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Active 3D vs Passive 3D In Terms of Video Game Performance

April 30th, 2012 · 22 Comments · Other S3D Tech

It seems that there is a strange misconception going on around that since passive 3D monitors use only half of the vertical resolution for displaying the frame for each eye you are supposed to get higher fps in a game. But this is far from the truth, because even though each frame for each eye displayed with a resolution of 1920×540 on a passive 3D display is actually still rendered in 1920×1080 resolution and then the extra lines are being discarded. As a result you have the same performance requirements for rendering the stereoscopic 3D image on either passive 3D or active 3D monitor, even though you are getting a bit lower resolution on the passive 3D solutions when viewing the result.

Rendering at Full HD resolution on passive 3D solution allows you for example to save stereoscopic 3D screenshots or 3D video from a game with full resolution, though this might not work on all stereoscopic 3D solutions. It also allows you to get better quality of the image without having to resort to very performance taxing solutions for anti-aliasing as lowering the vertical resolution can lead to more jagged edges. Using the extra visual information that has already been rendered can help process the stereoscopic 3D image that is going to be displayed, so that it will look better, even though the extra vertical lines from each frame are still being discarded. That does not help much when you have very small details or small text displayed using passive 3D setup, but still can help improve the overall visual quality without much of a performance loss. In the end you can expect to get pretty much the same number of FPS on the same system running either a passive 3D display or an active 3D solution for gaming in stereoscopic 3D mode. Actually with passive you can be getting a bit less fps due to the extra processing of the images before they are being displayed on the screen, but the difference is very small, so you will hardly notice it.

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22 responses so far ↓

  • 1 oshin // Apr 30, 2012 at 19:02

    What about the fact an active display needs double the number of frames rendered as there is one for each eye ? Surely this has a big impact compared to the passive method, which outputs half the frames of the active method, but may require more processing to split the image.

  • 2 Bloody // Apr 30, 2012 at 19:54

    The active 3D solutions does not need to render more frames, they render the same amount of frames as passive 3D solutions, the difference is in how they are being displayed and thus the performance requirement for rendering the same thing in passive 3D or active 3D is pretty much the same when talking about games.

    Here is an example: for both methods you have 60 frames rendered per eye, or a total of 120 frames per second. However for active 3D you have the first frame displayed for the left eye only, then the second for the right eye only etc. And for passive 3D you have both the image for the left and right eye displayed at the same time with each of them just being with half vertical resolution. In the end you get 60 fps (if your GPU can handle it) in stereo 3D mode with both solutions rendering the same number of frames.

  • 3 oshin // Apr 30, 2012 at 21:10

    Yes, but surely the passive solution has less overhead than the active as the 2 frames have half the vertical resolution ?m thinking of this from A pc perspective with a 120hz screen as I know consoles are limited to 60hz. Forgive me if im missing something. I have just ordered a 3d screen and I have found the process exhausting as there are so many options. Its like being back in the days of 3dfx vs opengl vs glide.

  • 4 Bloody // May 1, 2012 at 00:16

    As I’ve said with passive 3D they are rendered as full frames and then just displayed with half vertical resolution.

    When talking about consoles, most games supporting stereo 3D output are either optimized to be not so demanding, so they can cope up with S3D or the more likely solution – when in stereo 3D mode some sacrifices are being made in the level of details as compared to when playing the same game in 2D mode.

  • 5 3dtv.com // May 1, 2012 at 01:31

    Passive has less overhead, but is the quality there? I think that’s the biggest question people are asking themselves. Because in the end, it’s the quality that a consumer determines whether or not the prices is worth it.

  • 6 AzzX // May 1, 2012 at 08:02

    Regardless of resolution, isn’t Passive rendered at effectively 60hz full frames whilst active is rendered at 120hz (60hz split)

    I may be wrong but the 120hz requirement does take a performance hit if it does indeed require double the frame rate – compare it to a playtv setup on a standard LCD and measure the fps to see what I mean.

  • 7 Bloody // May 1, 2012 at 11:47

    As I’ve said already in both passive and active 3D solutions you are rendering the same amount of frames per eye – 60 and at the same resolution. The difference is how you output them with each solution, but in the end you still get 60 different frames per eye displayed to the viewer, or a total of 120 frames fro both eyes. With active yo get them displayed as a sequence of frames first for the left and then for the right eye only, meaning you still get 60 fps per eye and the glasses do the separation, not 120. And with passive 3D you get them displayed s 60 fps, however each frame contains both the image for the left and for the right eye and the glasses separate them. Due to the way passive 3D works by putting together two 3D frames in a single 2D one you get the half vertical resolution for the image for each eye.

    So if you put on a polarizing filter on a 120Hz LCD panel making it passive 3D compatible you can get 120 frames per eye in 3D mode on it, that is why passive 3D displays are at 60Hz as this is enough to display 60 frames per eye in stereoscopic 3D mode.

  • 8 Oshin // May 1, 2012 at 13:12

    Sorry it only hit me last night what you were saying, that passive solutuions still have to render 2 frames at 1920×1080 and then scale them to 540. This would make sense. Just to muddy the waters though I read an article last night about nvidias 3d vision that says it doesnt render two seperate frames, but instead applies an algorithim to one frame to create the effect. Has anybody done a comparison study yet ?

  • 9 LoneThread // May 1, 2012 at 22:50

    Oshin, I mean this is the nicest possible way. Please stop posting until you’ve done some proper reading/thinking.
    Active/Passive. It makes no difference, you still have to RENDER from both angles to create the 3D Image.

    I have no idea what you’re referring to in regards to 3D Vision not rendering 2 different views. Maybe your confused by the whole 2D to 3D conversion stuff which really is awful and generally bad for 3D’s reputation.

  • 10 Bloody // May 1, 2012 at 23:43

    Oshin, you might’ve read something about the game Crysis and their 2D + Depth approach for rendering the stereo 3D image with less performance loss. This is an alternative that doesn’t produce such a good result as full dual frame rendering, but it also “costs” much less in terms of performance. The difference however is only in how the frame for the other eye is being generated, in the end the game engine still outputs two full frames, one for each eye. So in this case the stereoscopic 3D rendering does not lead to such a performance drop, however the rendering requirements for displaying the same thing on an active 3D or on a passive 3D display would still be pretty much the same.

  • 11 Bal // May 2, 2012 at 04:17

    Sorry, but this post is trying to defend something which is – if true – just plain lazyness on the part of nvidia. If the card indeed renders twice the pixels just to throw them away, this is just a plain waste of resources.

    Nothing indicates that this is necessary. The few people taking stereo screenshots once in a month does not worth taking close to 100% more resources for each people using passive setups.

    The argument that it improves quality is only true if there is a correct scanline antialising within the driver before discarding each second line. I have never seen an official statement that this is happening.

    And this is a false argument: ANY rendering would benefit from a higher resolution. You could argue similarly that it is worthy to render 32000×16000 in 120Hz active 3D, because after downsampling it nicely improves picture quality. But it is not by chance that this way is rarely chosen.

  • 12 Bloody // May 2, 2012 at 10:26

    This is not only how Nvidia does it, but how everyone is doing it. I’m not sure if Nvidia is using the extra data for some sort of image improvement or just discarding it, they are not pushing a lot their “Optimized for GeForce” and there isn’t much information about it. Other solutions however are taking advantage of the extra image data before discarding it and combining it with the image for the other eye. And regarding downsampling, yes it is true that improves quality, but that is only if you downsample to lower resolution and not discard extra information in order to lower the resolution.

  • 13 LoneThread // May 2, 2012 at 23:06

    @Bloody – I heard everywhere that Crysis had no 3D Vision support and even on AMD setups, only the gun was 3D. The rest was all just 1 layer with separation in the distance. Is this correct? Its been awhile since I last read about it on the nVidia Forums.

  • 14 vittorio // May 3, 2012 at 17:01

    I tested this with tridef and nvidia 3dvision for my passiv 3DTV.

    Tridef does have an option called soft interlacing. With this option enabled you get very good extra anti-aliasing for the half vertical resolution. Without this option enabled it seems they simply throw away half of the rendered lines. An option for not rendering these thrown away lines would be nice for better FPS.

    Nvidia does not have an option, but they use the rendered lines for anti-aliasing. I think tridefs anti-aliasing gives better results. But this could be a placebo effect though, since i have never seen them side by side, and i bought tridef after nvidia only because of this option.

  • 15 Rodolfo // May 3, 2012 at 18:45

    I have a active 3DTV Plasma Panasonic 50″. It´s great, but I tried a passive TV in a shop…. it´s so confortable !!!!! I would like to test one with Skyrim !

  • 16 Newbiesmith // May 5, 2012 at 05:22

    The results of a rather extensive scientific study comparing passive vs. active is posted at displaymate.com, which is a very reputable site.

    The results of this study determined that passive 3d technology does not deliver half the resolution, and proved, this basically by performing eye chart tests. If passive 3d displays were 1/2 the resolution, it should have been impossible to read smallest letters that were only 6 to 10 pixels in height. Not only were letters as readable on the passive 3d monitors as they were on the active, but they were sharper and clearer on the passive 3d sets.

    That said, we have both an active and passive 3d displays. For 3d gaming with my Nvidia GTX video card equipped pc, our active 3d monitor (with Nvidia active 3d glasses) does seem to work best.

    For watching movies, console gaming, and most 2d viewing, our passive 3d monitor is far superior, in every way imaginable. The picture above does not portray an accurate picture.

  • 17 badelhas // May 6, 2012 at 05:39

    probably because the active display is worst than the passive one. What are the models?

  • 18 Johnny // May 6, 2012 at 20:43

    In the iz3D driver you can select whether the additional lines should be used for antialiasing or not, it’s called “interlaced (optimized)” or just “interlaced”. But you cannot disable theie superfluous lines’ calculation. Theoretically this might be possible, but I guess it’s very difficult to implement this. Maybe some games with native 3D like Avatar have optimized their passive calculation, but I doubt this.

  • 19 dgrambo // May 8, 2012 at 01:54

    With passive movie playback, you dont have to render anything. Just find properly interlaced video and play it. The set doesnt even have to be in 3D mode. No ghosting and no eye strain. Just slightly apparent horizontal interlacing at times. Best compromise. Picture on my LG passive is awesome. I can see the pores in the actors skin no problem and theres no blurring at all. My Epson PJ on the other hand, runs at 120 but softens the image and has visible crosstalk and looses 70 percent of its brightness. Active over HDMI is either 720p or 24 fps max, take your choice. Lastly, just go to Best Buy and compare the active sets to the passive. First off, the one pair of secured active glasses will probably be broken or dead. If they do work what youll see is a dark indistinct image, riddled with artifacts. Maybe only one eye working. Now check out the passive. Grab a pair of glasses out of the bucket and what youll see is a bright, stable, artifact free 3D image that is detailed, crisp relaxing to look at. You may notice some gentle interlacing on some scenes but details will be excellent and by this time youll forget youre wearing the lightweight glasses and start grinning like a kid.

  • 20 dgrambo // May 8, 2012 at 01:55

    Video games, not so much.

  • 21 Airion // May 8, 2012 at 05:59

    About the Displaymate active vs passive shootout, it used poor active sets that have a lot of ghosting. It appears designed to hand a win to passive. It also makes the common mistake of treating 1080p 2D and 3D as the same thing, when 1080p 3D is two different 1080p 2D images, twice the number of pixels. So with passive, you get 540 in one eye and 540 in the other, add them together and you get full 1080p! The math is rock solid. Just don’t apply the same math to active, or else passive will look bad!

  • 22 VicentiuB // Jun 3, 2012 at 02:28

    I compared 3D Ready TV with Active vs Passive technology
    First , tha Passive 3D technology divide the resolution by 2 , when i watch 3d passive TV i see horrible horizontal lines all over the screen in background picture , it like an interlaced lines like on cathodic tube TV , this look horrible when text are writed on the screen ! I recomend 3D active TV’s for full resolution 1080p 3D not divided by 2 like low cost passive 3D TV , sure in waiting for Toshiba 55 inch 3D Free Glasses NATIVE 3D TV who not need 3d glasses anymore and with High-definition 4k !

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