Part1 Previs Postvis Techvis
Previs, postvis and techvis allow directors to visually test things out in their film and help producers figure out the optimal way to go about shooting the film in a more cost-effective way.
Previs is actually a simple production of the shooting content before the official shooting. It uses low mode and simple animation to show the actor’s position, framing, camera angle, camera movement and other major directions, which can be used as a reference for directors, camera directors and others when shooting. As we’ve touched on before, previs involves previsualizing part or all of a film. Often used for particularly complex scenes, it uses storyboarding, animatics and asset building to create a three dimensional visualization of the story’s world, enabling the director to explore different shots and angles. In the past, filmmakers used to plan their visual presentation with the help of sub mirrors, concept maps, solid models and props. Now the previs team can complete and accelerate this process through computer animation tools.
Previs enables a director to visually see the story before going to camera, which may sound like a novelty to some, but when we are planning something either technically or practically challenging, it helps immensely to see how things play out beforehand. Anything dangerous or expensive that we may only get one chance at shooting, for instance, might be something you want to invest some previs time into. Previs enables us to encounter some of these problems and plan for their resolution. Beyond that, previs plays a major role in storytelling since directors can play with lighting, cameras, and sets before production to help them discover how to tell the story the way they want to.
Postvis is to integrate the previs assets into the real shooting materials to see the visual effects in advance. Postvis has to decide where the live camera is. Postvis producers need to understand the size of the set and match the material with the 3D virtual scene. Postvis usually uses complex 3D tracking programs to simulate the motion of a real camera. Postvis greatly helps the editorial process by allowing directors and editors to cut with missing bits of the shots incorporated. A postvis team can quickly take elements of shots and insert missing backgrounds, creatures, and effects – any number of details the director needs. Turning the material over quickly affords the production time to refine the edit and enact changes to make the best of the material.
Previs and postvis provide the possibility of preview and determine whether some actions are feasible without the need to complete the final visual effect production. In fact, many elements of the sequence will be modified in this link. Aside from the creative key benefits, previs is cost-effective in that it reduces guesswork on the days of the shoots. Previs can really help the actors know what is happening scene by scene when shooting against blue.
The role of techvis is equivalent to the technical part of previs. At this stage, we need to work closely with all the creators of the crew, from the art director to the director, to help them plan their shots. This is to build the scene, visual effects may be involved in the process of the production of visualization. Techvis isn’t some other thing that we do – it’s at the core of our production-centric approach to visualization. And because of that approach, we end up spending a good deal of time on set, working closely with the camera and visual effects departments. It’s common to reverse engineer some shots for acquisition on a greenscreen stage when the actor is suspended by cables or by various stunt rigs. Some shots need to be laid out showing a clear demarcation between digital and practical elements or extensions. Motion–based shots generally require techvis in order to verify the legality of the movement well ahead of the shoot day.
Part 2 Film Animation / VFX Animation / Game Animation
Film animation is closer to reality and more life-oriented. So the action of life is also a special requirement for the quality of animation production personnel. One of the most important qualities an animator must possess is whether the action of a character can be natural and fluent, and whether it conforms to the logic of life. In the animation, we should not only design a large number of language and expression actions for the characters, but also promote the development of the story plot of the film through these actions, combined with the sound and lens design. Moreover, a large number of detailed actions should be designed to help improve the credibility of the role and portray the character. It can be seen that the purpose of film and television animation is mainly for narrative performance and character shaping. According to the needs, the producers can use a variety of methods and angles to express each plot.
The controllable actions in the game animation are all circular actions. Walking cycle, running cycle, after walking and running, we have to connect other cycle actions, and there are corresponding cycle connection actions between each cycle action. A character’s boxing attack has gone through stand-by, preparation, boxing, boxing back to stand-by, which is a cycle. In the game animation, the role is fixed in a few actions and repeated constantly. For the purpose of the game experience, the action of the game role is actually made according to the intention of the software writer. Many of the requirements of the movement itself does not conform to the normal law of movement. Obviously, the purpose of game character animation is to bring players a specific game experience.
VFX animation refer to a special effect that we usually watch movies and other videos. The special effects here point to two points: modeling special effects, special effects modeling, that is to say, green screen shooting, post color matching, special effects scenes, etc. VFX animation are mainly to make up, process and perfect the visual effect of the screen by combining the false pictures taken by the green screen in the early stage and the computer special effects in the later stage. In VFX animation, in order to make the information dissemination more accurate, the picture quality more exquisite, or in order to make an object that does not exist in the nature as the theme to promote the plot development, we need to make very realistic or visual elements with visual impact, and the creation of such elements, the VFX animation play an irreplaceable role.
Film and television animation is more extensive in special effects and animation performance. It covers a wider range and has more diversity. Because of its particularity, game animation must find a balance between the expressiveness and the size of the game file. And film and television animation is completely free from these restrictions. In this respect, there are some differences between 3D games and 3D animation, and between 2D games and 2D animation. In the two-dimensional film and television animation, although track animation is often used, but plays a decisive role and can leave a deep impression on the audience, often those with beautiful composition, creative perspective and strong coherence.Creating animations for film and games and VFX are three different processes. While a film and vfx animation are meant to be viewed, games animation are all about user interaction.
Part 3 Motion Capture with Matchmove and Rotomation
In visual effects, matchmove is a technique that allows the insertion of computer graphics into live-action footage with correct position, scale, orientation, and motion relative to the photographed objects in the shot. The term is used loosely to describe several different methods of extracting camera motion information from a motion picture. Sometimes referred to as motion tracking or camera solving, matchmove is related to rotoscoping and photogrammetry. Match moving is typically a software-based technology, applied after the fact to normal footage recorded in uncontrolled environments with an ordinary camera.
Rotomation is a technique of animating a 3D element on top of the tracked motion picture footage, frame by frame to match an actor or an object in a live-action plate. To replace specific and complex deformation objects, such as characters, rotomation is needed. Rotomation is mainly used for digital replacement of characters, including erasure like steel wire, original characters and other elements and role performance tracking. In addition to replacing actors, rotomation is also often used in digital makeup.
Motion Capture is the ability to track in 3D the motion of a non-rigid object, like a human body or face or a piece of cloth. This is a special case compared to rigid moving objects or standard matchmoving, because, for each frame of the footage, the position of any non-rigid track is totally independent from any other previous position, or any other track. Therefore, its 3D position cannot be computed from a single view. To be able to compute the depth of such a track, you must see it through at last two different viewpoints.
Matchmove artists match CG scenes with shots from live-action footage so the two can be convincingly combined. They recreate live-action backgrounds on a computer in a way that mirrors the camera on the set in every way, including lens distortion. They do this by tracking the camera movements to make sure the real and virtual scenes appear from the same perspective. Sometimes matchmove artists go to the film set to take measurements and put up tracking markers. Then they use these markers to track the camera movement and work out the relevant coordinates in the 3D scene. They do this using 3D tracking programs like Maya or 3DEqualizer. Matchmove artists also do body and object tracking, using markers to recreate the movements of people, vehicles or other objects in CG. The motion files created with motion capture are then passed on to other departments via the VFX pipeline, so that, eventually, they can be seamlessly combined by the compositor.
Rotomation can be a complicated procedure, and just like other VFX techniques, its successful completion can take a significant amount of time and human involvement which can be combined with the motion capture. A rotomation procedure can vary greatly, depending on the needs of the scene. But generally, a procedure done well is based upon the assumption that the camera has been correctly matchmoved and fit into the set. One of the first tasks to do in this procedure is to establish the distance to the element you are rotomating and the camera. Other tasks following this chain procedure, which include among others, setting the initial pose, using non-linear animation techniques, analyzing the movement, and model editing.