3D destroying sense of scale in movies

Yes, it can happen. Generally speaking, the closer something appears to be (the more it pops out), the smaller it will seem to be. The further away it appears, the larger it will seem to be. It's easy to see on the PC where you have full control of the 3D effect. You can move an object forward and backward in 3D space, and while the physical size of the object on the screen will stay the same, it's perceived size with the glasses on can be small with it popping out, to gigantic when pushed off to the horizon.

Stereoscopic vision is only good out to about 200 yards. Beyond that, the only information your brain is getting with stereoscopic vision is, "it's at least 200 yards away." The closer an object is, the greater the disparity between the image in the left and right eyes, and the greater stereoscopic 3D effect. If a director wants to show a landscape, the majority of the scene will be far away and the 3Dness will be fairly minimal (though you get a realistic sense of scale). If the director decides a more engaging 3D effect is desirable, he can move the landscape closer. Actually what is done is the distance between the left and right cameras is increased. The result is you view the landscape as if you were a giant, or conversely, as if the landscape has been miniaturized. You can better make out the curves of each hill, and you can pick out each individual tree with the enhanced 3D effect. It looks very real and tangible, but as a very real and tangible model.

As you can see, it's something of a trade off. Personally for me 3D is all about realism, and preserving the scale is important. But, I can see why directors might choose to destroy it for an enhanced 3D effect. It's an artistic decision, which I don't like.

3D doesn't work well for distance shots. Has to do with the phenomena that causes railroad tracks to converge as they get further away from the eye.

There are many more limitations when shooting in 3D then there are shooting in 2D. Sometimes the film makers forget this. Has to do with their individual experience level shooting in 3D or converting scenes to 3D that don't convert well or at all. There are two ways to create depth when shooting in 3D. Positive - the image appears in front of the screen (popout). Negative - the image appears behind the screen. Directors choice as to which he will use to convey what he wants the audience to see.

That's why most productions hire a Stereographer when doing a 3D movie. To tell them what will work and what won't.

Then you have the phenomena where watching 3D seems to shrink the images. That's why it is always recommended to sit closer then normal, whether in a theater or at home, when watching 3D content.

I also don't like the "dollhouse" effect, which is the term many 3D gamers use to describe it. In PC gaming, i configure 3D for realism and things that are far away appear very distant and appropriately large. I wonder if its the fact that the PC monitor is right in front of you, presenting a 3D world that extends from the very close screen, outward. I think it more just that its set correctly. like what Lee said, that its perspective, like his train track example. Ie, you can have God Zilla appear in front of the screen and look realistically large, only if it just a small part of him, like just his hand. Putting all of God Zilla would give him the physical size of the screen or less. What i hope they try is to forget trying to make the key scene elements at screne depth as go with full time, always-on pop-out so that you'd have things that are meters away from the camera, appear meters away from you to. That would mimic the PC 3D experience, which is far, far superior than movie at this point. Using a Pc in 3D in like having a window to a holodeck basically and it only limited by resolution and the current state of graphics technology.

Interesting thing i noticed in trying out a 27" 3D monitor after having used a 46" 3DTV for a year is that the perceived depth skyrocketed up despite being on the same setting as before. I believe its because of perspective as well, since when i pull the monitor closer, which i do for a greater field of view, the percieved depth falls back in line with the 46" which is at the back of my desk and offers the same field of view and thus angle of the pixels from the eye (size of image), as when pulling the 27" closer. Thus it seems that movie makers could increase perceived depth by using a lens that made objects in the distance appear slightly smaller.

It helps to have a really big TV

I've noticed this in 3D gaming, especially now that I've got an actual 3D monitor.

The "deeper" the depth effect, the smaller the scale is. It's like having a tiny camera inside, like you said, a diorama, instead of a huge environment.

I see videos on YouTube that people have captured in 3D playing games, and it amazes me how they're able to play like this. The separation is so huge that anything more than about five feet away from the convergence point is physically straining to focus on, it fees like I'm crossing my eyes.

Personally, I've found the best results are the most subtle. The settings in the games I'm playing are very "shallow" by comparison, but give a decent sense of scale, and a big boost in immersion. That's the line we have to tread with this stuff. At a certain point, immersion becomes gimmick, and ends up pulling the user out of the experience instead of drawing them further into it.

Some filmmakers understand this, and it seems to be mostly the ones that are shooting natively in 3D, where the director and cinematographer can directly assess the look of the scene (Prometheus is a great example of this). As opposed to a conversion, where a bunch of suits in a boardroom keep saying "It needs more POP!!"

Hehe, not always. An example of a strange sense of scale I ran into was an early scene in Transformers 3 in IMAX (big enough TV for ya?). Some transformers were walking on a huge structure and they looked like little toys in 3D. That's kind of appropriate I guess, since transformers are meant to advertise toys, but I'm not sure that was the intended effect.

I find this curious, because it would describe it the opposite. With the depth set to the maximum realistic value (objects in the distance are separated 6.5 cm on the screen), objects on the horizon such as buildings look appropriately distant and large. Once that's set, I find it's the convergence setting that really determines scale. With high convergence (if "high" is even an appropriate term), foreground objects appear closer, perhaps with some popout, and consequently smaller, as the size of the object on the screen doesn't grow any larger. Lower convergence, and objects appear deeper, further away, but their size on the screen doesn't get any smaller, so they consequently appear larger.

I experienced this problem of scale yesterday firing up GTA IV on PC for the first time. I first set the convergence relatively high, with Niko appearing just slightly beyond my screen (90"). I played about an hour this way, and while the stereoscopic 3D effect was vivid, I realized I wasn't getting a realistic sense of scale. So, I lowered the convergence, and magically the scale of buildings, cars, and the city came into view. The 3D effect was less acute, but well worth the trade off.

Perhaps screen size does have a role to play here?


I think there's some misconceptions about proper depth/separation settings in the PC community. My understanding is the max separation for depth is 6.5 cm (or whatever your interocular distance is), regardless of the size of the screen. Other people say it's relative to the size of the screen, and the more separation the better as long as it's comfortable. Here's a thread on the Nvidia 3D forums advocating very high depth settings (and me trying to put the brakes on it) resulting in some huge on screen separation. I know tory40 here has recommended allowing for a little divergence for objects in the distance, so there might be some value to it, but clearly some people out there just think more is better and play that way (perhaps what you see on Youtube is extreme popout rather than depth though?).

Where does that 6.5cm number come from? I've never really looked into what's "technically" accurate, I usually just adjust depth until it "looks right". Ah, never mind.. I just looked it up. At that width, your eyes are effectively looking straight ahead, perfectly parallel to each other, as they would at something that's very far away, and anything closer, the eyes cross slightly.

For me personally, I seem to prefer shallower depth. Maybe "shallower" isn't the right word, because things in the distance still look like they're in the distance. But the depth isn't thick enough to ever draw me out of the experience. I find it works better when it's more subtle. I'll have to try that "accurate" setting and see what happens.

Thanks for the tip.

Wow.. you're right. I just tried it in Warcraft. At "max" separation, it puts it right around 65mm, which is right where my eyes are. At first, my eyes didn't want to focus on it (probably my brain telling them that the screen's only three feet away). But once I was able to "lock on", so to speak, everything kind of snapped into place (that's actually what it felt like.. hehe), and it felt very natural.

I am getting a bit of ghosting, but that may be something I can tweak away. Bloom settings or something that's fighting with NVidia (Mine's a passive monitor, so I'm having to futz 3D Vision with the EDID override anyway).

Still, a lot of those 3D videos I see on YouTube are still messed up.. hehe. Convergence issues, maybe.

I don' t think the screen size will help. What bothers me is the distorted perspective or the reversed relationship between the size of object and its distances - i.e. the closer it is from me, the smaller it appears.

Number 14 above, LOL.

There are indeed some poor quality 3D movies made with a mix of 2D and 3D shots, e.g. Pirates of the Caribbean: On Stranger Tides 3D
Edited by valley_nomad - 6/10/12 at 9:21pm