Partners for this white paper : The Ficam (Fédération des Industries du Cinéma, de l’Audiovisuel et du Multimédia), presided over by Thierry de Segonzac, is a professional organization bringing together 180 enterprises whose activity covers all the professions and technical know-how dealing with image and sound. Always proposing strong measures, the Ficam represents, promotes and defends the national and international interests of technical industries dealing with audiovisual creation. THE 3D CONSORTIUM The Commission Supérieure Technique de l’Image et du Son (CST), presided over by Pierre-William Glenn is an association grouping professionals in cinema and the audiovisual and multimedia fields, launches 3D rendez -vous as well as technicians and technical artists. The CST brings together today close to 700 members. Its goals are to defend the quality of the production and distribution of images and sound, defend creativity and technological and artistic innovation in cinema and the audiovisual fields, as well as to defend the independence and freedom of action and expression in our professional activities. A UNIQUE MARKET PLACE UP3D (Union des professionnels de la 3Ds) is an association whose objectives are: to bring together and animate the 3-D professional ONE TO ONE MEETING - BUSINESS NETWORKING community, inform and communicate on the professions, know- how and equipment specific to the 3-D world, and to promote and WORKSHOPS - BOARD DEMO PRESENTATION develop 3-D in Europe. Originally composed of 17 members, the HD Forum, presided over 6 ZONES by Jean-Pierre Lacotte, now has 51 members, all professionals as stated in the statutes. The diversity of the questions to resolve around HD has led the HD Forum to create two commissions: the MIDDLE EAST - BRASIL - NORTH AMERICA “technical commission” and the “communication and marketing commission”, which are themselves divided into work groups that RUSSIA - INDIA - CHINA regularly collaborate with the work of the Ficam and the CST. FOUNDED BY : The AFC (Association Française des Directeurs de la Photographie Cinématographique), co-presided over by Matthieu Poirot-Delpech, Michel Abramowicz and Remy Chevrin, brings together most of the SPONSORED BY : directors of French cinematic photography at the highest artistic and technical level of French and foreign productions. The AFC promotes the existence of quality cinematic images, tests new techniques and affirms the competence of photography directors as creative collaborators of film directors, in the best tradition of French cultural and artistic discourse. firstname.lastname@example.org
1 SOMMAIRE 0 0 FÉDÉRER ET PROMOUVOIR LES INDUSTRIES TECHNIQUES DU CINÉMA, DE L’AUDIOVISUEL ET DU MULTIMÉDIA 1 Why a White Paper on Stereoscopic 3-D* (3Ds)?? PAGE 8 1 ma 0 Technical industries iné Fundamental Principles of Stereoscopy PAGE 10 0 c of creation audiovisuel RIGS AND STEREOSCOPIC CAMERAS PAGE 20 1 LIVE MULTI-CAMERA 3DS CAPTURING PAGE 24 0 00 1 3Ds POSTPRODUCTION: CORRECTIONS AND WORKFLOW 1 PAGE 25 00 1 1 1 2-D/3Ds CONVERSION: THE NEED FOR KNOW-HOW PAGE 30 1 0 0 0 VISUAL COMFORT WITH 3Ds PAGE 32 0 1 00 1 0 1 0 3Ds PROJECTION FOR FILMS PAGE 34 mult imédi 3-D TV DISPLAY PAGE 36 a 0 ADAPTING 3-D TO THE SIZE OF THE BROADCAST SCREEN PAGE 40 3Ds GLOSSARY PAGE 45 0 With over 180 member companies, APPENDIX 1: DEFINITION OF 3Ds PROFESSIONS PAGE 47 the Ficam represents and promotes the technical industries of Cinema, APPENDIX 2: 3-D FILMING TECHNIQUES PAGE 49 Audiovisual and Multimedia. APPENDIX 3: CODECS AND DISTRIBUTION MODES PAGE 54 www.ficam.fr FICAM (Fédération des Industries du Cinéma, de l’Audiovisuel et du Multimédia) 11/17, rue de lAmiral Hamelin-75783 Paris Cedex 16-Tel : + 33 (0)1 45 05 72 55-Fax : + 33 (0)1 45 05 72 50
8 9 Why a White Paper on Stereoscopic 3-D* (3Ds) ?E ver since movie theaters have been equipped with digital 3-D pro- production. In fact, stereoscopic 3-D, if it adds new possibilities on the jectors, a number of 3-D feature-length films have been shown narrative level, also includes new obligations on the technical level tied with often disparate processing quality. The television market has to the cerebral acceptance of cinema and television viewers. This is why,also decided to respond rapidly to the desire of the public for 3-D films. in this 3Ds white paper, our objective is not to constrain the creativityThe television manufacturers, quick to participate in this technological of directors, who should remain free in their artistic content, but to setcraze, now make flat television screens on a grand scale equipped with a framework for their being better able to get around in the additionaldisplay systems “in 3-D”, allowing the viewer to watch 3Ds TV programs production possibilities specific to stereoscopic 3-D.in conditions of quite acceptable visual comfort. Moreover, some smart- It is also important to specify that the study of stereoscopy,phones have recently appeared in the mass market which are capable already quite old, has allowed the visual comfort zones–inside which aof generating autostereoscopic 3-D. viewer will have no discomfort or, not to say headaches–to be empiri- However, the market for mobile, TV and cinema broadcast cally defined. Scientific studies are now taking place to refine these pa-hardware is much in advance, chronologically speaking, of the produc- rameters.tion capacity of stereoscopic 3-D content by the audiovisual and cinema We say also that the art of 3Ds is only at its beginnings. There will noindustry. Up to now, there does not exist enough natively produced 3Ds doubt be the possibility for directors of films or television broadcasts tocontent to furnish all the ad hoc broadcast media. The barrier is mainly go beyond this technical framework, at least from time to time, in ordereconomic and technological, but it is also a result of a lack of informa- to provoke quite new emotions in the viewer.tion on the practical conditions in which it is possible today to create Finally, it should be noted that the perception of the depth of anfilm in 3-D for television and cinema. object in a 3Ds scene is modified according to the size of the display of Due to the current deficiency in 3Ds content, it should be noted the images (movie theater screens or televisions). This white paper thusthat many 3-D films and programs broadcast in movie theaters, or on describes the different display technologies and defines the technicalthe first 3Ds television channels, use procedures that create 3-D from contours of future 3Ds programs to be provided for television and the cinema.2-D automated images. These do not sufficiently take into account the In fact, in order to summarize the main objective of this whitemain principles of visual comfort for the viewer and put into question paper, we would say that it consists of sufficiently informing audiovi-the notion of respect for the original work. sual and cinema professionals on the possibilities of 3Ds so that they Given this enthusiasm for 3-D, it seemed necessary for diffe- can appropriate this new language as much as possible, and that publicrent professional organizations of the cinematographic and television disappointment can be avoided for this new artistic and technical field,industries (Ficam, CST, UP3D, AFC, HD-Forum, etc.) to produce a white as might have been the case during the first wave of infatuation for 3-Dpaper laying out the current state of stereoscopic 3-D. The goal of this films in the 1950’s.white paper is to point out the different technical and narrative issuestied to the filming, postproduction, visual comfort, 2-D/3Ds conversion This white paper on 3-D refers to the state of the art in May 2012. It is theand display on a cinema and/or television screen. second version of the document that takes into account the remarks of Stereoscopic 3-D is an artistic and technical mechanism requi- French professionals and updates the generic ideas on the subject.ring a mental reconstruction of images, which is chosen by the directorand limited by the physiological laws specific to most viewers. As such, it is crucial to put in place, at every step in the manu- * Rather than use the terms “relief” or “3-D”, quite imprecise for thefacturing chain, 3-D monitoring and quality procedures supervised by former and source of confusion with computer generated images for thequalified personnel and trained in this new mode of creation and post- latter, we recommend using the term “3Ds” for stereoscopic 3-D.
10 11 Fundamental Principles ofStereoscopy How do we perceive 3-D ?L et’s look at a close object: for example Now, while continuing to look at the tip of our the index finger of our hand. Naturally, finger, let us consider the objects situated the optic axes of our eyes convergent behind our finger (Figure 2). On which sidetowards the object being looked at. We thus to they seem to be placed when we close onebecome slightly cross-eyed. The more the ob- eye and then the other? We notice that theyject is close to us, the more we become cross- are more to the left seen from the left eye andeyed: the angle of convergence increases. The more to the right seem from the right eye.more the object moves away, the more the It is what is called parallax. It is said that forangle of convergence decreases. The angle objects situated behind the plane of conver-of convergence is a very important indication gence, the parallax is positive. Let us observefor our brain: knowing the distance between again our finger and now consider the objects figure 1 figure 2 figure 3the two eyes, that are closerit can deduce (Figure 3). Thethe distance of phenomenonthe object, like is inversed: thea range-finder. object is more toThe brain allows the right seemus to perceive from the leftthe depth of the eye and morescene by way to the left seemof the differen- from the rightces between eye. For objectsthe angles of situated in frontconvergence of of the plane ofthe different ob- convergence, thejects being observed. Now let us examine the parallax is negative. In sum, the parallax isimages formed by our two eyes: as the optic zero for all the objects situated in the planeaxes of our eyes converge towards our finger, of convergence, positive for all the objects si-the image of our finger is formed at the same tuated behind the plane of convergence andplace on our two retinas (Figure 1). We call the negative for all the objects situated in front of figure 4same points of the objects in the left and right the plane of convergence. are then practically parallel and the angle of object can hardly be perceived. Happily, otherimages “homologous points”. It is said in this The more an object is distant, the more the convergence becomes too small to inform us indications inform us of the depth: occultation,case that the homologous points are fused perception of its distance is imprecise. When sufficiently as to the distance of the object. Be- relative size of the objects, perspective, the ef-and that our finger is in the “plane of conver- the distance of the object goes beyond several ginning from a 100 meters, the distance of an fect of mist, etc.gence” of our eyes. dozen meters, the two optic axes of our eyes
12 13 consequently the placing of the plane of How is 3-D reconstructed? 3Ds applied to cinema Stereography : a new production language convergence as well as the amplitude of the “scenic box” (see Appendix 2).W and television Creating for the cinema or for television is It should be noted that the size of the 3Ds T e now take two cameras in pla- not tied only to the techniques of produc- he fundamental difference between tion or broadcasting, but also to the emo- monitoring screen during filming does not ce of our two eyes along with a attempts in the past and the present necessarily correspond to that of the fi- tional connection that these images foster 3-D screen system whose role growth of 3Ds comes from the tech- nal broadcast. The stereographer should in the human brain. From this standpoint,is to make each eye see only the image nical mastery of 3-D in the entire chain of 3Ds requires that this connection be re- clearly inform the production team of thethat is intended for it. In Figure 4, the left the manufacturing and image broadcasting considered so as to adapt the conditions differences in the sense of depth accordingand right homologous points are repre- process. The use of computer tools during of creating a cinematographic or televi- to the dimensions of the film’s intendedsented respectively in red and cyan. If the shooting and the possibilities of modifying sion project to this question. 3Ds induces screen and to justify his “not visual” buthomologous points are superimposed du- images pixel by pixel up to broadcasting a rupture with the practices of production “provisional” adjustments.ring projection, the view will converge on are steps that from now on are indispensa- and which modifies the interpretation of The parameters of “depth” can be in- ble and in constant evolution. They guaran- the space as imagined by the director. One creasingly modified in postproduction. Gi-the screen and the object will be seen on tee the quality of the 3Ds image necessary should also note that, in studying certain ven this fact, just as the color calibrationthe plane of the screen. That is how one for the visual comfort of the viewer. gives the tone of the scenes in a film, the filming parameters such as lighting andsees films in 2-D. Digital tools take part in the mastery of “3Ds calibration” becomes an important framing, if there is a rupture between 2-DIf the parallax is positive, the view will stereoscopic production. Being more and 3Ds, it is situated more on the side of step after the film has been edited. It al-converge towards a point situated behind knowledgeable from this experience, we acceptance by the viewer’s brain than that lows for the perception of reality in 3-D tothe screen: the viewer will thus have the wish today to support the emergence of a of artistic practice. be given a general tonality and to provideimpression that the object is situated new cinematographic and television lan- In 2-D as in 3Ds, the director remains the 3Ds continuity between shots according tobehind the screen (as if seen through a guage tied to the usage of 3Ds. main judge of the use of 3-D in order to the final intention of the director.window). Finally, if the parallax is nega- A purely technical conception of 3Ds is serve his narrative, whether it is a question a risky bet. It is preferable to rely on the of a film, a telefilm or a televised program. Think about 3Ds before filmingtive, the view will converge towards a point savoir-faire, both technical and artistic, of In the same way that he decides a produc- If you want to have a quality 3-D effect, itsituated in front of the screen, and the the stereographers and technical service tion in 2-D, he formulates a particular re- would be useful to verify beforehand theobject will thus seem to be in front of the companies, which have both a solid theo- quest to the stereographer who will see to pertinence of the choice of 3Ds for this orscreen (as if popping out). retical knowledge and experience in 3Ds. its completion. The working together of the that film or television program from theIn sum: The production of a sequence in 3Ds can- director and the stereographer thus aims beginning of the synopsis or scenario. In• Objects situated on the plane of conver- not be summed up in an automatic algo- to establish “3-D behavior” (modulation of this way, a story unfolding in an aerial orgence during filming will be reconstructed rithm for creating 3-D effects, however the stereoscopic range), done through a aquatic universe lends itself totally to aon the plane of the screen (parallax zero). sophisticated it may be, or do without the graphic image or annotations on the script popping-out effect, for the objects can be• Objects situated behind the plane of onsite experience of specialized professio- or storyboard, which then serves as a guide “unglued” from any support, like levita- nals who know how to adapt to particular for the team doing the shooting. 3-D that ting in a fluid or a vacuum. Furthermore,convergence during filming will be re- filming conditions, very often full of unfo- is too strong can lead to visual discomfort longer shots and/or rather slow and fluidconstructed behind the screen: window reseen events. The creation of a 3Ds scene over time, while 3-D that is too weak risks movements of the cameras also favor theeffect (positive parallax). requires a perfectly regulated production frustrating the viewer. It is mainly within perception of a more comfortable 3-D ef-• Objects situated in front of the plane of with the camera angles completely maste- these limits that the director can choose fect. They leave time for the public to dis-convergence during filming will be recons- red. If the production teams are not sup- the depths he wants. The streographer cover and enter into the depth of the ima-tructed in front of the screen: popping-out ported by competent people in this way, translates these choices using the tools ge. In the same way, wide compositionseffect (negative parallax). they risk having their possibilities limited at his disposal, tools which he will super- with framing using high-angle or low-an- as to the creation of emotions in the viewer vise in their practical use. Given this, he gle shots favor 3-D effects and intensify specifically tied to 3-D effects of depth or is responsible for the adjustment of the sensations of dizziness. Geometric forms, of popping out, or even in certain cases, to angulation and the inter-axial distance buildings for example, are more quic- provoke visual discomfort in the public. between the center of the camera lenses kly identified by our brain and contribute according to the chosen focal length, and to the quick immersion into 3-D. As for
20 21Ensuring the continuity of the modulation of the each other on more or less sophisticatedstereoscopic range during a whole film mechanical or motorized rigs. The advantageIt is indispensable to think of a 3Ds film or of this arrangement is that it is often moreTV program in its entire continuity. For ci- rigid and avoids the aberrations linked to thenema in 3Ds, like in 2-D, the order of se- mirror set up.quences and shots at different steps in the Its inconvenience is that it imposes wide inter-making of a film are often modified, and axial distances which results in a “maquette” Binocleparticularly when it is being edited. effect tied to the apparent miniaturization ofThe modulation of the stereoscopic range the objects being filmed. It is not known howmay be modified by the inversion of shots to avoid this effect today, but it comes intoduring editing. For example, a close-up play from the moment one goes beyond the Two types of side-by-side rigswith much popping out will correspond ba- inter-axial distance of human vision. It can bedly with a wide landscape shot having a lot put up with, or even looked for, according toof depth: this alternation tires the viewer. how the director wants his production to be. shots in a fiction film. advantage of having its vertical camera placedIt is thus necessary to take care in the or- In any case, there is no other solution when Mirror rigs are used with steadicams, shoul- above the mirror, allowing the optical axis toganization of the shots to ensure smooth one films from far away, with objects in the be brought very close to the ground for ma- der-held cameras and most classic machi-transitions of depth for the public. foreground situated far from the camera king large vertical low-angle shots. nery. Mirror rigs are conceived or arranged in and one wishes to have 3-D. This is the case, two ways when they can be turned around the for example, for certain shots taken from a helicopter. optical axis: Integrated 3Ds camera -The first, called zenithal, favors the protection RIGS AND STEREOSCOPIC of the mirror. The vertical camera is placed Also appearing on the market are professio- nal video cameras that record two views of Semi-transparent mirror rigsCAMERAS The cameras are placed vertically at a 90° an- under the optical axis and directed upwards. the same scene through two optical axes in- This arrangement allows for a simpler protec- tegrated within the same camera body. ThisA gle to each other and find themselves in opti- tion from lights interfering with the mirror. “rig” is an adjustable support on which type of wholly integrated technology has cal concurrence in a semi-aluminized mirror. movie cameras can be arranged and -The second, called “crane position”, has the the advantage of limiting problems of dis- This mirror, also called a “beam splitter”, al- set up. There are two types according lows one camera to film through the mirrorto whether the cameras are placed side-by- and the other to film by reflection on the re-side or as a mirror (beam-splitter). It is the flecting side of it. Binocleneed to obtain or not a small or large inter- For this process, the transmission through,axial distance that determines the choice of a and the reflection from, the mirror is equalrig. If a large inter-axial distance is desired, to 50% each so that the loss of a diaphragm,usually for helicopter or distance shots, a si- induced for the camera filming through thede-by-side rig is used. mirror, is identical, or almost so, to the otherThe sophistication of side-by-side or mirror one. The mirror thus permits filming with anrigs is not linked to the device but to the inter-axial distance equal to 0 and thus bedefinition made by the manufacturer. Certain freed from the problems related to the spacemanufacturers make rigs that are versatile used by the cameras and lenses.and are simply assembled differently to be It is thus possible to reduce the inter-axialinstalled either as a side-by-side or mirror distance to 0 mm, which allows for the ca-rig. meras to be perfectly aligned. The mirror rig mainly permits small inter-axial distances,Side-by-side rigs indispensable for filming close to the sub-Two identical cameras are placed next to ject, which is the case in a large majority of Simplified schema of a semi-transparent rig
22 23 METHODS FOR ALIGNING AND DR SYNCHRONIZING 3Ds CAMERAS A stereoscopic shot requires paired equipment (cameras and lenses) andthe stereographer’s utmost attention to the adjustment of the rig during shooting.Not being able to have perfect alignment once the shooting starts, it is necessaryto continue working thanks to real-time correction algorithms for television, andin postproduction for cinema. It is a question of bringing to the viewer two imagesperfectly aligned vertically pixel by pixel.Factors provoking troublesome vertical disparities:- Difference in height of the optical axes (whether they are parallel or cross verti- Two examples of integrated 3-D camerascally)- Difference in the placement of one camera in relation to the other parity between the two stereoscopic points To this end, technical creation industries have- Difference, even minimal, between the focal lengths of the cameras and the of view to be superimposed, especially pro- seen, since the end of the 90’s, the rise offocusing of the lenses blems of alignment, differences in focusing, motion control rigs capable of being precisely- Different optical aberrations between the lenses of zooming, etc. However, the integrated paired electronically via a computer. More- Trapezoid effect resultant in vergence on the object. 3Ds camera has the drawback of generally recently, 3Ds image analysis instruments It’s a question of minimizing as much as possible these disparities when offering only a single setting for the inter- have arrived with, notably, the possibilityfilming. On a side-by-side rig, the optical axes are placed in parallel aiming at axial distance and a limited adjustment of of making a precise real-time drawinginfinity, and a test card is used at 3 meters to verify that the altitudes have been vergence. These restrictions result in heavy out of problems of disparity between tworespected. On a mirror rig, the same procedure is used in placing the inter-axial constraints when filming a close-up scene in stereoscopic images and correcting them indistances at 0. In both cases, test cards and a 3Ds monitor is used to precisely 3-D, and, more generally, does not allow for real time.adjust the alignment, if possible to the size of a pixel. complete control of stereoscopic production All these factors make it so that today one Likewise, that the colorimetry and luminosity of the cameras are identical through adjustment of the two parameters sees hardware and software solutions appearshould be watched over closely. Certain tools on the 3Ds monitor allow this to be inter-axial distance and vergence. from several components manufacturersprecisely monitored. for processing 3Ds shots in real time,Synchronization of the camera sensors at the pixel level is indispensable. The non- Progress of 3Ds rigs and monitoring of disparities which allows certain corrections—such asrespect of this rule on moving images leads to visual fatigue by the viewer. Whatever the talent of the stereographer, vertical disparities, detection of rotation and For the timecode, the cameras must be connected with one camera as TC involuntary disparities between the two trapezoid deformation—to be automated.“master” and the other as “slave”. viewpoints of the cameras remain. It is Certain software also permits automation As to scanning, putting one camera in Genlock master and the other indispensable to correct them when filming of the inter-axial distance and convergence.in Genlock slave is not precise enough, except for certain miniature cameras or live. For fiction, these defaults can also be Solutions of this kind, conceived in France orcameras conceived for this purpose. It is preferable therefore to have recourse to an corrected on the film site so that rushes can elsewhere, which allow these problems toexternal synchronization camera body in Tri-level Sync, connected to the camera be viewed comfortably. In postproduction, be corrected or parameters to be monitoredGenlock inputs. if these defaults are very minor and do in real time, are already being used on film Cameras without the Genlock input, such as digital photo cameras, are not bother the editing process, certain sites, particularly in live sports productions.problematic. Certain 3Ds monitors allow, however, scanning to be viewed and to stereographers prefer to usefully make these 3-D correctors are also being integratedtry “manual” or “on the fly” synchronization by triggering the cameras simulta- corrections during the “3-D calibration” into visualization tools used in fiction orneously. But this does not provide the indispensable guarantees need for a feature stage. This consists in adjusting the 3-D for capturing in order to judge the effectsfilm project or for live television. values for a shot or between two shots. It obtained without mental strain for the team. ensures the consistency of the 3-D effect for the length of the film.
24 25 LIVE MULTI-CAMERA 3Ds A modification of workflow should be consi- As a general rule, it should be noted that all 3Ds POSTPRODUCTION: dered in the 3Ds production unit. In fact, each the actors who intervene in the live streamCAPTURING stereoscopic source should undergo 3-D cor- should have 3Ds visualization: slow motion CORRECTIONS AND WORKFLOW rection before being integrated into the grid operators, synthesizer operators, special ef- ALive multi-camera 3Ds capturing implies ac- or the mixer. This correction can be multiple fects technicians, etc. ccomplishing postproduction in 3Dstions in real time in order to preserve 3-D ho- and specific to each rig. It encompasses the is not very different from traditionalmogeneity. The first action consists in analy- flip image in the case of a mirror rig, geo- The difficulty of live 3Ds multi-cameras today postproduction, if only that it is neces-zing new actors and organizing them into the metric correction, compensation for opti- is not only related to technical problems, but sary to manage file volumes twice as large.production team’s hierarchy. The director is cal centering, etc. Whatever the nature and also to the calling into question of the pro- It is also necessary to ensure the continuitythe one who conceives the stereoscopy of a number of corrections applied, they should duction. It is quite clear that the acceptance of depth in 3Ds scenes, by watching over theproject that puts the stereographer and all be done in a very short time since this period of 3-D is directly dependent on the quality of sequence of their stereoscopic ranges andthe technicians to work. comes before mixing. Today, this processing the stereoscopy, but it is also necessary to by correcting the disparities between the leftA single stereographer guarantees the qua- time varies from 40 to 120 ms. provide the necessary information for a good and right images. When filming fiction, theselity of 3-D capturing. He works in concert The quality and number of 3Ds visualizations narrative. Due to this fact, live broadcasting defaults can also be corrected, of course,with the director of photography. He is assis- is a key element of a 3Ds production tool. is a dangerous exercise in 3Ds. For example, before reaching the postproduction stage.ted by the convergence operators who are in Two cases are possible for the production: to if one wishes to bring information captured However, if these defaults are very minorcharge of the stereoscopy of one or two axes. propose a multiviewer which includes all the by a 2-D camera into a 3Ds stream, one can and do not interfere with editing, certainHe continuously regulates the inter-axial sources as well as the program and preview resort to a real-time 2-D/3-D transfer, or if stereographers prefer to make these adjust-distance and vergence according to the va- in 3Ds. This requires a certain vigilance in or- one wishes to provide a score or a time, one ments during 3-D calibration, or, in any case,riations of frame, focal length and focus. der to exclude from the mosaic any camera would proceed by inserting 3Ds elements these 3-D adjustments are reviewed in termsBy analogy with photography, it is necessary being adjusted. The second option consists into a 3Ds image. These techniques are to- of consistency over the length of the film.to integrate this team into the live production of keeping the sources in 2-D visualization lerable for the viewer as long as they areunit in order to make discussion easy and and to put only the program and preview in mastered. 3Ds. Viewing is at the heart of the process of 3Ds editingguarantee a consistent program. The postproduction of 3-D images requires
26 27 OPTIMIZING LIVE 3Ds COSTS IS POSSIBLE ! ting tools, this is rarely the case. copyright : Technicolor For this reason, during “offline” editing of 3Ds films or programs, it is imperative to Concerning the additional costs related to 3Ds capturing, the figure of 25 to 30%more than view 3Ds edited shots and to validate them 2-D capturing is often put forward, but according to those in charge of AMP VISUAL TV these regularly on a stereoscopic screen having figures are relative. The additional costs greatly depend on the length of the capturing itself, a size near to the one that will be used for and AMP VISUAL TV hopes to have, in the end, enough production streams in 3Ds to be able the final showing. In this way it is possible to identify at once the visual discomfort resul- to have economies of scale. What is most important today is to find methods for reducing the ting from the non-corrected stereoscopic installation and preparation times. If it is possible, for example, to have two cameras/lenses disparities or the different 3-D values used used only for 3Ds capturing, it would then be possible to considerably reduce the preparation in different shots. Example of correcting geometric time before shooting. But for this to happen, it would be necessary to have a greater volume of If possible, it is even desirable that the conti- disparities production than there is today. nuity of the shots be studied during the pre- paration phase of filming in order to make the 3-D space consistent before and aftera return to more rigorous methods of work after editing, during or just before the stage the transition by reducing to the maximumthan before, and to a more precise definition of calibrating the 3-D of the film. It is done by the differences in distance and convergenceof each person’s task, from preparation of a stereograph technician having experience of the cameras. Nevertheless, adjustmentsfilming to postproduction. These precau- with the correction tools, under the direction are often to be planned in postproductiontions, taken before the various operations, of the stereographer who has already wor- through horizontal transfer of the left and Flare: a source of visual discomfortlimit the alternation of inconsistent 3-D se- ked on it during filming. right images.quences. The change in location of the space to whe-However, even if a stereographer has per- Continuity of shots during editing of 3Ds images re the viewer is attracted, from one shot tofectly adjusted the rigs and taken care to stereoscopic range at the end of the prece- The rhythm of shots edited in stereoscopy another, can also cause visual discomfort.limit the “bad” connections between shots, ding plan consistent with the beginning of is logically slower than that of editing of 2-D Thus the necessity of an appropriate scriptthe editor, will in all likelihood, as in the case the next one. images, for when there is a change of shot, it and a specific “3-D calibration”, making theof 2-D, change the editing order that was is necessary for the brain to have one secondplanned at the beginning. Due to this fact, to appreciate the new universe to be explo-it will be necessary to again verify the conti- red. Learning to watch 3-D by the viewer Adapting convergence and editing:nuity between shots during each viewing of can, however, reduce the accommodation 3-D continuity between two shotsthe 3Ds already-edited rushes. time necessary for each change of shot. ButFurthermore, following the planned post- as of today this is only a supposition. In 3Ds, convergence between two successive shots must be adjusted. Usually, the convergence shotsproduction method and the production bud- In order to limit mental discomfort and re-get, it might be useful to take some time to will be brought closer during cropping in postproduction if they are too different. Otherwise, the duce adaptation time between each shot,correct the involuntary disparities between it is also possible to use the “3-D dissolve” viewer may feel visual discomfort. The time this adjustment takes can also vary. Experiences thatimages. This would mean to correct the- method which smoothes the passage from took place during the production of Legend of the Guardians: The Owls of Ga’Hoole (2010) broughtse geometric and colorimetric disparities one 3-D shot to another when the 3-D ef- to light the fact that the softest transition in 3Ds is obtained when the vergence of entrances into abetween the left and right images such that fects are obviously too different.each of the homologous pixels is situated at shot is progressively adjusted according to the previous shot. In this film, the length of the vergence Because of these constraints, it would bethe same altitude. It must be kept in mind more practical in the absolute for stereos- adaptation time between shots varied from one sequence to another from 8 to 40 images. Further-that these corrections, necessarily made for copic editing to take place “online”, directly more, rather than making the depth characteristics of each shot exactly correspond to the level ofa live capture, should become a postproduc- from already-corrected stereoscopic ima- the cropping point, it was noticed that for most of the sequences, it was possible to eliminate onlytion operation for fiction. ges. However, for reasons of visual fatigue 50% of the difference in depth between shots, and to leave a slight upsurge in 3Ds when cropping.This operation could be made on the rushes over time, but also for the sake of economybefore editing, but today it is generally done Of course, nothing prevents one from using a brutal 3Ds connection between shots to provoke a and/or the non-availability of online 3Ds edi- particular sensation in the viewer.