Biology + Psychology + Technology = 3d

The eyes are NOT film cameras. So stop trying to 'think' like a camera when you are trying to visualize a shot or a frame or a scene... This is the first major hurdle when you are a 'died in the wool' time-served 2d director such as me. 13 years in London, 2 years in the States, 6 months in Belfast, 6 months in Cardiff, 4 years in Manchester. That all adds up to 20 years of years 'thinking in 2d'!
To create good watchable stereo 3d that doesn't pull your eyeballs out of their sockets, you cannot rely solely on the Technology. You have to begin with 'how we see' and how the brain uses 'what we see' and combines that information with a whole load of other factors before you even get a camera out of the case...
At this point in the blog I should bring into the frame my new best friends. Dr Bernie Harper and Rob Black. They are from Liverpool University Psychology Dept and they eat, sleep, drink, walk, talk, 3d! They think and communicate only in 3d! It took some adjustment from them to be able to talk to a numpty director like me and start to explain and unravel some of the complexities of stereo 3d. Dr Harper (Bernie to his friends) has been 'doing' 3d research for 10 years and knows more about 3d than is good for the mortal man... Rob Black on the other hand is a Perception Specialist / Consultant and he can show you things in 1d, 2d and 3d that you never knew existed! So Liverpool University, has a world renowned psychology dept. and I would have access to some of their greatest minds to help me learn about 3d. I was psyched
Who was it that said? : "I could teach you everything there is to know about 3d in an afternoon, but it would take you a lifetime to understand it." Sorry if that is a bad quote, but it make the point. It is such a complex area that if you fancy having a go then good luck. Throw yourelf into it and prepare to fail! And understand you cannot 'fix it in post' - It doesn't work like that!

What is Native Screen Pixel Parallax? NPP

What is Native Pixel Parallax?
Well, put simply - this is the concept that by basically using some maths, you can calculate 'what works' in pixels on your screen.
Explanation: When we shoot 3d with two cameras, it is the vertical disparities (the differences) between left and right camera that the brain 'sees' and then tries to 'fuse' the images and create an artificial state of mind that makes us 'see' depth or '3d'. So the distances between those cameras should be equivalent to or near to the natural 'interocular' which is about 65mm. (2 and a half inches in old money...). If the disparities are too much then it gives you a headache and makes watching a 3d sequence a very uncomfortable experience, in some cases if the disparities are too extreme it will mean there is no picture for the brain to fuse and it just shuts down any attempt to 'fuse' for depth.
Now here is the problem, if you shoot your 3d footage and for whatever reason you have had to shoot at a larger than 65mm interaxial, you may well end up with some stereo footage that 'works' on a small computer screen, but will not work on a large 3dhd plasma - or possibly, you may have a sequence that works on a 46" 3dhd plasma - and equally it won't work on a 30 foot cinema screen.
So some of the world's Stereographers have come up with a plan. They have come up with a numeric chart of 3d 'depth' that allows for average screen sizes and average distances from the screen. Obviously this isn't a perfect science, but it's a start... (Note to reader: It's quite hard 'blogging' about stereo 3d production, because not all the experts agree on certain principles... They all seem to have a different viewpoint to the same problems. So my position is try and be polite and take on board everyone's views and then when I am in the position of filming use the different advice as required....)
So here are some of the maths involved. You decide.
A 30 foot cinema screen = 360 inches (30 x 12inches) Human interocular = 2.5 inches
2.5 as a percentage of 360 = 0.7 percent - Now take that as a percentage of the resolution (2K)
then you end up with 14pixels. So any disparities larger than 14 pixels would represent an unnatural disparity which we have trouble fusing...(Based on 2k resolution on a 30 foot wide cinema screen)
Now try a 46" plasma. Width is less than 46" (The manufacturers get that measurement by measuring diagonally corner to corner of the screen) The width is about 40 inches so if we do the same thing and take
2.5" as a percent of 40" we end up with roughly 6 percent. If the Pixel resolution of the screen is 1920 x 1080
then 6 percent of 1920 should give you about 115 pixels. So theoretically you shouldn't go over 115 pixels on a 46" screen.
Simples?
When we look at 'Infinity' our eyes are parallel and anything we see across the depths will have 2.5" disparity.
The thing is when you 'scale' an image down (less than life size) to fit onto the 46" screen, then surely the disparities would be scaled down, or we are 'seeing' something totally unnatural?
If we only ever filmed Ortho stereoscopically (all measurements = real life) and then we only ever viewed our material back at life size on a large cinema screen - everything would be fine. A 6 foot man would be 6 foot tall and the disparities would be the same as real life - nothing over 2.5".
In reality we have to shoot for a range of different screen sizes - therein lie the problems. My conclusion is that whatever size screen you are shooting for always try and get the cameras as close to a natural condition as possible. If you are 'over' or 'under' the magic 2.5" then some post production can correct some a percentage of error.
Finally, you may deliberately shoot over or under for a special effect! But try not to blow the viewers mind! I am learning by trial and error. Everyday I shoot some more stuff and then work it out.

Stereo 3d and Liverpool University

My few baby steps in learning how to shoot stereo 3d produced some results...
A very impressive anaglyph quicktime that when you watched felt like an alien spaceship was hovering above your head and was sucking out your visual cortex with a Star Trek transporter!
clearly I had a way to go...

Enter LIVERPOOL UNIVERSITY in the North West of England.

As a self confessed 'businessman' in the film industry, I applied to the Regional Development Authority for a Training & Innovation Grant', and I was absolutely amazed when I was successful! Great, I thought, I'll be heading down to Pinewood, Britains very own film industry, to play with the professionals and learn all their secrets... but NO, it was not to be. What happened was that the Innovation Grant wasn't money in your hand, it was 'training to the value of...' with one of the regions 'knowledge providers'. Which I found out in my case was to be Liverpool University. What could I learn at my age and with my experience in the film and tv industry, by going back into 'academia'??? The answer, as it turns out, is a fantastic amount.

Stereo 3d is 1/3 biology 1/3 psychology and 1/3 technology.

This is the first BIG thing to learn in stereo 3d, especially as a director and stereographer.
Learn and understand the biology of the human vision system (also known as 'eyes').
Our eyes are NOT video cameras, they don't zoom or 'pull focus'. they are NOT 3d imaging devices.
Learn and understand the psychology, or in other words how your brain 'sees' - How it interprets the monoscopic depth cues to provide a depth map of the environment and how it combines all the information from all its 'sensors' with sight, and also how the brain combines its existing data on imagery and spatial awarness to navigate us and help us interpret what we see...
Learn how the technolgy that is available to us as filmakers and stereographers can be used to best effect to tell stories, evoke emotion and 'paint' 3d pictures based on reality...

As I start my training with Dr Harper and Rob Black I am getting to see the importance of at least getting a basic level of understanding of the biology and psychology of stereo 3d if I am ever going to be able t0 shoot and direct a high standard of stereo 3d.
The technolgy is easy in comparison! You hand over responsibility to the guys with the big rigs and hand over some serious bucks at the same time! BUT, I have learnt that you really need to get a thorough basic knowledge of 'how we see', and 'how our brains interpret what we see'. THEN you can play games with technology to do the film makers thing... and around creating non real 3d reality!

I think I may be turning into an OCD 'Ortho' Stereographer - or pehaps that should be OSD - Ortho Stereo Director!
As I carry on my stereo 3d jouney I have come across 'purists' portrayed as amateurs and Hollywood Stereo crews portrayed as 'Industry Experts' . But I am starting to worry about this battle over the I-O (the distance between the 2 cameras when filming)...
I need to go and find out more.
Stay tuned as I report back daily...
Cheers
Reg Sanders - UK Stereographer http://www.shoot3d.tv/

Florette TV Commercial (2d) Feb 2010

I know this is a 3d blog. BUT I have to earn a living while the production community in the North West catches up with the rest of the world! Being a totally unheard of commercials director (not based in London or the South East) is quite liberating in an odd way. You have nothing to prove, no 'reputation' to live up to...and you avoid some of the more incestuous aspects of the business. The other thing is that I am really lucky having a company like The Mob Film Co represent me, because they have world class features directors on their books and so it shows they really have a superb reputation. The top directors in the commercials game can pick and choose who they work for. Ergo, if I am on their books - they must rate my work, because frankly they could pick and choose and boot me off in a instant. The other plus is that I sometimes get to pitch for big national and global brands - like Florette - those lovely 'crispy Salad' people. Their Ads have always been towards the surreal and fun end of the scale and so I guess the agency saw a something in my mad reel that appealed to them! The creative was great fun, and the development process went smoothly. Pre-prod was tight for time, but we got there. The guys at the agency are hilarious - well, they did dream up the whole Crispy Salad idea, and the wonderful world of Florette!
We filmed in Cheshire in one of only four 'Cruck' barns left in the country, a curious 16th century, European looking barn, it was a cold winters morning yet with the lights on and the superb set design by Paul Kondrass it looked amazingly late summer / autumnal! The DoP was Steve Weiser, a master at painting with light, and the shoot went flawlessly. You can see the finished results on TV - the deliciously fruity fruit segments, fresh from Florette! Look out for mad dancing people in a barn chopping fruit with their hands in a fruity ritual...
Directed by yours truly, shot in Arley Hall in Cheshire, edited by Olly at Delicious Post on Wardour Street,
audio at Grand Central and on a screen near you soon! (throughout 2010...).

Motion artefacts / temporal occlusion 101 - JAN 2010

Yesterday, Simon Stappleton from Procam North and I, and Dr Bernie Harper from Liverpool University took two Sony XD cams off the shelf to take a look specifcally at motion issues as I had read some stuff on line about 3d blur and movement and how things can get tricky when shooting movement. I wanted to find out for myself what happened under different circumstances. During my 3d training I have come across loads of people in the film and TV bizz who are full of advice and are quite happy to tell you how it should be done... But then when I asked the questions, I found out that although everyone is ready with advice, NOT MANY have actually shot 3d!(I guess thats just a bit like life...)

We put the cameras onto the prototype Procam SbS Plate, a special plate that Jonathan Bolton at Procam North had engineered so that we could mount ANY camera Side by Side for trials. When you are training it's hard to get access to large mirror rigs, apart from the obvious reasons of cost, ie you need a team of Nasa trained scientists to program it, align it, and 'fly it' for you. Pretty much all of that technology is very expensive to hire, and because 3d is the latest 'in thing' particularly in London and the South east, access is very limited.

Training - is limited and expensive, but if you have the money then Pinewood and Shepperton run 3d training courses. Actually, on the subject of training I was very fortunate in being able to secure an 'Innovation Grant' from the RDA in our region, and that was used to get me superb access to some of the keenest and most intelligent minds on the planet who have been living and breathing 3d for 10 years or more. Now at last the technology is catching up...

For our motion test shoot we shot a variety of settings - interlaced, progressive, different frame rates. We filmed loads of cars driving by and I spent hours in Noise Industries Dashwood Stereo 3d Cinema Toolbox looking at disparities and basically trying to understand what worked, what looked good and what looked bad. Whether or not to track convergence on the passing cars or leave convergence set at an optimal distance. I will talk about convergence in a separate post because it is another of those 'sensitive'' areas in the 3d community, and the idea of this blog is not to cause stress and anger, but to raise the issues for discussion...
In terms of motion - Point One: I would always shoot progressively for motion. Full stop. end. new para.
Yes, you can play with frame rates and electronic shutter speeds - but you must shoot progressively because of how the frames with movement on have motion artefacts when shooting interlaced. You may have seen it yourself in 2d TV - that weird jagged edge where the scan lines have captured slightly different moments in time so a waving hand breaks up across scan lines. If you combine stereo shots with this effect you end up with a mess that the brain can not fuse, so no 3d. Always shoot motion progressively.
Point Two: Your cameras should be synced or 'gen locked' so that each frame is written and captured at the same time - that is to say the beginning of each frame must start at that 1/50th or 1/25th of the second (or 1/60th) and scan each line, both camera's perfectly in sync. Line 1 right eye camera, scans at the same velocity and the identical moment in time as Line 1- left eye camera and so on through the full frame scan.
So Progressive and genlocked / synced. We did try some early days tests with 2 HVR-A1's that were not 'genlockable' but were synced through a dual lanc within 100ms and on the whole the results were not bad. Though we weren't filming anything with much movement - just some stuff around 'sets' for a tv drama, kitchens, living room, that kind of well lit set up in a TV studio. We used a digislate to mark top and bottom of each take to see how the sync help up over time and it was reasonable and useable.
Definitions:Motion artefacts - weird bits of video that are created when the technolgy has to 'predict' what the movement in the frame is - or how the technology sometimes fails to capture the action properly.
Temporal Occlusion - when the differences between the two shots are caused by time, by the the way the 2 cameras have recorded or 'captured' everso slightly different moments in time, and so they don't work in 3d.
My final thoughts - you can shoot on interlaced formats - I use 2 little HD JVC's shooting AVCHDs or MPEG.TS for 'Pre Viz' and ' recce' . They are not locked, not synced and interlaced!
But they show me enough to see what works and what doesn't work...

3d stereoscopy shallow depth of field issues

"Most professional directors spend a great deal of time and effort shooting on 'longer' length lenses for that beautiful shallow depth of field... And therein lie a few problems when you move into the world of shooting Stereo 3d..."

Simples.

The above statement has several pre-supposed observations. Perhaps I should preface it with "in my expereince as a BBC trained Drama / Commercials 2d director, I generally find myself choosing lenses from around the 50mm slot in the box of primes, and upwards.
(Except the last commercial I directed for Florettes in which we had a 'wide' on a 35mm. But on the whole my favourite lens is the 85mm.)

The thing I have discovered since training as an Ortho-Stereoscopic director in 3d - is that it is a trade off between the number of depth cues that you can fit into a 'tighter' frame, versus the shallow 'film look' depth of field.

This is an area I would like to explore as I develop my reportoire in shooting Stereo 3d...

A Christmas Carol - Not a good 3d experience DEC 2009

On one of those rare 'days off' moments - I decided to take the kids to see a 3d movie, kind of busmans holiday! Nevertheless we turned up at the local multiplex which had recently had its main screen converted to 3d.Infact, it was using the new Dolby 3d system which I had read was vastly superior to the Real D system, so I was keen to hand over my hard earned and get into the cinema... We took quite a load of kids with us, as our kids brought their friends who brought their friends! We ended up with 12 kids and 3 adults.

The first thing I noticed was that the glasses were duly handed out, beautiful shiny mirror look lenses and deep wrap around sides. I later discovered this is to maximise light the coming into each lens. During my stereography training I was told that the Dolby 3d system uses a combination of filtering to very finely control the colour information to each eye, so that although the channel separation is slightly less than the Real D polariser system the final result is better overall colour reproduction. I was looking forward to this screening, probably more than the dozen kids I was sat with!
I noticed there was a lot of activity pre-movie as the audience kept popping up and down to the attendant getting 'wipes' for their 3d glasses, getting them cleaned. I had to for some of our kids.
As the lights went down and the opening title sequence began I noticed I could see something in my lenses.
Again I cleaned them but it wasn't on the lens. What I could see was the reflection of my eyes and eyelids and lashes in the lens, as they were so shiny. Also the ambient light in the auditorium was very high, not helping the situation. In the UK they have strict regulations governing light levels in cinemas, and generally the cinemas have 3 levels. The walking in / walking out level well lit 'house lights' - then the next level of dimming is the spot reel or the adverts before the main presentation, I assume they have that lighting so that we can juggle our popcorn and kids, and get settled for the main movie. Finally, darkness for the main feature.
However, in my cinema trip, the lights never dimmed down to full darkness for the movie. You could extend your hand out and clearly see a shadow cast on the floor from the lights above. This caused problems with the 3d viewing because the images I could see through my lenses were overlaid with reflections, also the movie itself had a fairly 'dark' feel to it (being set in Winter in Dickensian London).
And therein spoilt what should have been a great 3d experience. The trouble is these multiscreen movies have very few people involved in their running. It's all done by computers... as they say. A Christmas Carol started and I went off like Scrooge trying to track down the projectionist. I went to the front of house area, to find a couple of students selling popcorn and coffee, they told me the projectionist had 'gone home' and would be back later to turn everything off... I asked for the manager, there was none. So the next day I'm on the internet and phone trying to find someone from the Vue Cinema chain to talk to... No luck. I sent an email to their customer services team who eventually reply with some brush off corporate letter about local planning regulations on light levels in public buildings... And didn't take on any of my points about 3d needing more careful light control than 2d so that the viewer can properly extract disparities and depth information for proper 3d viewing. I think they were worried about me trying to get my 50 quid back from them for the trip, but I made it clear I just wanted some technical dialogue on their procedures and spec for 3d cinemas... Bah humbug!