing Live 3D

With my camera setup complete, my next task was to build a portable stereoscopic video monitor, so others could watch live 3D during shooting. In movie theaters, stereopsis is achieved by projecting left and right images through two oppositely oriented polarizing filters onto a reflective screen. By viewing through 3D glasses made from matching polarizers, each eye sees only the corresponding projection. I decided to use the same principle for my monitor.

I started with two small LCD monitors capable of showing NTSC video, the kind that are strapped to the back of car headrests. The video output from each camera is input to one of these monitors. Because LCDs have a polarizing layer, these displays appear black to one eye and visible to the other when viewed through polarized 3D glasses. I found that the monitors had a clear plastic protective sheet glued over each LCD. These had to be carefully peeled up and removed, as they were depolarizing the light from the screens.

On one display I needed to flip the picture horizontally like a mirror image, so I opened the case and wired pin 62 of the PVI-1004C LCD controller chip to ground. I attached the LCD displays to each other at a 90° angle, their screens facing inward, and mounted a piece of half-mirrored glass between them. This glass superimposes the reflection of one screen on top of the other. When viewed through polarized glasses, the reflected image and its polarization are reversed, each eye sees only one screen, and we have live 3D video of whatever is being shot.

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Illustration by Eric Kurland

Thanks to binocular vision, when we look at the scene above from the vantage point of the glasses (top left) we see a slightly different view in each eye (bottom left and right). Our brain fuses these images together (top right), interpreting the differences as stereoscopic depth.

Editing 3D

Shooting with two cameras creates two individual video files, which are digitized into the computer for editing. First, I use the freeware application Stereo-Movie Maker, developed in Japan by Masuji Suto, to correct misalignments in my footage, which can cause eyestrain.

In StereoMovie Maker, I am able to load both the left and right videos and visually transform, scale, and rotate them while viewing in 3D with anaglyph glasses. Anaglyph is the method in which the two pictures are combined into a single image with one eye in red and the other in cyan. Primarily used in printed stereoscopy, anaglyph also provides a means of viewing depth on any computer screen using inexpensive red-cyan glasses.

Once satisfied with the alignment, I save my videos as a single file, formatted side-by-side in a split screen, and twice as wide as a normal video picture. I prefer this format, as it ensures that the two views always remain in sync throughout the editing process. The footage can be cut together in any standard video editing program. My system is PC-based, so I use Adobe Premiere, but the same techniques would apply to a Mac Final Cut Pro system. One thing to take into account when editing 3D is that drastic depth changes between consecutive shots can cause eyestrain.

To watch my completed movies in 3D, I use Peter Wimmer’s excellent Stereoscopic Player program, a full-featured media player for stereo video files that converts on-the-fly to the many different viewing formats required by stereoscopic displays and projectors. Both Stereoscopic Player and StereoMovie Maker are Windows-only applications, but they will run on Intel Macs running Windows.

Showing 3D

In order to show 3D video to audiences, I have a dual- projector setup, just like the 3D theaters of the 1950s, using two projectors, polarizers, and a silver screen. The only real difference is that my projectors are small DLP digital models, and my “film” is a file played back by computer. This arrangement works well for large audiences, but I also wanted some method of carrying my 3D movies with me to show at a moment’s notice — a portable stereoscopic media player.

The Sony PSP looked like it would be the answer. The PSP can play MPEG-4 files from a flash memory card and it has a nice, wide screen — wide enough to hold side-by-side-formatted left and right images.

In fact, the PSP is just about the same size as a standard vintage stereo card. I decided it would be cool, and somewhat steampunk, to mount a PSP onto a circa-1904 stereoscope.

As luck would have it, the PSP fit almost perfectly between the two card-holder wire clips. I didn’t want to physically alter the viewer, as it’s an antique, and I wanted the PSP to be removable, so I cut two loops of thin velcro strapping, just long enough to go around the PSP and hold it firmly to the slide bar.

To get my videos onto the PSP, I converted them to x264 compressed MPEG-4 files at the PSP’s screen resolution of 480×272 pixels, and copied them to a PSP Memory Stick. Sure enough, side-by-side video files played on the PSP and viewed through the stereoscope’s eyepiece are seen as a single three-dimensional movie.

The whole setup works perfectly. I can easily carry around a bunch of my homemade 3D movies on a Memory Stick in my pocket, and quickly show them to people through the “PSPscope” — a perfect marriage of 19th- and 21st-century technologies.

1. Build the 3D dual-camera rig.

1a. On one of the video cameras, remove the hand strap. This will be the left-eye camera.

1b. Attach the quick-release mounts to the bottom of the camcorders. Make sure that the mounts are perfectly straight, and tighten them down with a screwdriver or a coin. Position the cameras as close to each other as possible on the twin-camera bar, and tighten the thumbscrews until both cameras are rigidly secure (Figure A, next page).

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1c. Optional: If you have the hot-shoe microphone extenders, place them on the cameras and tighten the thumbscrews. Attach the extenders to the 6" flat steel bracket by placing bolts through the bracket and tightening a wing nut onto each bolt (Figures B and C). The mic extenders should be parallel. Make sure that the camera lenses are aligned.

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1d. Optional: Create a camera stabilizer by placing the flash bars end to end and attaching them to the bottom of the twin-camera bar with the handgrips pointed upward (Figure D).

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MATERIALS

FOR THE 3D DUAL-CAMERA RIG:

Matching pair of compact video cameras Any pair of camcorders will work, but the 3D LANC Master will maintain sync only on certain older Sony MiniDV cameras. Mine are Sony DCR-PC100s.

Twin-camera mounting bar from a specialty photography store

Quick-release camera mounts (2) 3D LANC Master camcorder controller Build your own from the schematics at dsc.ijs.si/3dlancmaster or order one pre-assembled from inddd.com.

Screwdriver

Hot-shoe microphone extenders (2) (optional) These were an accessory with the camcorder microphones.any 2

6" flat metal bracket (optional)

Adhesive velcro squares (optional)

Camera flash bars with handgrips (2) (optional) Any 2 should do; mine are a mismatched pair from a flea market.

Dog training clicker (optional)

FOR THE LIVE 3D MONITOR:

Audiovox EX50 5" LCD video monitors (2) You should be able to use other LCD panels, but you’ll need to check the polarization.

5"×7" half-mirrored glass aka flat glass beam splitter. You can use a cut piece of window glass but the results may not be as good.

Short length of sheathed wire such as telephone wire

Self-adhesive velcro squares ½" velcro strapping 10"×6" piece of plywood 1½"×8½"×3½" metal L-brackets (2) I had these in a scrap parts bin; you’ll need to find a similar substitute or perhaps use wood blocks instead.

½" wood screws (6)

Linear polarized 3D glasses There are 2 types of polarized 3D glasses, linear and circular. Only the linear kind will work with these LCD panels.

Precision screwdriver set Phillips and flathead

Fine-tipped soldering iron and solder Magnifying glass

FOR THE PSP STEREOSCOPE VIEWER:

Sony PSP

Holmes-style stereoscope vintage or new

½" velcro strapping

Scissors

Pliers

Adhesive rubber foot or nut and bolt (optional)

Electric drill (optional)

Photography by Eric Kurland

1e. Remove the cameras from the bar. Insert blank tapes and charged batteries. Place the cameras back on the bar. Use velcro to attach the 3D LANC Master to the rig (Figure E).

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1f. Connect the 3D LANC Master cable to the cameras’ LANC ports (Figure F). Power up the Handycams, use the 3D LANC Master’s controls to reset the cameras and get them in sync, and you’re all set to record.

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TIP: If you can’t get a 3D LANC Master, you can still shoot 3D video with your twin camcorders. Use a dog training clicker to make a sync “pop” on your soundtrack. In editing, you can use the clicker peaks on the audio tracks to align the videos. Just be aware that on long takes your scenes may drift out of sync.

2. Make the live 3D video monitor.

2a. Open the case of one of the LCD monitors. First, use a small flat-head screwdriver to pop the rubber feet out of their holes, and remove the 4 Phillips-head screws from the case; 2 of these are under the hinge, so rotate the hinge until you see the rubber feet. Make sure to note which screws go where, as they are different sizes (Figure G).

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2b. Carefully separate the 2 halves of the case. Remove the 2 Phillips screws holding down the printed circuit board (PCB) below the screen (Figure H). Very carefully flip over the PCB. Locate the LCD timing controller chip, a 64-pin IC marked “PVI-1004C.” Using a magnifier, find pin 62 and follow its trace to a small board-mounted resistor. Carefully solder a short piece of wire from this resistor to the ground point on the PCB, next to the ribbon connector (Figure I).

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2c. Close up the case, replacing the screws and rubber feet.

2d. Using the thinnest flat-head precision screwdriver, pry up a corner of the protective plastic sheet covering the LCD screen (Figure J). Slowly peel the plastic from the case. Repeat with the second LCD.

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2e. Place the half-mirrored glass against the hinged base of the first monitor so that it extends over the display. Peel and stick several velcro squares onto the base around the glass (Figure K). Repeat with the second monitor, using the opposite halves of the velcro squares.

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2f. Remove the glass and align the second monitor so that it faces the first. Press the 2 bases together, fastening the velcro.

2g. Cut a length of velcro strap long enough to encircle the base with a few inches of overlap. Wrap the strap around the base tightly and fasten it to itself (Figure L).

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2h. Make a platform to hold the monitors. Using wood screws, fasten the L-brackets to the plywood so that they create a 2¼" opening (Figure M). Fit the monitors into the opening so that they stand upright, then bend each one back on its hinge 45°, so that the 2 form a 90° angle.

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2i. Slide the glass between the bases of the LCDs (Figure N). It should clear the velcro squares and fit very snugly.

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2j. Attach the power supplies, connect the video inputs of the LCDs to the video outputs of the cameras, and power everything up. Look down through the glass at one LCD, and you should see the other display reflected in the glass (Figure O). Tweak the angle of the monitors until the images are perfectly superimposed. Adjust the brightness levels of the panels until they match.

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2k. Put on some 3D glasses and you can watch live stereoscopic video.

3. Make a PSP stereoscope.

3a. Make sure your PSP has the latest system firmware that supports playing full-screen MPEG-4 files. To check for this, go to the PSP’s system menu and select Network Update.

3b. Cut two 10½" lengths of velcro strap. Loop each piece, and overlap the ends 2½", fastening securely (Figure Q).

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3c. Place the PSP on the sliding bar of the stereoscope, between the wire card-holder clips. If the PSP doesn’t fit, use pliers to bend the wires.

3d. Holding the PSP firmly in place, slide a velcro strap over one end of both the PSP and the sliding bar (Figure R). The fit should be tight, but still allow you to move the strap on and off easily. If necessary, adjust the overlap to tighten or loosen the strap. Fit the second strap on the opposite end.

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3e. Position the straps right at the edges of the screen without obscuring it (Figure S).

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3f. Optional: Because of the weight of the PSP, the sliding bar has a tendency to slide off the back of the stereoscope. To prevent this, stick a rubber foot on the main bar, near the end.

3g. Save your 3D videos as PSP-compliant MPEG-4 files, using x264 compression, at a resolution of 480×272 pixels. Place your files into the root directory of a Memory Stick Duo. Fire up the PSP, load a side-by-side stereoscopic video, and enjoy a 3D movie.

RESOURCES

Stereo Club of Southern California: la3dclub.com

3D LANC Master free schematics and software: dsc.ijs.si/3dlancmaster

StereoMovie Maker free download: stereo.jpn.org/eng/stvmkr

Stereoscopic Player: 3dtv.at

Eric Kurland is an award-winning independent filmmaker, President of the LA 3-D Club, Director of the LA 3-D Movie Festival, and CEO of 3-D SPACE: The Center for Stereoscopic Photography, Art, Cinema, and Education. Operating out of a Secret Underground Lair in Los Angeles, he specializes in 3-DIY (do-it-yourself 3-D) and consults on every stage of 3-D production and postproduction, from development through exhibition. His 3-D clients have included National Geographic, Nintendo, and NASA’s Jet Propulsion Laboratory. He has worked as 3-D director on three music videos for the band OK Go, including the Grammy nominated All Is Not Lost, and he was the lead stereographer on the Oscar- nominated 20th Century Fox theatrical short Maggie Simpson in The Longest Daycare. In 2014, he founded the nonprofit organization, 3-D SPACE, which will operate a 3-D museum and educational center in Los Angeles. He sometimes wears a gorilla suit and space helmet.

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