Date:1 August 2010
Who says 3D moviemaking is the province only of Hollywood pros? With a budget that’s a fraction of the blockbusters’, you can shoot and edit eye-popping 3D video. <br>By Anthony Verducci
I may not have access to the customdesigned 3D camera rigs or R2-plus billion budget that James Cameron had for Avatar, but that shouldn’t mean I can’t produce my own movie with breathtaking – well, okay, at least passable – 3D effects. True, the task may seem daunting and expensive at first. After all, the cheapest 3D camcorder on the market right now is Panasonic’s AG-3DA1 (price: about R160 000), and even that requires a constellation of specialised equipment and software to deliver usable 3D footage.
What’s more, the gear that electronics manufacturers are just now introducing to the market to edit and play 3D content requires an almost total replacement of your existing computer and AV equipment. I don’t really want to buy a new graphics card, computer screen, HDTV (which I just got, thank you very much), home theatre receiver and Blu-ray player, but I do kind of like the idea of making a cheap and easy 3D action flick starring my cat.
Fortunately for me, a hobbyist subculture has sprung up to address the unmet need for low-production-value at-home 3D moviemaking – a movement dedicated to the art of building stereoscopic camera rigs using two off-the-shelf inexpensive camcorders mounted on a rail. It started when husband-and-wife team Ron and AmyJo Proctor, both students at Weber State University, posted instructions for bolting together two Kodak Zx1 camcorders. “We kind of built it on a lark,” says Ron. “We wanted a Flip-style video camera for chasing our two-year old. They were so affordable that we decided to buy a pair. Once we had those, the jump to 3D was natural.” The Proctors used a 157-year-old process that is known as anaglyph 3D, which uses the same iconic red-and-blue glasses that turned 1950s comics into virtual pop-up books. The anaglyph process works by filtering the vision of a viewer’s left eye through a red filter and the right eye through a cyan (blue) filter. Each frame of video is produced with two superimposed images that have been stereoscopically separated, then subjected to colour subtraction in a computer image-editing program. When viewing these superimposed images through anaglyph 3D glasses, the brain interprets and combines the complementary colours, creating the illusion of depth.
The process sounds a lot more complicated than it actually is in practice. It is certainly far simpler than the two other major 3D processes currently employed by Hollywood and the electronics industry. Most 3D movies use a specialised screen and polarised glasses to deliver 3D projection, whereas the new 3D home theatre gear generally relies upon shutter glasses that are synchronised to a TV that runs at a high frame rate.
True, the anaglyph editing process can tint the colour of your video, but it works with equipment you probably already own – requiring no major investment to play back the video. Perhaps that is why it is often employed by movie studios for their own home video releases. Recent Blu-ray movies such as Coraline and My Bloody Valentine used the red-and-blue-filtered glasses.
Actually making the 3D rig is the easy part. As Ron Proctor describes it: “You can just drill some holes in a bit of scrap metal and bolt your cameras on.” An M6 bolt will thread into the tapped tripod mounting hole in most cameras. If you’re mounting to a metal bar or plate, we’d suggest cutting slots to allow for fine adjustment of the distance between the video cameras. Ideally, the distance between the two camera lenses should match the stereoscopic separation of human eyes, which is typically 63 mm. Adjustments to this separation allow for a variable depth of field, but too much separation will result in an unresolvable image.
Once you’ve created a mounting bracket (it doesn’t need to be metal; you can also use wood or plastic), it can be affixed to almost anything – tripod, bicycle, car bonnet, helmet – with whatever hardware or adhesive you prefer.
I wanted maximum mobility and minimum camera shake, so I decided to complicate the project for myself by designing and building a homemade Steadicam.
The company that makes Steadicams, Tiffen, sells the Merlin, a very nice camcorder- friendly version of its professional camera stabiliser, for around R7 000 in the USA (the company also has in the works a Steadicam for iPhones that should cost less than a quarter of that). But I was looking for a solution that was more in the R200 range. I attached the camera bracket to a makeshift gimbal I constructed by combining a plastic U-joint from an RC car with a ball bearing mounted in a 12 mm PVC handle. To keep the camera level, I bent a 90 cm piece of steel flat stock into an arc to act as a counterweight, then I made fine adjustments by attaching various weight magnets to the bar. Because of the ball bearing, the entire apparatus was able to rotate freely relative to the handle, while the U-joint allows the cameras to maintain position horizontally.
To be honest, it takes quite a bit of tinkering to get this thing perfectly level, and then keeping it level is another skill set entirely. Even with a professional Steadicam, you need to keep your arms held close to your body and walk smoothly to get the best effects.
Creating a home-made 3D steadicam rig in three (sort of) easy steps.
Setting up a 3D camera system is the easy part. Just cut a channel in either metal or wood, then mount two inexpensive video cameras using two standard M6 bolts, washers and some wingnuts. Try to match the distance between human eyes – 63 mm.
My Steadicam rig featured a makeshift gimbal formed from a skateboard bearing and a modified RC car’s U-joint. I installed the bearing inside a piece of PVC tubing, then ran an 8 mm through the length of the tube, threading it into the plastic U-joint. To cover the PVC pipe, I used a rubber bicycle handle grip.
This part was tricky. I built a counterbalance from punched steel flat stock trimmed and hand-bent into a crescent, then carefully weighted it with varioussize magnets.
When you are done recording, you should have two separate video clips that need to be uploaded (make sure to save one as “left” and the other as “right” to keep yourself organised). To edit the footage, I used Sony Vegas Pro 9, but many less expensive video-editing packages can do the job.
The first step is to load both clips into your video-editing software. Next you want to trim the video so that both clips start on the same frame. Then search for the menu option that lets you adjust colour controls (your software might call this levels or channels). You’ll know you’re in the right menu when you see sliders for the colours red, green and blue.
Anaglyph video editing is essentially an exercise in colour subtraction. For the left-eye footage, dial down or turn off the blue and green channels. For the right eye, subtract the red channel.
Once that’s complete, you need to create a composite of the two clips. (Again, the language differs with the software: some call the process overlay or blending.) That should merge the left-eye and right-eye tracks together into one. You’re probably going to want to throw on some anaglyph 3D glasses to make sure you’ve done it right.
Which brings up the question: can you do it wrong? And the answer is, sort of. You may find that, after all of your work, the 3D isn’t that apparent in your clip. Most video-editing programs allow you to artificially separate the left- and righteye channels a bit by cropping the images slightly, then redoing the composite. By skewing the stereoscopic separation, you can add depth to the resulting video without reshooting.
(After this lengthy explanation, it’s worth noting that before year-end, a Roxio-branded 3D software suite from Sonic Solutions will completely automate the 3D editing process.) In the end, my 2-minute feline flick isn’t going to break any box-office records, but the 3D effect worked. And I can easily share my anaglyph 3D clips by posting to YouTube, so that anyone with a pair of red-and-blue 3D glasses can enjoy them.
By the way, those glasses are ridiculously cheap and easy to acquire. On Amazon.com, 50-packs of paper and cellophane glasses can be had for about R200. Or, if you think that 3D video production may become a lifestyle for you, opt for the fancier, hard plastic kind for around R50 each – they’re more durable, and about as fashionable as red-andblue- tinted eyewear can be.
Transforming video of my cat into an anaglyph 3D movie was surprisingly simple. I converted the left video clip to red (by subtracting blue and green) and the right clip to blue (by subtracting red). To make the fi nished frame, I overlaid left and right into a single composite image, tweaking the position slightly to get better stereoscopic separation. Now, seen through 3D glasses, my cat leaps off the screen.