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First crack at 3D Stereography!


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#1 Mike Donis

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Posted 04 May 2010 - 01:05 AM

Hello all!

Here's a test scene I shot with a home-built stereo rig and two DVX100s side-by-side. You'll need to go to my actual channel to be able to access the drop-down list to choose your ideal method of watching it in stereo - I think it defaults to cross-eyed, which is probably the best way if you can get your eyes to work like that.



I'm hoping to shoot more 3D! I'd love to hear thoughts on what you feel works and what you feel doesn't visually in this piece.

Best

Mike
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#2 Russell Scott

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Posted 04 May 2010 - 11:49 PM

Hello all!

Here's a test scene I shot with a home-built stereo rig and two DVX100s side-by-side. You'll need to go to my actual channel to be able to access the drop-down list to choose your ideal method of watching it in stereo - I think it defaults to cross-eyed, which is probably the best way if you can get your eyes to work like that.



I'm hoping to shoot more 3D! I'd love to hear thoughts on what you feel works and what you feel doesn't visually in this piece.

Best

Mike


Hi Mike, what is your intended transmission format? i.e. do you hope to put this on a TV or screen? If so, your camera separation is too much. A DVX rig is about 13cm side by side (?) which means for semi comfortable stereo on a tv you'll need the zero parallax at ~4m away(and nothing in front of that!). For close character shots with a dvx you'll definitely need a mirror rig (you can get suitable ones for the dvx for about 3k i think).

You've also chosen a lot of shots with strong foreground elements, more specifically, elements coming out of the screen. You want to minimise this as much as possible, especially with strong stereo. The example I'll point to is at 2:40. The foreground element is both way too strong and acts as a distraction, your eyes are drawn to it rather than the action, also as you pan the camera left and right, the foreground element cuts the screen, which -particularly for foreground objects - is not good. At 2:51 you have an element in one eye and not in the other, this = pain for the view. You also need to watch your reflections - in a couple of the shots there are stray reflections in one eye and not the other.

hope that helps in some way...
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#3 Mike Donis

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Posted 05 May 2010 - 12:21 AM

Hi Russell,

Thanks for your reply, indeed it is helpful. Yes, the side-by-side DVX test was something I did because I had access to two DVX100s for free. I definitely find the interocular far too great for this type of scene - it also made us need to blow up the image significantly to fix convergence issues which also lost a lot of image quality for our DVD version. You can't tell as much on Youtube with their tiny windows, but it's quite soft on a larger television.

You mention wanting to avoid elements coming out of the screen - would it perhaps be less distracting, considering this scene is already shot, to digitally adjust the convergence to the foremost element, and let the viewer converge their own eyes to focus farther into the screen where the actors may be? I'd imagine that would be even more distracting (with this given footage) and the only solution is to keep that sort of thing out of the frame altogether henceforth, unless it's totally contained in the shot?

I really appreciate your notes.

Best,
Mike
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#4 Russell Scott

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Posted 05 May 2010 - 02:05 AM

You mention wanting to avoid elements coming out of the screen - would it perhaps be less distracting, considering this scene is already shot, to digitally adjust the convergence to the foremost element, and let the viewer converge their own eyes to focus farther into the screen where the actors may be? I'd imagine that would be even more distracting (with this given footage) and the only solution is to keep that sort of thing out of the frame altogether henceforth, unless it's totally contained in the shot?


Its not really going to help that much, adjusting convergence only changes where the depth starts and stops, not now much depth you've locked into the scene. In this case the problem is the depth and there isn't really a 'post' solution. Having said that, you very rarely want objects coming out of the screen. Generally you want to be staring 'into a window'. For various reasons images coming out of the screen are more taxing than those going back. Pushing convergence too much also has other problems especially when you have strong perspective cues (and you convergence doesn't match those cues). you can see that when she opens the drawer at 0.12. The perspective strongly conflicts with the convergence you've chosen. (best shown using the 'parallel' mode on youtube)

At a glance I'd say your stereo is about a minimum of 10x too strong and for some of the close scenes about 50x. One trick you can use to get away with having too much stereo is to film with a close background. So that even though the depth is too strong, the amount of depth visible in the scene is limited (this is probably why when you 'blew up' the image it worked. Generally digitally zooming in stereo simply increases the overall stereo)...
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#5 Mike Donis

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Posted 05 May 2010 - 01:28 PM

Its not really going to help that much, adjusting convergence only changes where the depth starts and stops, not now much depth you've locked into the scene. In this case the problem is the depth and there isn't really a 'post' solution. Having said that, you very rarely want objects coming out of the screen.


In this instance though, if instead I digitally converged the shots so that the foremost element was whatever is closest to the camera, do you think that would be worthwhile? Meaning it would produce the window effect, even with the hyper-stereoscopy. I'd imagine the converged section of the frame being not what the content of the scene asks you to focus on would also produce a lot of eye strain....

When shooting in stereo are we virtually forced to never include anything in the foreground that isn't contained perfectly within the frame, and is that just a nature of the beast? What are your thoughts?

Edited by Mike Donis, 05 May 2010 - 01:31 PM.

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#6 Russell Scott

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Posted 05 May 2010 - 06:33 PM

In this instance though, if instead I digitally converged the shots so that the foremost element was whatever is closest to the camera, do you think that would be worthwhile? Meaning it would produce the window effect, even with the hyper-stereoscopy. I'd imagine the converged section of the frame being not what the content of the scene asks you to focus on would also produce a lot of eye strain....

When shooting in stereo are we virtually forced to never include anything in the foreground that isn't contained perfectly within the frame, and is that just a nature of the beast? What are your thoughts?


I don't think its worth converging the shots, simply because the extreme nature of the stereo in the shot means it won't help. In this case it isn't just the foreground elements that are the problem. Often there are objects captured in one eye and not the other, or captured with very different perspective vanishing points; converging the stereo differently won't help.

The general answer is yes, you are forced to never include objects coming out of the screen. You can do it occasionally with quickly moving objects because the mechanism with which the eye tracks objects is slightly different at pace (poor explanation, sorry!).
You can also get away with objects in front of the screen if your stereo is minimal, but its best to avoid cutting the screen (left or right sides) an even then, generally inadvisable.
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