Stereoscopic 3D Workshop 05.01.01 CRAIG LEES RAVENSBOURNE MA BROADCAST FUTURES Stereoscopic 3D productionDifference between 3D and S3DStereoscopic 3D is based on the illusion of recreating Human binocular Visionby using two sets of images captured with slight positional disparities to createperceived depth. This effect is known as Stereopsis.3D describes real or computer-generated three-dimensional objects and is alsothe term more often used with CGI, 3D modelling and VFX.Natural Depth CuesOur brain interprets depth through a number of differing two-dimensionaldepth cues such as occlusion. When objects are covered by other objects, ourbrain registers them as being nearer/further away to us.Other natural depth cues include relative size of objects, saturation (objects’colours desaturate the further away they are).Depth PerceptionConvergence/ DivergenceParallax – Negative and PositiveThe business case for 3DWith the success of Avatar at the Box Office and the Sky Pub 3D experiment, 3Dmovies are noticeably attractive as ticket prices are elevated and 3D in the homenaturally has extra revenues for income for manufacturers.
Aside from monies from 3D film ticket sales at the cinema, there are a plethoraof 3DTV channels set to hit our screens over the next year.3D storytellingS3D has a great opportunity to produce different creative tools. Not only can wemake things appear come out of the screen and into the screen, we can alsomake objects appear smaller or greater than what they are (dwarfism andgiantism).
Stereoscopic Technology3D or not 3D?As of yet there is NO universal standard or format.Public adoption of 3DTV is an unknown entity. The screens are relativelyexpensive with many around the sum of £2000.Examples of differing formats:Circular polarising Passive technologyActive Shutter Technology
Glasses-free Autostereoscopic Displays using Lenticular or parallax barriertechnology from Toshiba, expected to be released at ChristmasStereoscopic 3D laptop Live 3D –The engineering challenge of getting it right in real-timeTelegenic UK Outside Broadcast provider commissioned by Sky 3D to deliver3D broadcast using Sony cameras and 3ality systemsDigital technology innovation has made Live 3D possible.Sony System: SIP, P1 / HDC 1500 camera systems, Passive 3DTV monitoring
3ality Digital systemsTS-2 Studio Beamsplitter Rig
Motorised Lens systemTS-2 Studio Beamsplitter Rig on Ped
Sony HD CAM SRW-1 Deck – records both video feeds onto one multiplexedformat3D Village and Video Village
3ality 3D monitoring on a 2D screen using luma difference 2% parallax grid3ality 3D monitoring metadata
3ality 3D monitoring alignment and depth budgetFusion Pace Rig – Engineered by Vince Pace. This system was used onAvatar, The Final Destination plus recently used on the upcoming TR2N 3D.James Cameron on Pace Fusion 3D rig
Pace On LocationArri Alexa Cameras mounted on Pace Fusion 3D Segway Rig on Martin Scorcese’sThe Invention of Hugo Cabret at Sheperton Studio
The Stereoscopic encode format is Side by Side compressed within a 1080i25frameTo enable the 3D program to retain the highest quality throughout, a minimumof 90% must be native 3D footage.Stereoscopic AlignmentThese guidelines are for the final Program content being displayed on screensizes in the range of 46" to 70": Main subject point should nominally be the screen focus point or convergence point of the two images Positive disparity or image separation at distant points (into the screen) should not exceed 2% for majority of shotsNegative disparity Image separation at close points (Out of Screen) should notexceed 1% for shots.Record format should be at a bit rate no less than 100Mbit/s 4:2:2 for acquisition.S3D Cinematography TheoryThe Stereo Window – think about shooting within a window to avoid edgeviolations. Monitor BOTH cameras.Calculating 3D depth for a scene – the variables of screen sizeConverged cameras Vs Parallel cameras – weigh up the pros and cons for whatis best for your shootPre-visualisation – weigh up the best solution for your production – DOES NOTHAVE TO BE EXPENSIVE!Controlling depth – The Depth Bracket and depth script. How much depth doyou want in the scene to express your storytelling? What should be the Interaxial distance: Hyper stereo, Ortho-Stereo or Hypo stereo? Pre-production isVERY important in Stereo 3D.The effect of screen size upon the 3D effect – What is your final output? Thisimpacts on whether you should employ 1/30th / 1/100th laws for stereoscopiccinematography.
The importance of Metadata – When using VFX, it is very important that yourecord stereoscopic camera data for your VFX artist to match effects. What is theIA? What is the distance to nearest/furthest distances? What is the focal length?What is the F-stop?Twice the number of cameras is required for a native 3D stereoscopic 3D camerasystem. This results in TWICE THE DATA.Zoom Lens problems: telecentricity errors, also known as zoom wander.The effect of different focal lengths. Wider lenses create a greater 3D effectwhereas longer lenses tend to flatten the 3D effect.Lighting. Reflections, high contrast imagery shadows and specular highlightsoften create visual artefacts in stereo 3DThe importance of using shutter-sync camerasCameras with Genlock syncFigure 1, R Cam 1 frame before clap L Cam 1 frame before clap Figure 2, R Cam at clap L Cam at clap
Cameras with Temporal sync (shutters NOT synced)Figure 3 L Cam 1 frame before clap R Cam 1 frame before the clapFigure 3, L Cam at noise of clap R Cam at noise of clapFast moving objects in temporally synced cameras can cause Retinal Rivalryartefacts, as we are seeing different images between our left eye and our righteye, which can cause discomfort. The greater the size of the screen, the moreretinal rivalry is amplified. S3D Pre-ProductionDepth Budget and Depth ScriptEach scene will have a designated depth budget associated with it for astereographer to work with on set. This budget will be created using a variety offactors including feel, continuity, and broadcast/cinema specifications. A depthscript will be constructed in the post-production process and are likely to havedecisions regarding Inter-axial and convergence settings. Note that thougherrors in convergence can be easily corrected in post, altering the inter-axialdistance is very difficult. To date, only highly expensive systems such as Mistika
and Occula are capable of changing inter-axial distance in a scene, furthermore,the large computational data required by this interaxial operation means thatthese advanced programs cannot render these actions in real time.The depth script is constructed in the form of a graph that tracks the filmmakersemotional intended impact of each scene. These depth decisions can be created
in the script with signifying notations such as; C-5 (lenses strongly convergedso that the action very much happens in the viewer’s lap – lots of negativeparallax); C-0 (placing key subjects on the screen plane); and C+5 withmoderately converged lenses pulling the viewer into the screen space.As well as convergence decisions, another major component of the depthbudget is the required interaxial distances that each scene should contain,which again is very much part of the pre-production process. Due to inter-axialdistance being the single major influence over perceived 3D depth, attentionshould be noted upon interaxial distances and that they do not jump from oneextreme to the other. Such extremes produce uncomfortable depth cuts uponthe viewer. Also, interaxial distances have an effect upon scale. This sense ofscale, due to exaggerated inter-axial distances, brings filmmakers theopportunity to enhance the emotional impact of their stories (Alice inWonderland, where Alice grows taller and shrinks being a great example).Narrow inter-axial distances invoke gigantism effects (making the subjectappear larger than what they are). Wider interaxial distances causeminiaturisation effects (making subjects appear smaller than what they are).These scale decisions can be notated in the script much in the same wayconvergence notations do such as I-5; I-0; I+5 , where I-0 indicates orthostereo(human interpupillary distance – 65mm or thereabouts), I-5 indicates theinteraxial where the lenses are narrowly separated (hypostereo) and I+5 wherethe lenses are widely separated (hyperstereo).The depth budget follows the decisions made within the depth script and ismaintained by live 3d pre-visualisation measuring tools such as the 3alityStereo Image Processor (SIP 2100) and the Sony MPE-200 SIP, or by simply usinga grid overlay on the multiplexed stereoscopic imagery.
Things to consider3D uses double the bandwidth of usual video editing as two video tracks areused to create every S3D shot. Spec your machine for a faster stereoscopicpipeline.Depth CutsFloating Windows.Slower cuts for shots with lots of perceived 3D depthMultiple S3D viewing and output modes are very usefulOrganise your media.ProductsCineform (Mac & Windows) Neo 3D around £2000 and Neo HD (under £400)Stereo 3D Toolbox (Mac) Final Cut Pro Plugin created by Tim Dashwood (around£800)Avid Nitris around £10KMistika around £100KQuantel Pablo 3D around £100KSmoke (Mac & Linux) around £10KAfter Effects CS5 scripting and expressionsPremiere CS5 – now has stereo functions and can handle 4K Red footage (withNvidia Quadro Graphics Card) – VERY EXCITING! Shows how powerful non-linearedit systems (NLE’s) are becoming.DIY 3D - Stereoscopic 3D on a budgetBuild your own rig
There are benefits in shooting parallelStereoscopic player – available from 3tv.at Dual firewireNeo Player – Cineform’s Player allows you to play the Cineform S3D Codecs onyour machine using a 3D display.Adapt your existing HD kitVizard – Build your own 3D theatre – Wired magazine articleZalman Monitor – Full colour Passive S3D under £300Anaglyph monitoring – 3D monitoring on a 2D screen (VERY cost effective)NVidia 3D vision solutioniZ3D – stereoscopic 3D gaming on a PCStereo 3D Toolbox by Tim DashwoodToday we will learn the basics of the FCP pluginStereo 3D Toolbox.Why? It is VERY stable and has lots of fineextensive stereo tools, which can produceeverything you need for your S3D productions.Exercise OneMaking a StereopairSync your clips together for your Left Eye Clip andRight Eye Clip. Make sure they have the samestart and finish points. If they don’t, trim them.
Once you have ensured they are temporallysynced and are the same duration, double clickeach clip and then Make a Subclip (Command Ufor you hot key freaks out there – like me!).This will make a subclip in your browser.Do the same for your Right Eye temporally syncedclip.NOTE – Why do we have to make subclips?:Well, FCP recognises start media and end mediaonly in your video clips. It is very difficult to gettwo cameras two record at EXACTLY the samemoment of time. Making subclips is the fail-safeway of ensuring your clips start and end at thesame point in time. Setting In and Out points alonedoes not work!Once you have made a Left and Right Subclip,which you can see in your browser, we can nowmake our stereopair.
NOTE – your clips will be named depending onhow your media is captured. When usingtapeless, make sure you use Log and transfer toname your clips - TRUST ME - this will save youlots of pain later!!Then, drag your Left eye clip into your timeline.Once there, double-click your Left eye clip, thengo to Effects – Video Filters – Dashwood Stereo3D Toolbox (NOT the LE lite edition) – Stereo 3Dclip coupler.
Click the Filter Tab. On the S3D Input, Select Clip=Left eye & Image Well = Right Eye.
This will enable your Left Eye Clip to be theMaster Clip and it will create an Image Well thatyou can drag and drop your Right Eye Subclipinto to create your stereopair. Keep the S3DOutput Mode as Side by Side at this stage. If youhave your Left and Right Eyes the wrong wayround, You can select the Swap Output tab, butgetting it right first time is VERY GOOD PRACTICE!
Once you have created your stereopair using ClipCoupler, you then want to geometrically alignyour clips in order to produce the desiredstereoscopic effect.To do this we double click our clip – Effects –Video Filters – Stereo 3D Toolbox – Stereo 3DGeometry.
Click on the filters tab for the stereopair clip, if notalready, to reveal the Stereo 3D GeometryControls.
Once the Stereo 3D Geometry Controls Tab is up,we can move the images around to create theaspired stereoscopic effect. This is the fun part asthis is where the S3D comes alive.Depending on how you have shot yourstereoscopic material, whether it be parallel orconverged, the amount of applied geometricalalignment will change. If the material has beenshot using the parallel method, we will need toapply what is called Horizontal ImageTranslation (HIT) to the two images, whichbasically involves sliding the two images
horizontally over each other until they slightlyoverlap to the point of convergence that bestsuits the material.Anaglyph Stereo pair with no HIT appliedAnaglyph Stereo pair with HIT applied
To adjust HIT, use the Convergence Slider in theStereo 3D Geometry panel and change the S3DOutput mode to the appropriate 3D viewing modeyou are using, this may be interlaced for passivescreens such as the Zalman, side by side for 3DTV’ssuch as the JVC or anaglyph if you are using astandard 2D screen.Use the Convergence % Course slider first to get asclose to the required convergence point possible,then use Convergence % Fine to make finelytuned, more accurate alignment adjustments.If you have vertical misalignments, use twirl downthe Disparity Correction triangle to release thevertical alignment controls.
Other misalignment errors that you may wish to fixinclude Rotation, Zoom, Keystone (these are allquite common), can all be fixed here in the Stereo3D Geometry controls.
How do I measure my 3D effect?There is a great tool in the Video Generator tabwhich can be accessed by selecting - DashwoodStereo 3D Toolbox – Stereo 3D Parallax guides.
These Parallax Guides are REALLY useful as ameans to measure how much depth you havecoming OUT of the screen (Negative Parallax) andback into the screen (Positive Parallax) within eachscene.And this is where good old anaglyph monitoring isreally useful.TIP – Negative Parallax (coming out of the screen),the disparity ‘fringing’ will be GREEN on the left.
Positive Parallax (going back into the screen), thedisparity fringing will be RED on the left.If it’s not, you have got your eyes the WRONG WAYROUND! Don’t stress though, this is a commonmistake when first starting out!You can set the guides to a matter of percentage,which is good, but make sure you are monitoring ona screen the same size of your final output screen.The Sky 3D Guidelines are 1% negative parallax and2% positive parallax, which is a pretty good rule tostick to though you may want to push this furtherwhen displaying on smaller screens below 50”.
To select parallax guide controls, click the controlstab, then select custom parallax %, then change theslider (or type in the value) to 1% custom parallax.
Then drag this video generator onto your timelineabove your stereopair.Now you can measure your 3D! Measure the fringingdisparity of the object closest to the camera tomeasure your maximum negative parallax (furthestout of the screen object which has green fringing onthe left), and measure your maximum positiveparallax (the furthest behind the screen objectwhich has red fringing on the left).What is the measured 3D Depth in this scene?
Yes you can change the colour of the parallax guides – Veryuseful!Expanded view of the open window. The yellow marks show how thestereo infinity positive parallax divergence rests measures 1%.
Analysis of SceneMa ximum p ositiv e p a ra lla x/d isp a rity 0.8 %Ma ximum ne ga tiv e p a ra lla x/d isp a rity 1%,Based on: IAD 20mm, focal length 7.6mm, convergence point actress(2m), closest point shaven-headed actors shoulder (1.6m) , furthest pointtree-line above house outside (50m)……………………………………………………………………………………..........Ok, that is the end of this introduction to the Stereo3D Toolboxplugin and Stereoscopic fundamentals.There’s more than enough here to keep you going for some time inyour beginning adventures with S3D. There are plenty of other usefultools within the plugin such as creating 2D text in 3D space andDisplacement Maps but for now concentrate on these tools to buildyour stereoscopic stories.And questions or help required, email me at email@example.com I will try to answer your questions as quickly as possible.Thanks and good luck new 3D movie-makers!Craig LeesRavensbourne MA Broadcast FuturesFurther research materialBernard Mendiburu’s 3D Movie Making from Scriptto Screen.
Lenny Lipton’s classic “Foundations of theStereoScopic Cinema. A Study in Depth.”