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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Stereo 3D Fundamentals (RealD iOS app)

Brian Rocafort

Brian Rocafort

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I am still new to this, but we recently received an Element Technica quasar rig in Beijing. We took Element Technica's training course with the Quasar a couple months ago and I currently feel quite comfortable building, aligning & operating the rig. I have read a ton of articles on stereo theory but I still don't feel comfortable functioning at a stereographer. The scary thing is I have spoke and worked with a few local stereographers, who certainly are confident, but clearly have no idea what they are doing. (Test shots have shown up with tons of excessive parallax. Their concept of IA seems to be more of a guessing game than a science. Ie: in an interview setup, shooting a static, dead on with a 24mm lens 30ft away from the furthest object, converged on a subject 10ft from the camera, the IA will jump back and fourth from 120mm - 20mm within the same shot.) I hope that all makes sense.

Anyway we finally have an opportunity to get our hands on a pair of RED ones over the weekend and do some test shoots. Last week I bought the RealD iPad app and intend on using that as a starting point. Here is my question: Once all of your parameters are set in the app, my understanding is that objects (at least in theory) should not diverge more than 2% into negative (-2%) or positive (2%) parallax from the screen plane? Also would I be completely wrong to call the "screen plane" the converged point? The numbers seem to coincide, at least within the realms of the RealD app, but I am slightly scared to make any assumptions.

Once again I hope everything I wrote makes sense. I am still very new to this. Needless to say any sort of insight would be greatly appreciated.
 
Hi Brian,

Things will click into place with experience, but you won't really get your head round the theory until you're actually doing it and having to make the decisions for yourself. 'Stereographer' is just a title - it's often a bit mis-used though as it can cover a plethora of different skillsets. In my opinion, it's about being confident that you have the knowledge to assess and deal with any shot that is thrown at you. It also involves much much more than what you do on-set! It's about using that knowledge to advise (potential) clients what works well and what doesn't in 3D, how to approach a shoot/shot to get the most out of it, what kit they should use etc. All whilst doing your best to ensure that the film/short (read: story) comes first. It can also carry on into Post, helping to advise on best workflows and ensuring that the Post house actually know what they are doing (a lot don't). Don't worry about others - they'll get found out!

Apps are useful for pre-viz or determining what rigs you'll need in specific positions but they are little use on-set. The crucial thing is to make sure that you have decent monitoring, whether that be a professional 3D monitor (Transvideo, JVC, Panasonic etc) or using a StereoBrain (disclaimer: we developed this) onto a standard HD-SDI monitor or 3DTV. Then you can be sure that you're getting it right - no app is going to be more reliable than your eyes. If you don't have a proper 3D monitor, you can use the StereoBrain to output Anaglyph or Difference matte onto a standard 2D monitor. There are a thousand ways in which you can slip up with Stereo, but provided you're conscientious you should be ok.

Anaglyph works really well for monitoring as parallax shows up on-screen as coloured areas. The most simple way to make sure you're working within acceptable limits (usually around 2% positive or in-to-screen parallax, 1% negative or out-of-screen parallax for TV) is to measure the width of the picture on your monitor and divide that by 1% or 2% and stick on some gaffer tape with markings on it. This will help to remind you what 1% or 2% looks like (the professional monitors will allow you to overlay these guides). Then turn up the IA, converge on your subject and adjust the IA until the background parallax doesn't exceed 2%. There's obviously more to it than that, but you should at least come away with some usable footage at least! You definitely shouldn't end up with the sort of extreme parallax you've mentioned.

In terms of choosing your convergence point, as a very general rule this is your subject or somewhere about 1/3 way up the image. Obviously, this will vary hugely dependent on your scene but, as a general rule, this should work. Don't feel like you need to have stuff coming out-of-screen all the time.

The main thing is you have a great rig to be learning on, so you should have to do relatively little in terms of alignment once you've set it up initially.

TOP TIP: Use an Ambient Lockit ACL203 (if you have one available) rather than an AJA Gen10 to provide sync to the RED Ones - I've found them to be far more reliable. You'll need a BNC splitter (T adaptor) for the Lockit...

Good luck and enjoy! Let us know how you get on...

Regards

Campbell
 
Although this may be the first time I am publicly stating this, I am fairly confident that I coined the term "stereographer". As many of you may know, I have been in this field of over 18 years and started calling myself a stereographer about 10 years ago at a time when other 3D practitioners considered themselves 3D consultants, directors of 3D photographer or other things. It is hard to verify a statement like this so rather than boasting, I'm putting it out there because I would like to confirm or possibly have someone point out that I am incorrect. For sure, I am the first person in Hollywood history to recieve a screen credit as "Stereographer" in a theatrically released feature film. I know this because the DGA fought us tooth and nail to not allow it at first based on the fact that "no such title exists" according to them at the time.

That aside, I think it does give me some authority to weigh in on what the definition of the term is. Just like a photographer makes a photograph, a stereographer makes a stereo image. This is a broad definition but that's essentially it. With that being said, if you snap a photo with your cell phone and give it to someone, they might ask "hey, who was the photographer who took this..." regardless of the quality or medium, the person who took the picture is the photographer. Point being, just because someone says they are a stererographer doesn't mean they are any good or have studied the discipline at all.

Furthermore, I am finding that even after 18 years, on almost every single shoot I do, I am refining my process, honing my skills and learning new things all the time. This is one of those pursuits where, while obviously some will have an immediate knack for it and others will not, there is no substitute for the hard learned lessons of EXPERIENCE.

The percentages you've discussed are a potential starting point although I've read from some on the CML that they feel 2% to be too much parallax. I will not agree or disagree with this. There is no hard and fast rule that applies to every lens, every composition, every shooting situation. But setting boundaries is smart particularly for beginners and a good way to keep yourself out of trouble. Get a Transvideo monitor or something similar that can overlay a grid on your image and use that to ensure you stay within your own guidelines.

Be aware however, that despite people's tendency lately to not want to do this, there is significantly greater allowance for negative parallax (things coming off screen) than there is for positive parallax. The reason for this is simple. Our eye can cross quite easily and do all the time. If you look at your watch to see what time it, or your cell phone to read a text, your eyes are converging on a subject inches from your face. If you observe another person doing this, you can see their eyes physically crossed. Conversely, when you look at something off in the distance, your eyes just will not rotate outward beyond parallel. Keep this in mind when shooting, but do lots of tests and get as much audience feedback as you can.

My final bit of advice is to beware of anyone claiming to be a stereographer with limited or dubious credits and demand to see a demo reel before you hire them.
 
Hi Brian, it's all about practice practice practice.

Have you tried our app IOD Calc Jr.... it's free and will get you perfect 3D if set up correctly and you follow its advice.

http://itunes.apple.com/au/app/iod-calc-jnr/id406911180?mt=8

I agree with Jason, there are very few people who are truly capable with making good stereo, very few. I always wondered why there were no Stereographers on older 3D shows like Capt.EO, I just assumed that no one wanted to take credit for the horrible stereo.
 
I saw Captain EO as a young boy and enjoyed it immensely. I definitely count that film as one of my early inspirations and will not criticize the stereo for that reason and also because I have not seen it in probalby 25 years or more. I will admit to having seen 3D films that I loved as a child and upon more recent screenings recognize major technical flaws, but I will give those productions the benefit of the doubt in as much as the technology was far less sophisticated then.

Peter Anderson was the stereo guru on Captain EO and I will also not criticize Peter. This is a good example of someone who, by all measures, is a stereographer for sure but was probably credited as Director of 3D Photography or something like that. Even on U23D (Peter's most recent work to my knowledge) he is credited as Cinematographer and Visual Effects Supervisor, although it is well known that he was the lead stereographer on the film.
 
Hey Brian, glad to hear you are going to be on one of our rigs. If you hit any snags, please let us know!

As far as stereographers, well, the title itself has become just way too vague and unregulated. It turns out you don't have to prove yourself to give yourself the title of "Stereographer". As it turns out, something as simple as attending Sony's 3D course is all you need to throw that title onto a business card. Then there are conversion (2D-3D) Stereographers which I feel should be distinguished between practical Stereographers who actually "shoot 3D".

As far as the 2% issue, this is where being a good Stereographer comes in. Knowing when its ok to break that rule. Because there are occasions.

And as those that have responded have mentioned, PRACTICE! You would be amazed at what just two days of test shooting will net you.
 
Hi Brian,

hope I'm not sounding rude but it seams like you need a little bit more solid ground on stereoscopy. I would recommend you buying the "3D moviemaking" book : http://www.amazon.com/3D-Movie-Making-Stereoscopic-Digital/dp/0240811372

and this interactive course: http://www.convergence3d.net/stereo3d.php

I own them both and they both are great.

I'm trying to gather a few free white papers that I've downloaded over the years, when I get everything together I'll be posting them here on a new thread (mostly are in Spanish/Portuguese though).
 
never diverge

never diverge

Brian Rocafort said:
should not diverge more than 2% into negative (-2%) or positive (2%) parallax from the screen plane?
Click to expand...

It is un-natural for peoples eyes to diverge, you should never shoot or release for that to happen.

You should make sure that subjects at INF are aligned in the images shown, not "behind the screen" because if the movie is watched on a small screen later the amount of spacing of the two images on the screen in ratio to the actual screen width will vary with screen size, and so the divergence will vary with the viewing distance.

The cameras should be parallel for the most part. If there is a wall behind the subject you can align the cameras on that as the most distant part of the image possable.

You need to think about the spacing of image points as they very with viewing screen size, the maximum spacing would be about 62.5mm for ALL screen sizes in order not to diverge, but in a movie theatre 62.5mm is almost the same as aligned, on a small home screen 62.5mm would be a much larger part of the screen width. So is is best to not have anything shown behind the screen plane. If you keep the most distant point aligned in the images shown, then it does not matter what size screen the images are shown on, or the distance of the viewer as eyes can converge on close objects and people will move back instinctively, or you limit the camera to subject distance normally so that close issue is not a problem.

The cameras should be close enough together that foreground does not cause excess parallax, and subject matter should not be too close to the cameras but that minimum distance varies with the focal length used.

For nature and sports tele shots you might use a parallel spacing of 200mm but nothing could be closer than 60 feet.

For wide angle close up shots with the subject between 1 and 2 feet away you would need to reduce the spacing to about 1/4 normal (and keep the cameras parallel) because the close distance for 62.5mm spacing with "normal" lenses would be about 6 to 8 feet away from the camera.

Divergence can be painfull and cause eyes to water and if filmmakers keep doing it it will reduce the success of 3D cinematography. Just say no to divergence of the viewers eyes.
 
Great advice from everyone.

I think I own ALL the calculators for iPhone, 5 of them at the moment.

They are all good for different things but my first call is the RealD one followed by the French Stereographer one.

FrameForge is a great way to learn about 3D and I recommend to everyone that they try it.

Of course there's always my 3D survival guide http://itunes.apple.com/us/book/3d-cinematography-basics/id432279161?ls=1 which is an attempt to give camera crews a very basic understanding of IA and convergence and all the basics.

The numbers are useful but keep looking at what you get because sometime the numbers don't make sense.
 
Thanks for all of the info Campbell. I really appreciate it. Funny enough we caught on early and replaced our Gen10 with the Ambient Lockit ACL203. We did a fair bit of research before purchasing the rig and that seemed to be a common issue with the RED one. The ACL203 has been great.

Campbell Goodwille said:
Hi Brian,

Things will click into place with experience, but you won't really get your head round the theory until you're actually doing it and having to make the decisions for yourself. 'Stereographer' is just a title - it's often a bit mis-used though as it can cover a plethora of different skillsets. In my opinion, it's about being confident that you have the knowledge to assess and deal with any shot that is thrown at you. It also involves much much more than what you do on-set! It's about using that knowledge to advise (potential) clients what works well and what doesn't in 3D, how to approach a shoot/shot to get the most out of it, what kit they should use etc. All whilst doing your best to ensure that the film/short (read: story) comes first. It can also carry on into Post, helping to advise on best workflows and ensuring that the Post house actually know what they are doing (a lot don't). Don't worry about others - they'll get found out!

Apps are useful for pre-viz or determining what rigs you'll need in specific positions but they are little use on-set. The crucial thing is to make sure that you have decent monitoring, whether that be a professional 3D monitor (Transvideo, JVC, Panasonic etc) or using a StereoBrain (disclaimer: we developed this) onto a standard HD-SDI monitor or 3DTV. Then you can be sure that you're getting it right - no app is going to be more reliable than your eyes. If you don't have a proper 3D monitor, you can use the StereoBrain to output Anaglyph or Difference matte onto a standard 2D monitor. There are a thousand ways in which you can slip up with Stereo, but provided you're conscientious you should be ok.

Anaglyph works really well for monitoring as parallax shows up on-screen as coloured areas. The most simple way to make sure you're working within acceptable limits (usually around 2% positive or in-to-screen parallax, 1% negative or out-of-screen parallax for TV) is to measure the width of the picture on your monitor and divide that by 1% or 2% and stick on some gaffer tape with markings on it. This will help to remind you what 1% or 2% looks like (the professional monitors will allow you to overlay these guides). Then turn up the IA, converge on your subject and adjust the IA until the background parallax doesn't exceed 2%. There's obviously more to it than that, but you should at least come away with some usable footage at least! You definitely shouldn't end up with the sort of extreme parallax you've mentioned.

In terms of choosing your convergence point, as a very general rule this is your subject or somewhere about 1/3 way up the image. Obviously, this will vary hugely dependent on your scene but, as a general rule, this should work. Don't feel like you need to have stuff coming out-of-screen all the time.

The main thing is you have a great rig to be learning on, so you should have to do relatively little in terms of alignment once you've set it up initially.

TOP TIP: Use an Ambient Lockit ACL203 (if you have one available) rather than an AJA Gen10 to provide sync to the RED Ones - I've found them to be far more reliable. You'll need a BNC splitter (T adaptor) for the Lockit...

Good luck and enjoy! Let us know how you get on...

Regards

Campbell
Click to expand...
 
Thanks Aaron. I just downloaded your app. Looks great. Been hearing some really good things about the new rigs E3D have been working on. I am anxious to see them in action.

Aaron McLane said:
Hi Brian, it's all about practice practice practice.

Have you tried our app IOD Calc Jr.... it's free and will get you perfect 3D if set up correctly and you follow its advice.

http://itunes.apple.com/au/app/iod-calc-jnr/id406911180?mt=8

I agree with Jason, there are very few people who are truly capable with making good stereo, very few. I always wondered why there were no Stereographers on older 3D shows like Capt.EO, I just assumed that no one wanted to take credit for the horrible stereo.
Click to expand...
 
Thanks for the support Joey. So far so good. Quick question. What size are the allen key set screws that correspond with the hard stops underneath the Quasar motor box? luckily they weren't in very tight when the rig shipped. I was able to carefully loosen them with a flathead. I wouldn't want to use this as a permanent solution and risk damaging the screws when locking/unlocking our hard stops in the future. I believe our bondhus allen key sets are standard sizes. Are the hard stop screws metric?

Joey R. said:
Hey Brian, glad to hear you are going to be on one of our rigs. If you hit any snags, please let us know!

As far as stereographers, well, the title itself has become just way too vague and unregulated. It turns out you don't have to prove yourself to give yourself the title of "Stereographer". As it turns out, something as simple as attending Sony's 3D course is all you need to throw that title onto a business card. Then there are conversion (2D-3D) Stereographers which I feel should be distinguished between practical Stereographers who actually "shoot 3D".

As far as the 2% issue, this is where being a good Stereographer comes in. Knowing when its ok to break that rule. Because there are occasions.

And as those that have responded have mentioned, PRACTICE! You would be amazed at what just two days of test shooting will net you.
Click to expand...
 
Brian Rocafort said:
What size are the allen key set screws that correspond with the hard stops underneath the Quasar motor box? Are the hard stop screws metric?
Click to expand...

3/32" and pretty much every bolt is Imperial. Ok one or two are Metric ;)
 
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