8mm Forum: How to do proper 3D digital video ...

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Posted by Osi Osgood (Member # 424) on July 16, 2014, 12:26 PM:

Hey folks ...

I'm going to do some 3D experimentation.

I now have two of those wonderful "FLIP" ULTRA HD digital cameras (they shoot at 720p). I'm going to make a wood foundation and place the two cameras at slightly different angles, at the same distance as the human eyes, and then screw that onto the tripod.

Beyond that, I'm not sure as to how to pursue this further. My digital editing software allows for me to sandwich both elements together, but ...

1. What kind of glasses should I use? Polarize or the classic blue/red or some other variety?

2. What processes should I use to "sandwich" the two shots together? i.e. should I place the right field one frame or so behind the left field of vision?

I thank you for your advice ahead of time.

Posted by David M. Ballew (Member # 1818) on July 16, 2014, 03:06 PM:

Osi, the answer to your questions depends on whether or not you plan to use a 3-D TV. If the answer is yes, you can probably sandwich the images in side-by-side format on a memory card or some other such device, using free StereoMovie Maker software available online. The 3-D TV I have can “interpret” side-by-side images and display the results in ordinary 3-D, viewable with the television’s accompanying glasses.

I happen to use side-by-side format in connection with my still stereoscopic images I shoot as a hobby, but I have not done a lot with motion video yet.

If you do not plan to use a 3-D television, then no doubt red-and-blue anaglyph is your best bet. And guess what? StereoMovie Maker lets you do that, too. If you go this route, check out the Berezin Stereo website for some fine quality anaglyph glasses with plastic frames.

StereoMovie Maker software will also allow you to tweak your convergence, about which more later.

As for your filming rig, if you plan to do any kind of filming in close quarters, I recommend getting your cameras as close together as possible. In fact, I recommend placing them closer together than human eyes, which are on average 65 millimeters apart. I have found that an interaxial (lens-to-lens distance) of 45 to 55 mm results in beautiful imagery without excessive parallax.

Mount your cameras exactly parallel to each other. You can achieve this by aiming them at some very, very distant object—the moon, let’s say—and centering that object on both viewscreens.

Then apply what some old-timers call “the rule of 30.” Make sure that the closest object to your camera comes no closer than 30 times your interaxial. So if your lens separation is, say, 50 mm, make sure the closest object comes no closer than 1500 millimeters. That is, of course, unless you specifically want a “pop out” effect. Then bring the object closer (within reason), but try not to let it touch either of the vertical edges of the picture, as this generally spoils pop-out effects.

When you go into StereoMovie Maker, you can adjust the convergence. You’ll adjust the imagery so that the closest “non pop-out” objects look like they have zero parallax—that is, are not “doubled up.” That will be your plane of convergence, or your screen plane. Objects at that point look like they are right at the plane of the screen. Objects closer than that point look like they are “popping out,” like the Paddle Ball Man in House of Wax. Objects farther away than that look like they are somehow inside or behind the screen. Beautiful.

There is a lot more to be said. A lot more. I am encouraged that you are experimenting with 3-D and would love to hear about what you discover. There are books available out there for free online. Foundations of the Stereoscopic Cinema by Lenny Lipton is one of the all-time best, but be warned, it is fully of tricky algebra and trig. But like the great 3-D pioneer Ray Zone told me, the key with the hobby is to experiment, have fun, and don’t let any one else’s rigidity stand in the way of your own voyage of discovery.

Posted by David M. Ballew (Member # 1818) on July 17, 2014, 03:04 PM:

Osi, it occurs to me that I ought to explain why I suggest leaving the lenses in parallel during shooting, rather than “toeing them in” or converging them:

It is a known thing that converging lenses creates geometric distortions in stereoscopic pictures. You want individual left and right picture elements in your final video to shift laterally, purely horizontally in relation to each other, depending on the amount of parallax. You don’t want them to shift vertically, or diagonally, or do any sort of rotation in relation to each other. The best and simplest way to achieve this is to put your lenses parallel to each other, then set your convergence in post. StereoMovie Maker lets you do just that, which is why I keep coming back to it as an important potential tool for you, Osi.

Do me a favor, if you can: When you get your two-camera rig built, post a picture of it. I really love seeing any kind of 3-D camera rig, but most especially the ones fellow hobbyists have built for themselves. I hope you are having a lot of fun with this, once you get it underway.

Posted by Osi Osgood (Member # 424) on July 18, 2014, 12:11 PM:

Would you happen to have a link to "Stereo Moviemaker"?

I have Serif editing software. I wonder if I take the left and right and switch them to the red and blue spectrums, if they will work properly for 3D. I'm not sure of that will work though, as I do want them to have the glorious color as well, and not a brownish mess, though 3D!

Posted by David M. Ballew (Member # 1818) on July 18, 2014, 04:01 PM:

Osi, the link I have is http://stereo.jpn.org/eng/stvmkr/.

They spell it oddly, StereoMovie Maker, perhaps to make it possible to obtain a trademark. So if you do a Google search, maybe it helps to run "StereoMovie" together as one word. I mean, maybe. :-)

It's been a while since I noodled around with StereoMovie Maker, but my recollection is that it has a pretty robust method of creating "color anaglyphs." That is, you can use the familiar red-and-cyan transmission system, but they will have tweaked it in such a way that more of your subject's natural color will read through. It won't look like a muddy brown mess-- at least, we hope not, right?

One more point: In your first posting, you mentioned something about having one frame behind the other. If by this you mean should you play the left and right images one frame out of sync, the answer is an emphatic no. That will only result in needless eyestrain.

Given the method you intend using, your synchronism may possibly be a little "wild." That is, your cameras will be running at the same speed (whether that's 24 or 30 fps), but the "shutters" may not be perfectly in phase. So there is liable to be a small amount of asynchronism between your left and right images. This is not ideal, but it is not fatal, either. But deliberately playing the left and right images one frame out of sync is a big no-no, and doesn't fall into the category of "rigidity that can and should be ignored," a la the late Ray Zone.

Posted by Pete Richards (Member # 2203) on July 18, 2014, 05:15 PM:

Hi Osi, I've been doing 3D Production since to 90s, it is so much easier now.

First question is, what will you be viewing them on?
CRT TV, Plasma, LCD, DLP, 3DTV?
Projector or TV?

To encode the video into 3D you have a few main options.

CRT: Field sequential Video, one video stream goes into the odd fields, the other into the even fields. You end up with alternating horizontal lines of left-eye/right-eye.
Requires LCD shutter glasses to view.
Muxing the streams is easily achieved in VirtualDub using the following script:
AVISource("yourvideo.avi")
SeparateFields()
left=selecteven().process....
right=selectodd().process....
interleave(left,right)
weave()
Then make sure you encode your output as interlaced.

3DTV: Most 3DTVs also support over/under or side-by-side 3D, you you simply encode your two video streams to a squeezed over/under or side-by-side format and then select the corresponding mode on your 3DTV

LCD/PLASMA/DLP Non 3DTV or projector, for these you are stuck with either frame sequential 3D, and an appropriate decoder box and LCD glasses, or the old Anaglyph (red/blue, red/green, red/cyan glasses).
These ones work very well and let you watch any 3D content on a 2DTV, including your own movies, 3D games and 3D Bluray etc.
http://www.3d-vip.com/#!products/ch4v

As for software, my preferred choice is the viewer and muxer from here:
http://www.3dtv.at/Index_en.aspx
They have trial versions, and it is the best I have used.

Other options include Cineform, the free gopro version might work with your camera, download it and try it out, you can merge two video streams into a variety of 3D video formats.
http://gopro.com/software-app/gopro-studio-edit-software

Plus the aforementioned AviSynth you can easily output any 3D format using a script.

You absolutely want the cameras to be as in-synch as possible, even being slightly out of phase can be enough to cause both literal and figurative headaches [Smile]

Make sure both cameras are locked to manual exposure and have all settings the same.

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