Visual Effects (abbreviated VFX) is the processes by which imagery is created or manipulated outside the context of a live action shot in film making.
Visual effects involve in the integration of live-action footage and generated imagery to create environments which look realistic, but would be dangerous, expensive, impractical, or impossible to capture on film. Visual effects using computer-generated imagery have recently become accessible to the independent filmmaker with the introduction of affordable and easy-to-use animation and compositing software.
Visual effects are often integral to a movie’s story and appeal. Although most visual effects work is completed during post-production, it usually must be carefully planned and choreographed in pre-production and production. Visual effects primarily executed in Post-Production with the use of multiple tools and technologies such as graphic design, modeling, animation and similar software, while special effects such as explosions and car chases are made on set. A visual effects supervisor is usually involved with the production from an early stage to work closely with production and the film’s director design, guide and lead the teams required to achieve the desired effects.
Visual effects may be divided into at least four categories:
# Matte paintings and stills: digital or traditional paintings or photographs which serve as background plates for 3D characters, particle effects, digital sets, backgrounds.
# Digital effects (commonly shortened to digital FX or FX) are the various processes by which imagery is created or manipulated with or from photographic assets. Digital effects often involve the integration of still photography and computer-generated imagery (CGI) to create environments which look realistic but would be dangerous, costly, or impossible to capture in camera. FX is usually associated with the still photography world in contrast to visual effects which is associated with motion film production.
# Another branch of visual effects is called Motion Capture or Mo-Cap for short. It’s the process of recording the movements of objects and or people. In a session of motion capture, the subject whose motion is being captured is recorded and sampled many times per second by different scanners placed all over the environment. There are different types of systems that read the actor’s movement. One of which is the optical method that uses tracking cameras that lock onto specialized markers placed over the actor’s motion capture suit.
# The other type of method is called the non-optical method where instead of capturing the markers location in space, it recorders and measures the inertia and mechanical motion in the area. This type of motion capture doesn’t just apply to the body, but can used to track the facial movements and expressions of an actor and transfer them to a 3d model later on in the pipeline. The same type of concept of using markers to track motion is used, but more often than not, the actor’s face will have painted dots on their face rather than ball shaped markers. Not only is the actor’s movements recorded in this process, but the movement of the camera is also recorded, which allows editors to use this data to enhance the environment the motion captured set is imagined in. Once all of this is captured, the motion captured data is mapped to a virtual skeleton using software such as Autodesk’s MotionBuilder or other software of choice.
So basically, anything that’s difficult to film then visual effects is used to achieve it. For example, aliens attacking the earth is impossible to film so visual effects is used for all the alien creatures to destroy the city. This is a very obviously example of visual effects. A lot of time visual effects id used in more subtle areas. For example, if there’s a scene in the story that needs to be in another country, an imaginary location or a city in the future/past. It’s just inefficiency to go to another country or build a set. Visual effects in these situation are really helpful.