or VFX are the term given in which images or film frames are created and manipulated for film and video. Visual effects usually involve the integration of live-action footage with computer generated imagery or other elements (such as pyrotechnics or model work) in order to create environments or scenarios which look realistic, but would be dangerous, costly, or simply impossible to capture on film. They have become increasingly common in big-budget films, and have also recently become accessible to the amateur filmmaker with the introduction of affordable animation and compositing software.
Today, matte paintings are done with both paint and with computer generated visual effects. Rather than filmed through glass, the actors are filmed normally and later composted into the matte painting. If the actors are filmed on a partial movie set (without any green screen, etc.) then the effect is a matte painting... even if you use computer generated effects to get the effect.
Compositing is the process of combining various elements, such as 3D imagery, live action film footage and still imagery, to create a finished shot. All visual effects that include live actors will require compositing. As mentioned above, matte paintings are no longer painted onto glass. Rather the live action is composite with matte paintings using a compositing program such as Adobe after Effects or Apple's Shake.
Rotoscoping, or masking, is the basis of compositing. It is the process of drawing a mask around an element in a frame or sequence of frames. The resulting image is a combination of the Red, Green and Blue color channels in addition to an Alpha channel which defines transparency
3D Animation is animating computer generated objects that appear in a three-dimensional space. They can be rotated and moved like real objects. 3D animation is at the heart of games and virtual reality, but it may also be used in presentation graphics to add flair to the visuals.
3D animations including animated 3D models are a great way to bring to life an idea or design that is still on the drawing board or just difficult to describe with words. 3D animations can make visual that which is invisible or hard to conceive. See geometry calculations, VRML and surface modeling.
Computer Non-Linear Editing is not foolproof however. You must have the right combination of Ram, Hard Drive Space, and Operating System. Often times there are hardware and software conflicts with other elements within the computer, which can result in crashes. Outputting the finished video back to tape can have mixed results, such as jumpy or skipped frames. If you have a PC and don't have all the requirements to perform the entire editing process, you can still use you computer simply as an edit controller, titler, or sound mixer with the proper software. In fact, using a computer in a hybrid Linear Editing configuration is fairly standard in many professional and amateur editing suites.