| Author | Message | ||
     Larry Elie Rating: N/A |
Electronic Engineering Times, Aug. 1 http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=166403796 http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=166403733 | ||
| M.H. Rating: N/A |
Funny sentence from the article :-): "Sharkboy uses the classic anaglyph method of red and green passive polarized glasses.However, this method has drawbacks: It requires two aligned and synchronized film projectors, it restricts the director's color palette and it creates ghosting if a viewer moves his or her head more than about 2° out of alignment. " | ||
| Larry Elie Rating: N/A |
The most impressive thing to me was; Disney is PAYING MONEY to OUTFIT THEATERS to show movies at 96 Hz..... That's not cheap! It ALSO means, DISNEY EXPECTS TO BE USING MORE 3D IN THE FUTURE. You don't modify theaters at a high price for one showing. Second, in case you missed it (elsewhere, not this article), Disney's new chairman announced that the new model for theater releases is they intend to release DVD's CONCURRENTLY with the film for theaters. Although the theaters are up in arms, Disney expects it to solve several issues; one, piracy may drop a bit as some people only get the pirated version because they can't buy the new film yet. Second, they make a LOT more money on dvd/tape sales than on theater sales. But to do that, they need another differentiator. 3D, especially at the rep rate like 96 Hz might be it. | ||
| ChrisC007 Rating: N/A |
"recalling the 1980s era of Jaws 3-D, Amityville 3-D and H_A_L_L_O_W_E_E_N_ _3_-_D_"? oooppss! | ||
| Larry Elie Rating: N/A |
Have you ever seen a 3D movie at 96 Hz? I can set up games at 96 Hz, but I've only seen one movie (2D) filmed at 90 Hz (an IWERKS short) and the difference for action was pretty impressive. | ||
| Alatar Rating: N/A |
I think they mean 96Hz playback, which is in fact standard -- at least to the extent anything is standard in this field -- for alternate-eye. Although not shot at 96Hz, a lot of 3D is *shown* at 96Hz; in fact almost everything shot for film and exhibited in an alternate-eye environment is shown this way. This is so because you have two (R & L) 24-fps sources and showing it at 48fps results in too much flicker (85Hz being about the minimum for most people in theater lighting). So one winds up using 2-2 pulldown (i.e. each frame gets shown twice). Put another way, 24fps x 2 eyes x 2 exposures per image = 96Hz. | ||
| Scott Warren Rating: N/A |
Example: Original monoscopic film projection picture sequence(antique way)-- ABCDE...UVWXY each showing at 1/24th (or 1/16th or 1/18th)sec. (very flickering) Normal monoscopic film projection picture sequence (since 1920's), aka 2:2 pulldown-- AABBCCDDEE......UUVVWWXXYY each showing at 1/48th sec. (reduces flicker to near-imperceptibility) High-quality monoscopic film projection picture sequence aka 3:3 pulldown-- AAABBBCCCDDDEEE.........UUUVVVWWWXXXYYY each showing at 1/72nd sec. (all but eliminates flicker) Very high quality monoscopic film projetion picture sequence aka 4:4 pulldown-- AAAABBBBCCCCDDDDEEEE............UUUUVVVVWWWWXXXXYYYY each showing at 1/96th sec. (eliminates flicker) If you take version 2 and alternate eyes, each eye receives 1/2 the screen time/motion, so you're down to unacceptable levels again. Can't really do version 3, because of there being an odd number of repetitions. So version 4 is the 1st workable solution for alternate eye film projection-- AL AR AL AR BL BR BL BR CL CR CL CR......WL WR WL WR XL XR XL XR YL YR YL YR each showing for 1/96th sec. (reduces flicker to near imperceptibility again) similar solution would be-- AL AL AR AR BL BL BR BR CL CL CR CR......WL WL WR WR XL XL XR XR YL YL YR YR but it's probably better motion-perception-wise to do the former Scott | ||
| Larry Elie Rating: N/A |
And what does IMAX do? Every IMAX I have seen (purporting to be 24 FPS) has VERY perceptable flicker. | ||
| Scott Warren Rating: N/A |
Non-stereoscopic imax movies can be shown at different frame rates. Many are of the type that utilize high-speed recording film to get that "fluid motion" feel with action/copter/rollercoaster stuff. Many are ~72Hz. Obviously, at this rate, they don't necessarily have to do a 2:2 type pulldown. Stereoscopic Imax movies fall under 2 categories--active & passive. Passive (polarized) would be projected (by 2 projectors--most likely) at whatever rates usual for non-stereoscopic imax films. Active projection is probably what you're seeing. If the glasses have a bad lag/extinction rate or if the emitter isn't synced correctly, you would notice flicker. Assuming they have got that worked out correctly, it could be they're showing a "version2" stereoscopic sequence (as per my analogy above), as opposed to a preferred "version4" stereoscopic sequence. Scott | ||
| Larry Elie Rating: N/A |
Pure passive; the only IMAX near me doesn't have any active equipment. Second, although several large format equipment makers CAN film at 72 Hz (IWERKS for example), my local IMAX can ONLY project at 24 Hz from either of the two projectors. All of their prints are made for that rate. Yes, I asked. And yes, they get lots of camplaints about flicker. I didn't ask the event duration (length of time the shutter was open--I don't know the film terminology, I would call it dwell time) just for the frame rate. Perhaps they just don't know their equipment? So, if they use AL AR AL AR BL BR BL BR CL CR CL CR......WL WR WL WR XL XR XL XR YL YR YL YR on a projector that can't do better than 1/24 of a second, instead of 1/96 of a second, would we not have bad flicker? Or is the 1/96 of a second just the dwell time for each shutter open event (not frame change) which is what I would have expected. After all, moving the big frame, getting it stopped, and doing it again in 1/96 of a second doesn't sound too easy. | ||
| Alatar Rating: N/A |
There are two synced projectors (or one with two rotors), so each one only has to show 48 images per second to get 96Hz total output. However, if you assume (what I call) 50% duty cycle, then consider these required steps: 1. AL is visible 2. Nothing is visible 3. AR is visible 4. Nothing is visible 5. AL is visible 6. Nothing is visible 7. AR is visible 8. Nothing is visible 9. BL is visible etc. Steps 2, 4, 6 etc above are required during the glasses switchover time. Note that this could be because the projector gate is closed, because the both eyepieces are closed, or both. It will be very short, perhaps nearly zero. Steps 1-8 have to complete in 1/24th of a second. But the switch of frame in the left eye has to occur within steps 5 through 7. Since 5 and 6 together are 1/4 of 1/24th of a second, the entire frame pulldown must happen in 1/96th of a second or slightly longer. This works because of the Imax rolling loop, the invention of which made 15-perf pulldowns possible in the first place. PS: if you think about it, these timings are the same as a standard 2D projector running at 2:2 pulldown. In otherwords, Imax really didn't have to change much to go from 2D to 3D -- they just used two synced 2D projectors. | ||
| Larry Elie Rating: N/A |
One more time; I think we are talking past each other: Yes, there is 'strobing' of the images through chopper wheels. That's true at any 2D theater using film projection too. But it doesn't change the FRAME RATE. As I read the article, the FRAME RATE is not 24 FPS anymore, but 96 FPS. The FRAME RATE is governed by the cameras (or in this case, by the rendering engine) not by the projection technique at all. They specifically talk about that to reduce flicker for the 3D by going to a higher frame rate. It isn't just the two projectors. Now perhaps the article got it all wrong. Perhaps you just get to gate the projection of 24 pictures per second and call it 96 events and not frames. In that case you are right. But EET is usually pretty reliable... I guess if this is coming out soon and theaters will be outfitted we will know for sure soon. | ||
| Alatar Rating: N/A |
Ok, I agree that we have a confusion in terminology. How about if we call the number of frames per second "Frame Rate" and the number of flashes per second "Display Rate". I don't see -- probably because I'm missing it -- where it says anything other than that the SMPTE panel may recommend increasing the standard Frame Rate to be higher than 2 x 24FPS. Quote: ------ The SMPTE spec is also expected to recommend refresh rates beyond the minimum 48 Hz of two 24-frame/second streams, to avoid flicker that causes eyestrain. Approaches such as RealD's already support "flashing" each frame two or three times to achieve virtual refresh rates of 96 to 144 MHz. ------ Apart from the obvious typo that they mean Hz not MHz and that virtually everyone -- not only RealD -- have used "flashing each frame two or three times" for decades, I don't see anything to support evidence of people (except for the old Imax HD and some amusement park stuff) currently using anything other than 24 Frames per second. Or am I missing your point entirely? After writing this, I realize I was confusing Scott's point with yours! My position is that film-based 3D theater *only* uses 2 x 24FPS, and some multiple of that as a Display Rate. The new digital 3D standard may well go higher than that. Are we on the same page now? | ||
| Larry Elie Rating: N/A |
Probably. But remember this is a fully RENDERED film. As you say; "The new digital 3D standard may will go higher than that." Quoting from the SECOND article: " Disney spokesperson said the stereoscopic technology the studio is helping to install in about 100 theaters for its upcoming animated feature Chicken Little offers better "audience comfort" than the old 3-D. That's because the theaters will use "lighter glasses, extremely high digital projection frame rates [estimated at 96 frames/second], no flicker, no [film] grain and no projection booth noise," thanks to the digital technology. " They use the term 'digigal projection frame rates' at 96 FRAMES/second. Is it clear? No, I agree it isn't because the next paragraph says: " "The [eye] fatigue level virtually disappears with our technique of triple flashing," said Joshua Greer, chief executive officer of RealD, which is said to be supplying some of Disney's 3-D technology. Triple flashing means shining light three times through each of 24 frames/s per eye, Greer explained. RealD saw no visible evidence of eyestrain in user tests, he added. " So yes, tripple flash for film, but for digital???? I suspect someone hasn't told the whole story. | ||
| Scott Warren Rating: N/A |
Especially when 3 x 24 = 72, not 96. Somebody doesn't have their facts right... Scott | ||
| Joseph L. Kleiman Rating: N/A |
I dont' know if this would help explain things better, but when Ray Zone and I visited REAL D, Josh went into a bit of detail about the tripple flashing. http://www.worldenteractive.com/realdpt2.htm | ||
| Scott Warren Rating: N/A |
Ok, what the RealD guys mentioned in that article refers to 144Hz display rate. That would be 2 viewpoints x 24 fps (stored) x 3 "flashes", or 2eyes x 72fps display rate. In my parlance: AL AL AL AR AR AR BL BL BL BR BR BR CL CL CL CR CR CR DL DL DL DR DR DR EL EL EL ER ER ER.........UL UL UL UR UR UR VL VL VL VR VR VR WL WL WL WR WR WR XL XL XL XR XR XR YL YL YL YR YR YR or AL AR AL AR AL AR BL BR BL BR BL BR CL CR CL CR CL CR DL DR DL DR DL DR EL ER EL ER EL ER.........UL UR UL UR UL UR VL VR VL VR VL VR WL WR WL WR WL WR XL XR XL XR XL XR YL YR YL YR YL YR each showing at 1/144nd sec. (all but eliminates flicker) The former sequence might be possible with film if you could hotrod the speed to that point. With digital either of the sequences is possible. Scott | ||
| Scott Warren Rating: N/A |
>>>>edit>>>> ...and the latter sequence would be preferable. Scott | ||
| Alatar Rating: N/A |
You can do the latter with film too -- and in fact that is the way it (i.e. IMAX Alternate-Eye 3d) works now and has always been done. Except that it's 96Hz with a 2:2 pulldown instead of the 144Hz with a 3:3 pulldown. There are two projectors, they both pull down a frame, and then the projector (i.e mechanical) shutters open and close -- exactly out of sync with each other -- three times before the next pulldown. (Actually the right-eye pulldown happens during the first BL and the left eye happens during the last AR) | ||
| Alatar Rating: N/A |
Added: So perhaps when they say they are "triple-flashing" it just means they have a display rate of 2 x 72 flashes / sec = 144 instead of the older standard of 2 x 48 flashes /sec = 96. Both RealD and IMAX still being at 2 x 24 frames / second, though. Does that make sense? Or does anyone believe they are really using a higher *frame* rate than 24? | ||
| Larry Elie Rating: N/A |
It won't be higher than 24 FPS if it is FILM. Most theaters will be just getting film. If the quotes can be believed, some won't be film; 'That's because the theaters will use "lighter glasses, extremely high digital projection frame rates [estimated at 96 frames/second], no flicker, no [film] grain and no projection booth noise," thanks to the digital technology.' If it's real digital, the rate depends on how good the 3 DLP (or will it be 6?) projector is. | ||
| Joseph L. Kleiman Rating: N/A |
If I'm not mistaken, for a 2K digital cinema projector to be DCI-compliant under the current specs, projection is restricted to 48fps (i.e. 2x24). | ||
| Alatar Rating: N/A |
Joseph: can you clarify that please? Am I correct that you mean 2 eyes times 24fps rather 2 flashes times 24? | ||
| Scott Warren Rating: N/A |
IIRC, that's the "minimum" acceptable for the standard (you can always sell a system that is better). And that mainly means monoscopic content. To maintain quality, any horsepower spec for stereoscopic capability would have to be double the amount for monoscopic. (Pretty sure it means 2 flashes x 24fps) Yeah, I really wish the DCI spec would have had built-in explicit support for stereo, but it didn't. I think the committees, which contained alot of studio producers/distributors, were probably worried about jacking up the equipment requirements (AND COSTS) to the exhibitors who will have to pay the bulk of the costs. Good thing is, once digital, the capabilities of these things will continually improve along with the costs lowering, so maybe DCI v2.0? will guarantee stereo3d capability. Scott | ||
| Joseph L. Kleiman Rating: N/A |
The NuVision shutterglasses (the ones used for the DLP demonstration at ShoWest), which are DCI-compliant operate at 96hz, Because of this, I believe that it's each eye at 24fps, which is then double flashed. So, it would be: AL AL AR AR BL BL BR BR.... or AL AR AL AR BL BR BL BR.... I've sent an email to DCI to clarify this. | ||
| Larry Elie Rating: N/A |
The 100 theaters will be digital. Quoting from other sources: http://www.dcinematoday.com/dc/pr.aspx?newsID=280 Frequency? Who knows. | ||
| Larry Elie Rating: N/A |
I got info it's 24 FPS tripple flashed. | ||
| Captain3D Rating: N/A |
Hi Larry Now I see the thread :-) Yes chicken Little is a 24fps rendered CG movie. I am the stereographer on the project at ILM. We are just finishing off the last few shots. Cheers...Phil |
