| Author | Message | ||
     marinus lutz Rating: N/A |
Howdy folks! "Shade 7" a 3D modeling and animation app [U$210] renders stereoscopically. I asked for more info [interocular separation controls? toe-in/convergence controls???] but either the tech guy didn't know, or it's one-size-fits-all. But... it's the ONLY stereoscopic support i know of. None of its competitors have any. The tech guy did say it works fine with that new Toshiba autostereoscopic display. CuriousLabs.com. Catch you later, Lutz | ||
| clyde Rating: N/A |
hi lutz, good info on the soft. will add it to my list. Im not sure about what you mean when you say "ONLY" software that supports stereoscopic output. do you mean Only as in Autostereo output? then perhaps maybe.. cause anaglyph and interlaced (horizntally) can be handled by plugins for software like 3ds max , maya etc. and displays like the X3D plasma one,have a bundled OpenGl VRML viewer tha will let you manipulate in realtime your3d creations. Regards Clyde | ||
| Puppet Kite Kid Rating: N/A |
A great stereoscopic plugin would be a monster to create. I hope Polar Express just taught us some great stuff, but I'd still add a thing or two. With 3D CGI, not only do you need to aim your cameras parallel to infinity to create *perfect 3D*, you also have to animate your stereo base (which was done really well in Polar Express). The only additional thing that I'd do after that is animate the horizontal parallax. It would be extremely difficult, if not impossible, to animate both the stereo base and the horizontal parallax at the same time (instant brain freeze ;-). I have done very little CGI, but just creating a second camera and making it a "child" of the original "parent" camera may not get the job done. You have to have independent control over both cameras to do "the great stuff". An alternative to animating the stereo base is to use the "narrowest needed stereo base for one entire segment", in order to avoid excessive overall deviation, but animating the base gives you a much wider range of visual options, especially with all the pans and zooms that you see in a movie like Polar Express. I guess what I am saying is that a simple stereoscopic plugin is not going to do a great job. You might be able to play with it and learn from it, but you really need full independent control over both cameras to do a fantastic job. I think the best solution is to use your "3D animation program of choice" and learn how to do the stereoscopic rendering with it. Sadly, most of the tutorials I have seen are very poor, and none would contain the sorts of things that are required for really good stuff like Polar Express. Those people look like they know what they are doing (except for the lack of horizontal parallax animation ;-) ;-) ;-) P. K. Kid Non-commercial stereoscopic 3D movie clips: (All G-Rated) http://www.puppetkites.net | ||
| marinus lutz Rating: N/A |
Clyde: Shade just creates a second camera, it automates the procedure. As P.K Kid accurately points out, without interocular separation and convergence controls your results won't be great. [And as to what format it saves in, if at all, i haven't the faintest idea, as Shade's tec rep didn't share that much with me]. But still, it's a start. And if you want to get your feet wet in 3D content creation, Shade 7 Standard, at $190 [special sale] is a no-brainer. Cheers, Lutz Skeleton walks into a bar, orders a beer and a mop | ||
| Anonymous Rating: N/A |
Marinus, for those of us on a different part of the planet to wherever you are, is a 'no-brainer' good or bad ? I am honestly not sure :-) | ||
| clyde Rating: N/A |
Hi, Well for a start you can try locating Stereographics' Content creation pack, or teh stereo 3d plugin for 3dmax. (It was free and may still be). This gives you every possible option you would need for creating anag, over/under/ pageflip and interlaced. You can also try Xidmary (cross-eyed Mary) this is free for 3dsmax too. Lightwave has a free stereoplugin as well. Now.. About having independant control over both cameras, Heres where im stumped: afaik... --- the cameras in a stereo production need to emulate a pair of human eyes in every which manner. so.... 1) Convergence is out (although the human eye converges, it belongs to ONE persons viewpoint only. If you try that trick with stereo cameras, sure you can Then "direct the storytelling FOCUS" onto the subject at hand, but consider this... what if I as a viewer *dont* want to see the focus of the subject but instead want to see that fancy building in the background or that hot babe (sexist sexist) in the background walking on the beach... well I will get eyestrain over a period of time due to excessive parallax (fusing the images) on the background. -- Ofcourse --- if you zoom in closeup on the subject or the subject is filling a better part of the frame then its ok to converge. As for more independant control over each camera.. I know Im missing something here but as i think, i would prefer a hundred percent Twin slave versus independant for the following reasons 1) I want both exposures and shutter timings to be the same 2) Both white levels to be the same 3) Both genlocked as close as possible if not perfect 4) single slider base for parallax control 5) No vertical parralax between the 2 cameras (obviously) all these apply to Cgi cams as well .. because in the cgi world too theres "lights" that will play up with un-twinned cameras. Im always learning, so would like to know what I am missing with independant camera control. Regards Clyde | ||
| Puppet Kite Kid Rating: N/A |
Okay, actually the statement, "the cameras in a stereo production need to emulate a pair of human eyes in every which manner" is a misconception. Stereoscopic imagery on a screen or computer is totally different in many ways from the way that we see in reality. We focus on one point in space at a time in reality, and in stereoscopic imagery, we have to present an _entire stereoscopic frame_ (or area) where anyone can look at any one point in space "at will". That is the main difference. A very important thing to do in stereoscopic imagery is to avoid excessive deviation, which is the total amount of parallax from the nearest point to the farthest point in one frame. If you do not do this, there is so much excessive parallax (separation between perspectives) that it is impossible (or highly painful ;-) to focus on everything in the frame. In layman's terms, this would be exactly like walking up way too close to something and trying to focus on everything you have in your sight, including the most distant objects. It is much better to back away a bit and look. We usually actually do this automatically in reality, too. This problem is really common in stereoscopic imagery in "close-ups". The solution is to reduce the stereo base in those conditions. Notice in Polar Express that there were scenes that were extreme "close-ups", but still showed no excessive deviation. This is because they appropriately reduced the stereo base. Since in movies these stereoscopic differences can happen during one pan or zoom, you actually have to animate the stereo base to make it virtually *perfect*. Also, as in Polar Express, it is sometimes a good idea to use a hyper (widened) stereo base for some distant scenes or you won't see any stereoscopic effect at all. You can also do this when a particular scene looks better with a certain amount of stereo depth. Obviously, 3D CGI opens up a lot of possible creativity as far as things like stereo base is concerned, because you can do things that real cameras can't do, like animating the stereo base. Now, you don't have to animate the stereo base throughout the entire movie. My opinion is you should use close to an orthoscopic base (like our eyes) whenever possible, as much as possible, but the problem with stereo base and excessive deviation (or lack of appropriate deviation) usually happens in close-up scenes or distant scenes. We don't have as many options with real cameras. You can only reduce your stereo base to a certain point, unless you have a special "macro" rig. One solution is to stay back away from the subject far enough to avoid excessive deviation. Spreading the cameras apart is an option, too, to create more stereo effect, but there is a practical limit, depending on your gear. Animating the stereo base of a real camera would be virtually impossible, AFAIK, so the solution there is just to avoid excessive deviation by using the "narrowest stereo base needed for one entire segment". We don't usually pan or zoom nearly as much (compared to CGI), so that should be less challenging with real cameras. In addition to stereo base control, I additionally adjust and animate the horizontal alignment in post-production, with a goal of reducing or eliminating ghosting. This is sometimes called "adjusting the stereo window", but a better definition might be "adjusting the horizontal parallax" or just "adjusting the horizontal alignment". It is entirely different from the stereo base adjustments. I have never seen a movie that obviously used ghosting conditions as a goal for doing this, but some movies might have had a horizontal adjustment to change the stereo window for artistic reasons. PKK | ||
| clyde Rating: N/A |
"We focus on one point in space at a time in reality, and in stereoscopic imagery, we have to present an _entire stereoscopic frame_ (or area) where anyone can look at any one point in space "at will". That is the main difference".... errrumm... PKK that's kind of what I said above..  I meant that the cameras should resemble human eyes in everyway and then explained how, even teh convergence bit ;) cheers! Clyde | ||
| Puppet Kite Kid Rating: N/A |
The human eyes don't always look parallel to infinity. Stereoscopic cameras should. The human eyes don't spread apart or move closer together. Stereoscopic cameras should. Also, the resulting stereoscopic imagery should, too. This does not happen in nature. Also, stereoscopic imagery is scaled up or scaled down and displayed on 15 inch monitors and monstrous IMAX screens and everything in between. This does not happen in nature. Etc, etc... the human eyes and stereoscopic cameras and images actually have very little in common, and in fact, if you try to shoot a 3D movie and actually try to emulate a pair of human eyes, you will have a very bad movie with a bunch of stereoscopic image errors that the human eyes will not be able to successfully cope with or adjust to very long without giving you a terrible headache. Your eyes will attempt to adjust to errors, but this is difficult for your eyes to do for any period of time :-). One other thing... with stereoscopic images, the point of depth where your eyes actually focus never changes, i.e., it is _always_ at the screen. In nature, this point changes every time the distance of your point of focus changes. I think the more you learn about stereoscopic imaging and what is required to *perfect* it, the more you realize what a unique environment it has to be, unlike anything that exists anywhere else, including in nature. PKK | ||
| clyde Rating: N/A |
"One other thing... with stereoscopic images, the point of depth where your eyes actually focus never changes, i.e., it is _always_ at the screen. ".. I have to disagree to a certain degree Yes true , both images are being shown on a "flat" surface unlike in real life.. but how do tele-robots and the mars probes and satellites like Ikonos reconstruct full 3d views of structures on earth?.. from stereo views of a scene. (cameras on board these are in effect seeing a flat image of the real world *in* the real world) so basically I could say they are seeing an image of the world on the Flat CCD surface of the camera ....sorta reverse television screen viewing. So with that analogy, if human beings are provided with two views of a scene *EVEN* on a flat surface, We arent "necessarily" only focusing on a flat screen. This is the basis of why our brains are fooled into "BELIEVING" that we are viewing a 3d world in a 3dmovie. Viewing a 3d movie, the brain is constantly sending messages to the eye muscles to shift eye "focus" comprising: Iris close/open, toe-in, and converge instructions. ...its irrelevant to the brain "WHERE" these images are emnating from! IT WANTS to make sense of the 3d info coming to it and "thinks" its real world space that its dealing with, so accordingly instructs the eyes to do the same muscle exercises as it would when taking in real world stereo info. TO put it even more simply after all the rambling above.. have you seen SIRD images.. You have to relax eye focus to an Imaginary point "inside" the monitor screen to "see" the SIRD image. This is what is happening to greatly varying degrees when viewing a stereo movie. There's no denying that the physical distance between the screen and you will never change..but its not the same.. (hard to explain this without a coupla more paragraphs). But I think the term "staring into space" is apt here The only cue you have that its a fake 3d world is because you have 3d glasses on! .. imagine a wall sized Autostereo dispay screen... in the right room ambient lighting it wont be too long into the future when Homecinemas can recreate another world buried inside your living room wall, and Cinematographers shoot movies in true "dimensions" meaning no more giant sized closeups in Gladiator, unless You as the viewer interact with a joystick and decide to "zoom in" on the action. ---ahh buts thats another concept out of the scope of this discussion ...so getting back to how and where we focus in a 3d movie.. its not true that we focus on "the surface of the screen - only" ... this is evident from the fact that badly done stereo video induces headaches.. if we were focussing on the surafce of the screen only there would be no eye muscle fatigue or strain ... ok ok for anaglyph die hards theres teh extra discomfort of chroma murder being commited on your eyes this is because muscles in the eyes are constantly adujusting our "bio cameras" to take in the whole scene and trying to fuse the two seperate images together. Focus as should be defined when discussing 3d stereo views shouldnt be limited to F-stops and lens size and zoom, but should more accurately take in variables like .. convergence, Toe-in (yes eye muscles can toe-in to a very slight degree..) this can be seen, why you go squint when you try to "focus" on your finger tip held 6 incles from your nose.) and final fusing in the brain as well. Now I'll follow up in more detail when I said in previous posts why Stereo cameras should emulate eyes as far as possible.. what I meant was .. they should emulate eyes in every way EXCEPT the toe-in and convergent part. As this would cause headaches if the cameraman/director decided to converge on a subject of interest, meanwhile an end viewer wanted to "focus" on background elements instead. About stereo bases for IMAX etc, where its cool that cameras can be slid horizonatlly for extra parallax .. I have to admit I have'nt done much studying there, so wont comment. But consider this... If I were standing on a ridge at the grand canyon and had the entire vista spread in front of me, would I get a greater feeling of "depth" if my eyes were set wider apart? This line of thought of mine comes from my ongoing work with X3D autostereo displays.. On the 50 inch monitor im working with, the 3D effect goes away if im standing 50feet away from the screen,(standing at 15 feet away tho, is like watching a true 3d Hologram! have u guys seen these displays? things float in mid air around 3 feet in front of the screen)....I cant tell if there's depth anymore over 30 feet, its just a regular 'ole plasma display. So what Im getting at is... "substantial" increase of stereo base is not necessary for big screen productions, and the margin for convergent errors (aka headaches) would be reduced by keeping camera distances the same or just a teeny bit wider that human eyes. This way the Diligent 3D director/cameramen would'nt have to look at every scene to see if "all" elements and subjects in an outdoor scene would be "fusable" by the viewers eyes. ---Movable or animated (in CG) stereo bases is only beneficial on Fast zoom to subject of interest, and if and only if, that subject takes up most of the frame. Ratio of Standard stereo camera : eye spacing, is also the reason why IMAX 3D films offer perfect stereo comfort when viewed on a 15 inch monitor and home theatre screen as is evident from the DVDs. (I dont think they're manually moving the stereo window either for dvd versions). Pshew! Clyde | ||
| clyde Rating: N/A |
hmm.. I re-read the thread again, and now realize what got me launched into the discussion.. Pkk said..."the cameras in a stereo production need to emulate a pair of human eyes in every which manner" is a misconception. Stereoscopic imagery on a screen or computer is totally different in many ways from the way that we see in reality. We focus on one point in space at a time in reality, and in stereoscopic imagery, we have to present an _entire stereoscopic frame_ (or area) where anyone can look at any one point in space "at will". That is the main difference. A very important thing to do in stereoscopic imagery is to avoid excessive deviation, which is the total amount of parallax from the nearest point to the farthest point in one frame. If you do not do this, there is so much excessive parallax (separation between perspectives) that it is impossible (or highly painful ;-) to focus on everything in the frame." But He also said .... "A great stereoscopic plugin would be a monster to create. I hope Polar Express just taught us some great stuff, but I'd still add a thing or two. With 3D CGI, not only do you need to aim your cameras parallel to infinity to create *perfect 3D*, you also have to animate your stereo base (which was done really well in Polar Express). The only additional thing that I'd do after that is animate the horizontal parallax. It would be extremely difficult, if not impossible, to animate both the stereo base and the horizontal parallax at the same time (instant brain freeze ;-). I have done very little CGI, but just creating a second camera and making it a "child" of the original "parent" camera may not get the job done. You have to have independent control over both cameras to do "the great stuff" That's where the contradiction stems from: 1) If you know you want camera aimed parallel (which is what I agree with too) 2) you know that both camras should have same focal length 3)same white balance etc... why then would you want to animate stereo base? and horizontal parallax? This would: 1) create the same "headaches" in fusing background elements in a typical scene. (unless like i keep saying--the subject of interest covers most of the frame) 2) By moving stereo base you introduce potential lighting/shadow errors. meaning wider set cameras would show "hard to fuse in brain" shadows of a subject as the shadows would be offset too much. I get it that you would only increase stereo base for "panorama vista" type scenes, but this would only hold true then for CG movies where *every* element in the world is controllable. even then with the increasing realistic worlds being generated by CG, its virtually impossible to not oversee convergent errors cropping up in your scene for nearby objects, when you expand stereobase. So .. keeping things as close to how human eyes are built is the safest bet.. (yes except a Big NO NO to toed in cameras and on the fly convergence) Ghost of the abyss used on-the fly convergence, but even then, That custom HD cam rig that they used had *Everything" in sync, from color correction, genlock etc etc... or to put it in laymans terms .. fancy controls for each eye ...but in complete sync.. aka.. both working in tandem. ---much the same as having a regular pair of human eyes i's say Cameron did pay attention to how he used on the fly convergence tho, but sparingly but im sure ID find "brain fusing" errors if one *really* looked for them. regards Clyde | ||
| clyde Rating: N/A |
clyde said " That's where the contradiction stems from: 1) If you know you want camera aimed parallel (which is what I agree with too) 2) you know that both camras should have same focal length 3)same white balance etc... why then would you want to animate stereo base? and horizontal parallax? " More importanly I wanted to say ... Why then would you want Independant camera conrtrol?? regards clyde | ||
| Puppet Kite Kid Rating: N/A |
Stereoscopic imaging on a screen produces only "an illusion of real stereoscopic vision". You do actually focus on the screen, only. I am talking about the _actual_ point of depth of focus of the eyes, not focus being defined as "the point of interest". Even when you look "beyond" the screen like you do when trying to find the "hidden image" in a stereogram, or when you converge or diverge your eyes so that each eye "looks" at their respective perspective (yikes! ;-), you actually have to refocus (or stay in focus) with the actual screen depth. Believe it... it is true. Never, never, never, do your eyes _actually_ focus on a point in front of or beyond the screen. BTW, this is one reason why some people have a difficult time "seeing 3D" with stereoscopic imagery on a screen. I thought I explained when it is best to change and/or animate the stereo base and/or the horizontal parallax. I hate to explain that again. Maybe a re-read of what I said would help. I can't think of a good web site, off-hand, that explains this well, but surely there are some good basic pages on www.google.com, especially pertaining to stereo photography. Don't feel alone... this is really difficult stuff to understand, and that is obvious, since there are so many examples of doing it poorly, even at a "professional" level. Again, Polar Express would be a great movie to study. IMO, it stereoscopically pretty much "did all the right things" except animate the horizontal alignment to reduce ghosting for passive stereo or anaglyph viewing. That movie could quite possibly be the best example that we have in the history of 3D movie-making. We should study it closely :-) PKK | ||
| Alatar Rating: N/A |
I think you will find that the vast majority of the experienced filmmakers at Imax -- both in actuality and in CG -- will agree with what you both seem to be agreeing on: - the cameras must always be pointing in perfect parallel - what you are calling "stereo base" (often referred to as "camera interocular" or simply "interocular") is carefully selected for the shot, and, depending on practical limitations, is sometimes dynamically changed (i.e. animated) for dramatic effect. Near the end of Cyberworld there is a shot in which the interocular shifts from 62mm (i.e. lifesized) to several microns over just a few seconds. Note that in CG it is perhaps more helpful to think of reduced interocular as being an increase in the scale of all the whole world (i.e. it's not the interocular shrinking, it's the world growing) and vice-versa. - I have never heard of parallax -- horizontal or vertical -- being deliberated manipulated deliberately in an Imax film with the except of hyperstereo (negative convergence) which is sometimes on backgrounds to enhance the feeling of depth. | ||
| Alatar Rating: N/A |
I should correct that, actually, as I know Noel Archambault did a lot of testing with camera toe-in before he tragically died filming "Galapagos". I believe he may have made some actual use of the technique in "Imagine" (which was all about weird dream sequences anyway, so it would have fit right in). Unfortunately, he is not around anymore to ask, and no-one else I've asked remembers. While trying to find this out though, I did talk to Colin Low, one of the key people in the early development of Imax 3D (and whom I've known for almost 50 years). Before making Transitions, the first Imax 3D film he spent years doing 35mm stereo tests with Ernie McNab and others at the National Film Board of Canada (NFB). He told me a number of interesting details about the use of toe-in in early 3D: - The Ches Beachell stereo camera dating from the early '50s was made from two handheld Eyemo's and had a continuously variable interocular from 2 1/4" to 5 1/2" and had continuously adjustable toe-in - The Russians used toe-in and special optics to eliminate wall-eyeing for their stereo movie at their pavillion in the Osaka world's fair in 1970 (where Imax made it's debut with the 2D "Tiger Child") - The early 35mm tests at the NFB and Transitions did not use toe-in (Colin wanted to try it, but wasn't allowed and/or wasn't able to for schedule reasons) - "We Are Born of Stars" and "Echos of the Sun", the next two 3D Imax films Colin worked as a consultant on also didn't use toe-in at all. The next time I am talking to Graeme or Toni I will ask them about "Into the Deep". | ||
| Alatar Rating: N/A |
This one has obviously become a bee in my bonnet as it has driven me to call Graeme Ferguson (co-founder of Imax and a key player in much of Imax's 3D work) who informs me that there is no toe-in used "Into the Deep". He also gave me a lot more very interesting information on the subject, including the strategies being used in the current filming of "Denizens of the Deep". Unfortunately, I am obliged to check with the relevant Imax people before posting any of it here. I will post more if and when I am given the green light to do so. | ||
| Puppet Kite Kid Rating: N/A |
Okay, toe-in creates keystone distortion, which is a definite "no-no", IMO, but some 3D movie-makers probably use it to avoid having to make horizontal parallax adjustments in post production or to shoot close-up subjects. Bad choice, IMO, as most stereo photographers will also tell you. Simply put, horizontal parallax adjustments in post production (not stereo base adjustments) would enable you to set the point of zero parallax and the amount of positive parallax ("beyond the screen" effect) and negative parallax ("in front of the screen" effect, i.e., "comin' at ya" effect), where things appear to come out over the audience's head. This is sometimes referred to as "setting the stereo window" and I've used that term too, but some people's opinion is the "stereo window" is not really definable if you can't clearly see the edges of the screen, as with some large movie screens, so I am trying to avoid that terminology in this context. Also, you can have another variable, and that is "on-screen parallax" which can be changed on site by independently moving the projected left and/or right perspective images left or right (horizontal). This is *different* than making horizontal adjustments to the film or video itself, although it produces similar results. Obviously, it is impossible to accurately animate the horizontal parallax by moving the projectors, so animation of the horizontal parallax should be done in post production to the video or film itself. As I said, I personally animate the horizontal parallax "in post" to reduce or eliminate ghosting, and I just let the amount of positive and negative parallax "fall where it may". If excessive positive parallax exists, potentially creating a condition where the audience would have to diverge their eyes to an "unacceptable" level, I personally would try my best to decrease the stereo base, rather than adjust the horizontal alignment to a point where it creates ghosting. This is never affected by stereo base adjustments. Stereo base adjustments only affect the "amount" of parallax, not the "placement" of it. PKK | ||
| Clyde Rating: N/A |
Thanks Pkk and Alatar (an email address would help us alatar, u seem very knowledgeable on many aspects of 3d) I will take in many of the points and concepts pointed out by Pkk, there's obviously stuff worth investigating in what he's saying (I'm always learning) Still Im doing my own limited research into eye fatigue, good stereo viewer comfort and evangelising the cause of better chromatically accurate anaglyph filters, until strain free autostereo makes a serious inroad Cheers all Clyde | ||
| Alatar Rating: N/A |
Ok, I have got a go-ahead to talk about some of the stuff I was told about last week. Firstly, Imax's view is to *almost* never use any toe-in with one or two carefully controlled exceptions. However, some (maybe most) Imax 3D cameras support this capability -- not by actually toe-ing in which, as PKK rightly points out, causes keystoning, but by shifting the lens relative to the film gate and thus avoiding keystoning. Obviously proper account has to be taken of the background (to prevent wall-eyeing) using soft focus, blue-screening or some other technique. In fact, these days, Imax's policy these days is to provide equipment capable of doing it, and leaving it up to the director to decide. Although I was correct in stating that none of the early Imax 3D films used the technique, several recent ones have used it in very specific places. Clyde - I've sent you an email with my coordinates. | ||
| Alatar Rating: N/A |
PKK, the difference in where we are coming from is that in "ad-hoc" or even permanent one-off installations it is possible to adjust the displacement of the two projector images relative to each other. Imax theaters don't have this luxury as every stereo movie has to play in every theater right off the bat and without adjustment. So there has to be a standard that all the theaters follow and all the directors work towards. There is no option to adjust anything after the prints are made. You and I have had this discussion before and didn't finally resolve it -- you had to leave for Japan, I believe -- but one missing part I wasn't able to explain then (but now can) is this: All Imax theaters have the projectors aligned to project exactly one (average) human interocular apart on the screen plane. This means that a single dot at exactly the same point on both prints will *always* appear at infinity to the audience. In cases where the dot on the right-eye print is further to the left than other, it will appear closer than infinity. No object or point will *ever* *ever* appear further to the right on the right-eye print. The other half of this standard is that the optimum audience field of view in all Imax theaters is kept constant. So it doesn't matter how big the theater is (i.e. how far away the screen is), the pyramid beginning at the right eye and ending at the screen corners never moves, it just scales, and scales perfectly with the image size. And thus every Imax viewer (at least every viewer in the optimum seat) always sees exactly the same picture geometry, regardless of theater size. Imax has always strived to have the very highest presentation quality possible, and they are generally very successful. The standardized approach described above is one of several key design decisions made to achieve this goal. | ||
| Puppet Kite Kid Rating: N/A |
Bummer. Setting every movie up to be projected "at infinity" seems like overkill, but that's one way to avoid audience eye divergence ;-) If you don't have a viewing environment that is capable of perfect cancellation in the glasses, you are going to get a lot of ghosting! To stop or highly reduce ghosting by editing the movie itself, the way I do it, you'd have to depend on a "maximum amount of _acceptable_ positive parallax" (2 degrees?... 3 degrees?) to be present in the viewing environment in order to be able to adjust and animate the horizontal alignment of the movie itself, which would be preserved on the prints or any "copy" of the movie. To preserve those resulting adjustments, you would always have to align the on-screen projections to "the same point". In this case, the IMAX setup would work as it is. I was counting on using a smaller stereo base to reduce the overall deviation, but I would have to do the math to figure out what the "maximum amount of acceptable positive parallax" would be on the *largest* screen. Any screen smaller than that, then, would be considered "safe". The problem is some IMAX screens might simply be "too big", but also, I have heard some stereoscopic experts say that "sometimes excessive positive parallax is just a way of life with stereoscopy", i.e., sometimes it is impossible to eliminate it. I guess you can also use some people's opinion about toe-in as an excuse, here, which can also create serious excessive deviation in distant objects, that "people are looking at the subject, not the background". Yikes... that comment sure makes the hair on many people's heads stand straight up ;-) PKK | ||
| Puppet Kite Kid Rating: N/A |
I wrote: "...you'd have to depend on a "maximum amount of _acceptable_ positive parallax" (2 degrees?... 3 degrees?) to be present in the viewing environment in order to be able to adjust and animate the horizontal alignment of the movie itself." That was an error. I meant that you would have to depend on a "tolerance of it" on some screens. It would only "be present" when a screen size gets to a certain size, and over. PKK | ||
| Puppet Kite Kid Rating: N/A |
I just did some quick research on the topic of eye divergence during projection, and there is quite a bit of information available via the internet. Obviously, this is a common debate, especially when it comes to IMAX movies. As far as adjusting the movie's horizontal parallax (the movie, itself, not the projectors) to reduce or eliminate ghosting is concerned, using my method, the only real solutions I can see for large screens is to either (1) output a separate version of the final edit for "large screens" that shifts the entire movie (with adjustments intact) to avoid "excessive" eye divergence (whatever that might be defined as... 1.5 degree maximum or whatever) or (2) rely on projector adjustments. I still don't think I would ever use "no positive parallax", though... even an "acceptable 1.5 degree" divergence factor would reduce the "relative thickness" of any resulting ghosting caused by the on-screen placement of my movies, and that does help a lot. The great thing about doing the adjustments to the movie itself, like I do, is you do eliminate or highly reduce ghosting on all *smaller* screens, and that includes most of the environments that most of us use to view 3D movies (computer, home projection, etc). The only challenging thing is avoiding eye divergence on *large* screens, but surely this is a better solution than just using "zero positive parallax" for all environments. This is one of the most common complaints about IMAX movies on DVD, for example. My method not only solves that problem, but it potentially highly reduces or eliminates ghosting. The only possible negative by-product of my method is window violations, but I use a thin blurred border to reduce that effect. It looks to me like IMAX theaters should always provide on-screen projection adjustments, no matter how they have to get the job done. I don't think in practice that they have ever been able to rely on parallax adjustments made to the movie's themselves, anyway... according to the many reports I have heard or read. PKK |
