More Thoughts On 3D Cinema Optics

May 7th, 2009 by Clint

I don’t have the same pessimism for 3D in the long run as the article that David Newman was responding to with his “No Problem With 3-D”. I have the strong sense that humans are clever creatures, and we will find ways to fix most of the problems that bother us. However, I don’t think we have the technical aspects of 3D mastered. We don’t get nauseous from 3D effects while watching a play on stage, even when Gallagher smashes a watermelon in our face, so I think there is still something afoot.

I can’t yet dismiss the idea that seeking between objects with unmatched convergence and focal properties is a way to cause viewer discomfort, even though David is pretty convincing that we won’t suffer long-term damage. Since the convergence point of the stereo pair should track with the object distance (as David Stripinis has pointed out), doesn’t that limit us to a single plane of interest where the convergence point and focus coincide? That would mean that a close-up large object would have one area that hits the sweet spot, and maybe the further from that area that your eye travels, the more confused you will be.

To revisit a point I touched in “Where Have 3D Stereoscopic Movies Taken You?”, John Batter once discussed how it’s important to carefully pace the amount of depth effect. Poorly paced depth effects lead to increased fatigue, which could also be a nausea contributor.

I’m starting to think that hyperfocal areas don’t work the same with stereo pairs as they do with a single lens (like in David’s optics examples), because the perceived image includes ghosting from opposite eye images. For near objects, I suspect this ghosting dramatically decreases the effective focal depth of a pair of eyes. Maybe this is part of why deep focus establishing 3D shots are my favorite. The amount of blur in areas surrounding objects of interest provide a strong cue as to the expected seek distance to move focus to another object. The camera lenses bake in a single blur amount for the scene, but in real life, the amount of blur changes based on the location of the object of interest with relation to the other objects. I wonder if there is enough of a mismatch between the expected seek distance and actual seek distance to cause a feeling that the world is shifting around unnaturally.

Ordinarily, we shift our heads slightly to “fix” confusing or interfering occlusion and edge problems, but it’s impossible to have a head shift fix anything for projected film. Shifts in object occlusion in real life depend mostly on distance from viewer. If we happen to flinch out of the way of a near-field object flying at us, the projected image won’t shift at all, leading to a definite mismatch between expected and observed motion. This kind of mismatch is what causes seasickness according to my favorite explanation in Alton Brown’s Good Eat’s episode, Rise of the Rhizome (starting at 6:55).

This does hint at another reason for why I love deep-focus establishing shots. Maybe there is only a tiny amount of parallax shift expected for far off objects when I shift my position around, so the lack of shift on the screen isn’t unsettling.

One trick to detect stereoscopic problems would be to track the head movements of a test audience. The more movement for a scene, the more likely it is to be nausea inducing. This might also be related to the classic “audience engagement” metric, where the times when the audience shifts in unison are worthy of extra attention.

I think we should create a 3D film nausea index combining the amount of seeking required between cuts, the magnitude of mismatch between expected and actual seek distance from object to object in a shot, and the ratio of in-focus objects that don’t have matched focal and stereo convergence properties. Once we can quantify the factors that contribute to viewer discomfort, we can automatically warn the editor and maybe someday the director on set, when they’re pushing the limits.

I’m still eagerly awaiting the first 3D gag that breaks the widescreen matte for added effect, even if there is still some discomfort caused by the medium. While I hope 3D can help filmmakers connect with the audience better, all I really want is to be shown another great story.

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Where Have 3D Stereoscopic Movies Taken You?

February 26th, 2009 by Clint

I can comfortably say that the range of quality of 3D cinema is almost as wide as the range of 2D cinema. Story and celebrity are still king. The introduction of digital 3D cinema seems to be an evolution more like the transition from 2 channel audio to 5 channel audio than the revolutions of sound and color.

The added dimension gives a better sense of scale. It provides another positional queue that can be used to manipulate the viewer’s immersion. Whether two or three dimensions per frame, films are still the filmmaker’s framing of the world through the window of the camera lens.

Technology Can’t Save A Bad Story

I saw a demo of Alioscopy’s auto-stereoscopic (no glasses needed) 3D display, which is a fancy plastic lens on top of an LCD. It actually works, but has a limited number of viewing angles, and requires an array of 8-10 cameras to create the video. I think this necessarily means the effective resolution is one-eighth to one-tenth of the LCD’s native capability.

I also saw a demo of 3D capabilities being built into some new LCD TVs at incredibly low cost. This wonderfully brings 3D into the home, and is claimed to be compatible with Sony’s high-def players. Neither of these techniques are practical for a theater though.

Turtles All The Way Down

The most popular projection technique for 3D is circular polarization, which maintains left/right channel separation extremely well, and is more robust at preserving color levels than linear polarization. The polarization is accomplished with a filter (linear polarizer mated with a magnetic field generator called a retardation plate) in front of the projector. The polarizer, which makes light coherent so the 3D trick works, is the death of brightness, killing over half (~60%) of the projector’s light. The light that gets through is spun clockwise or counter-clockwise depending on the electric field (+ to -, or – to +), which is switching at 144fps, or 6 times per frame. And then he 3D glasses take another 10% of the light. This is all fascinating to be sure, but if you’re switching a single image 6 times per frame to reverse the polarization, you’ve introduced 6 blanking periods.

Blanking periods are fine if they’re part of the media (like in a film projector), but when they’re introduced this way, you get unnatural motion that ghosts and stutters. This is noticeable (and distracting) in any scene with moderate motion – I bet snail documentaries look excellent. One published spec put the filter’s transition time in the blanking period at a very impressive .6ms, which means 3.6ms per frame, or 8.63% blackness as a conservative estimate, but I’d guess it’s closer to 15% in the end. A 2-projector setup isn’t unreasonable to help fix this, and maybe a 6-chip projector will work, but collimating light is a bitch.

A giant LED jumbotron will be even better if we can get consistent color. To make the 3D gag work, each pixel on the screen gets a clockwise or counter-clockwise polarizing filter. If you want to cling to the 4k wagon, then you’ll want an 8k display, but that seems excessive. “Modern” theaters are purpose-built facilities anyway, so why not ditch the silver screen?

“Because I Can” Isn’t Good Enough

3D has hit its stride is with computer-generated films, portraying a synthetic world through synthetic cameras. At The Conversation in Berkeley last year, DreamWorks’s John Batter showed us the Tai Lung escape scene from Kung Fu Panda, specially re-worked for 3D. It was great. John also said they carefully paced the depth effects because it easily becomes tiring, and scene transitions are carefully managed to prevent nausea. One of the more entertaining things I learned from him is that audiences don’t like to get poked, like with the pick-axe-in-the-eye gag that kicks off My Bloody Valentine. With that movie, the break of immersion caused by 3D gags was welcome, and maybe that wasn’t entirely accidental. An oddity worth remarking was the Superman “put on glasses now” scenes that were in 3D – bad idea.

One potential playground for 3D is aspect ratio games. Like the The Dark Knight IMAX (and a handful of other predecessors like More American Graffitti), we’re sure to see 2.35:1 frames being broken for added effect, because the mastering is really 16×9 (caveat projectionist).

The best use of 3D I’ve seen yet was in the awkwardly live BCS championship game. The 3D motion stutter is terrible for watching football, but you can easily grasp the relative sizes of the players in the huddle. One eye of the projection would regularly go haywire, followed by a full audience groan. One shot sang to me every time they used it: a deep-focus establishing shot all the way across the field from a corner of the end zone. The camera played the perfect role, melting away, leaving me wondering why I couldn’t smell the dirt on the field.

I Can Make A Plasticine Pancake

3D isn’t working for me in the claymation realm either. For Nightmare Before Christmas, 3D was added synthetically, and never felt like anything more than 2D cards floating around. With Coraline, the preview was nauseating because of the scene transitions, which luckily wasn’t a problem with the film. Deep-focus shots were again the most powerful, but most of the time the motion stutter was more distracting to me than the 3D was immersive.

Fix It In Post

Seam carving paired with re-projection is a candidate for making live action 3D as workable as computer-generated 3D is. Seam carving is a daunting task in two dimensions, but for many scenes, having stereoscopic pairs will help resolve features. You then rearrange the elements in 3D space, which brings you into the computer-generated arena, where a synthetic world and a synthetic camera are the ultimate in flexibility. The drawbacks to this approach include needing to capture at higher resolutions, and needing lots of light because you want to be stopping down your lens, aiming for the deepest focus possible. The more in focus the entire scene is, the more flexibility you have to adjust the virtual lenses during re-projection.

I Miss Captain EO

So far, story has been secondary to the technology with 3D films. This is almost predictable though, since the technical barriers to 3D are significant. Not only must filmmakers be fluent in the language of film, but they also need to blaze the trail in 3D production, inventing norms as they go. So far, only equipment manufacturers have seriously benefited. If anyone can make use of the immersive potential of 3D, it’s the likes of Steven Spielberg, James Cameron, and George Lucas, with brilliant crews and infinite resources to help tackle their problems. I can’t wait for the great storytellers to tell me another story. If they want to tell it to me in 3D, then so be it, but I don’t think it’s necessary.

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Dell Frame of Reference Winner!

September 12th, 2008 by Clint

On Sunday August 31, at the 35th Telluride Film Festival, really early in the morning, we were announced as the winners of the Dell Frame of Reference competition for our short film Prohibition 2020, starring three friends from work, Nick Heredia, Christine Hara, and Kyle Phew.

As one of three finalists, I was tasked with creating a ten to twenty minute short film. This project was the longest and most complicated that we’ve attempted. Selected by a panel of judges as the winner, our entry screened at the Dell Lounge in the Brigadoon tent during a special breakfast awards ceremony. The competition called for a film in the style of French New Wave, with an “Out of My League” theme, featuring the song They’re Outnumbered by Dignan.



Prohibition 2020 takes place in the not-too-distant future in San Francisco, where strict prohibition laws are being enforced. David’s hobby is making moonshine whiskey in his garage, and he meets a well-connected wine dealer that he wants to impress.

The entire project was done in about seven weeks. The first two weeks after getting the contest requirements were spent watching and learning about French New Wave films (the commentary track on Breathless is magnificent). Script planning took a week or so, and most of the principal photography was done in a weekend. A week-long vacation to Portland gave me a break in the middle. Finally, editing and filling in the gaps took every bit of free time and every ounce of energy I had for the last three weeks. More behind-the-scenes action will be available soon.

The other entries are both impressively well made, and definitely worth watching. From what we heard, our use of French New Wave elements is what set us apart.

Read more about Prohibition 2020

Huge thanks again to everyone who helped out, and to everyone who encouraged us along the way!

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The New Cook’s Almanac Is A Prize Winning Short

June 18th, 2008 by Clint

The Filmmaking Frenzy folks sent a newsletter on March 24th which mentioned Dell Lounge was hosting the Frame Of Reference themed contest, submissions due April 4th. Entrants mix-and-match style, theme, and song into a short up to five minutes long. Writing and planning for The New Cook’s Almanac was done by the weekend, when Matt and I went to Nick’s house to film in his kitchen. The entire project was finished in about 9 days.

Read more about The New Cook’s Almanac

After three rounds of voting and judging, we became one of three finalist groups eligible for the grand prize, which will be awarded for the best micro-budget twenty minute short produced before the August deadline. We’ve won money, a computer, and a trip to the Telluride Film Festival. Each team will also track its progress somewhere on the Dell Lounge website.

Marisa’s cooking show concept came from her deep appreciation for food and cooking shows like Good Eats and No Reservations. I had the script by Thursday, and spent evenings shopping for props. On Saturday Matt hot-glued fishing line to mini-squash while Nick and I injected food coloring into eggs. Finally, we had to negotiate with the Union of Flying Saucer Operators to get the heat ray to show up on schedule.

Editing took all the way to the deadline. The music was my piano version of the competition song. I can’t play piano, so it’s really a franken-recording of a few notes at a time, all glued together. Since it was so close to the deadline, the drum pad accompaniment was recorded in a single ad-lib take.

Enormous thanks to everyone involved, but you’re not off the hook yet. Our next short film is due August 20th!

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The CIFF 2008 Iron Filmmaker Winner

May 1st, 2008 by Clint

The CIFF 2008 Iron Filmmaker Winner – Wasn’t Us!

In Livermore on April 17th, we entered the California Independent Film Festival’s 24-hour Iron Filmmaker competition. The TV show Iron Chef is the competition’s namesake. In Iron Chef a secret ingredient is revealed, and cooks compete to see who can make better culinary creations with the ingredient. In Iron Filmmaker the secret ingredients are things that need to be in contestant’s film creations.

I suspect there wasn’t enough communication between the sponsor and the festival representatives. Instead of a themed competition, we were told to make a Carl’s Jr. commercial. The sponsor didn’t make the proper connection to Iron Chef, and in the printed rules they even called the event the “Ironman Film Contest”. The prizes were great for encouraging first-time filmmakers, but were at least an order of magnitude less than usual for an advertisement competition. The Contra Costa Times covered the kick-off (EDIT: but since put the article behind a pay-wall).

I wanted to make a film, I wanted to be creative in the spirit of the competition, and I wanted to make it impossible to use our work as a promotion. I feel sorry for the people who paid to watch – under normal circumstances they would’ve been paid for being in the focus group and watching commercial after commercial.

We got the biggest laughs, and the biggest applause, and somehow didn’t place in the top three. There was a scary moment when they stopped the film after the first segment and had to re-start it. The momentum was lost, but it didn’t really matter in the end.

After work, Aaron went grocery shopping while I drove Nick around town to gather footage before sunset. We filmed in Aaron’s kitchen and wrapped up within a couple hours. Marisa kept me caffeinated while I edited all night long. I made it out the door just in time for the traffic jam on the freeway. The back-roads were slow, but I made the submission deadline.

Thanks again to everyone who helped out. I had a great time in spite of the flawed premise, and am proud of what we accomplished.

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