Found this article.
Quite interesting.
The BBC is lining up boxing and gynmastics as its lead sports for a 2012 Olympics showcasing 3D and Super HD TV.
But the corporation is unlikely to launch a dedicated 3D channel for the Olympics – using live venues and ‘red button’ event streams to air the coverage.
Sports with a sense of depth and confined space are expected to make the most impact in 3D, but major field games will also be captured to ensure the BBC has an archive packed with 3D and Super HD.
“The compact space of a boxing ring gives a real wow factor,” Roger Mosey, the BBC’s director of London 2012, told trade paper Broadcast.
“And with gymnastics, if you think about someone doing a vault, they start a long way away and move towards you – there is a real sense of depth.
“Team games and big pictures don’t really work – corner shots in football are good but often the players look like little models running across the field.”
International broadcasters are set to give their requirements for 3D, Super HD and other feeds to the Olympic Games’ official broadcaster, OBSL, this summer.
http://www.broadcastnow.co.uk/news/broadcasters/bbcs-3d-olympics-plan-shapes-up/5013262.article
Showing posts with label orthostereoscopy. Show all posts
Showing posts with label orthostereoscopy. Show all posts
Tuesday, 29 June 2010
Wednesday, 14 April 2010
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.
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.
Sunday, 21 February 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...
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...
Friday, 1 January 2010
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...
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...
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