Alpha Channel (or Alpha Pass)

A computer image file contains color information, RGB (or red, green, & blue), and an alpha channel. The alpha channel contains compositing information such as the degree of transparency. The alpha pass is a black and white rendering wherein the object to be composited appears as white against a black background. If it is solid white, the object will cover the background image in the final composite. If it is semi-transparent, it will composite as semi-transparent in the final composite (with the background showing through).

A rough animated preview of a scene. If a sketch is a test for a painting, an animatic is a test for a scene; even the objects being animated are only rough approximations of the final models. An animatic can be thought of as a moving storyboard.

Aspect Ratio
The ratio of the width of an image to its height. An aspect ratio of 2:1 would produce an image twice as wide as it is high. Television has an aspect ratio of 1.33:1. Panavision is 2.35:1.

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Background Plate (or Element or Image)

The image or series of images over which another image is to be composited. A typical example would be the stars in a space movie. The stars are filmed (or created), then those images are used as a background for the spaceships.

Bitmap Image
An image which is created by assigning color and brightness information to each pixel.

Blue Screen/Green Screen
A blue (primary blue) backing against which an actor or object is photographed. This exposes only the blue layer of the film emulsion (in that area), making it easy to separate the actor for future compositing. Green is used most often when the element being filmed is a person: green is easier to remove without affecting the flesh tones of the actor.

Bump Map
A texture applied to a surface in CGI which gives the appearance of a dimensional surface. It does not actually alter the geometry of the object, it merely gives the appearance of doing so. For example a bump map or ripples applied to a flat plane will look like 3D ripples when viewed from above, but when viewed from the edge of the plane, the plane will still be flat.

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A computer animation term that refers to an object or other item which is attached to another object (the "parent") and inherits its motion from it. If you pick up a ball, the ball becomes a child of your hand. See also "Hierarchy" and "Parent."

Color Balance
When the color from all elements in a shot match so they look like they were photographed as one. Care must be taken to use the same color lighting for all of the elements. For example, if the background plate is that of a setting sun and you are compositing in an actor in the foreground, the hue of that foreground plate should match the warm yellowish colors of the background.

Color Channel
Each of the red, green, blue, and alpha components that make up the color, brightness and degree of transparency of a pixel.

Color Depth (or Bit Depth)
The number of possible colors available for rendering or viewing. Color depth is determined by the number of bits allotted to each pixel, and the more bits, the more colors will be available. 4 bit has 16 colors; 8 bit has 256 colors; 16 bit has 65,000 colors; 24 bit has 16.7 million colors; 32 bit has 16.7 million colors and an alpha channel with 256 shades of gray. Color depths can also be thought of as the number of bits per channel instead of all together. For example, Cineon is 10 bits per channel. SGI RGB is 8 bits per channel, for a total of 32 bits. So in this last example, there are 256 shades of red, 256 shades of green, 256 shades of blue, and 256 levels of gray in the alpha channel.

A composite is a merging of two or more images (elements) into one final image, or the act of doing that. For example, you may have footage of an actor, footage of an alien planet surface, and footage of a spaceship. These will all be layered (composited) onto each other so in the final version (the composite) you will see the actor standing on the alien planet with a spaceship in the background. In the days when this sort of thing was done on film in an optical printer it was commonly referred to as "superimposing".

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Depth of Field

The range of focus around a subject. For example, the actor is in focus, but the sign in the back of the store is out of focus. Or the phone in the foreground is out of focus but the actor in the background is in focus; when the phone rings, the focus is adjusted to bring it into focus, throwing the actor out of focus. In photography, Depth of Field is a function of lens focal length and aperture (F-Stop).

Digitize (3D)
To bring a 3D object into digital form. There are essentially two methods for doing this: a laser digitizer, which uses a laser to scan the object and generate data, or a digitizing pen system. The pen system uses an special pen whose position on a digitizing tablet is tracked by the computer using magnetic field disturbances.

Displacement Mapping
Displacement mapping is similar to bump mapping except for one key difference, which is that it actually distorts the geometry. A plane with a rippling displacement map will actually appear rippled when viewed from the top or the side. The drawback is that it will only displace an object from its points, so to achieve a nicely displace surface requires many polygons (and therefore, points). A flat plane made up of one polygon will not look rippled because the only points available to move are the four at the edges. However, a flat plane made up of a thousand polygons can easily be rippled.

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Ease In/Ease Out

An animation term describing the characteristics of stopping and starting. When a person moves their arm, the arm actually "eases" into the move (overcoming inertia) rather than just jumping into the move like a robot’s. Likewise, when the arm stops, it "eases out" rather than just abruptly stopping. Generally, a move starts out slowly, then speeds up to normal speed, then slows down to stop. This easing in and easing out is usually very subtle.

An image, or series of images, which is to be combined with others. For example, a person against a blue screen, a miniature set, and an explosion. These elements, all filmed separately, will later be composited.

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One half of a video image. Televisions display their images by scanning the image onto the screen using two fields for every image, each time scanning every other line (525 horizontal lines total). Computer monitors scan both fields at once, progressively- -from top to bottom- -which is why they appear to be flicker free.

Film Recorder
A device that transfers computer images to film. The process is generally called a "film out" or "filming out".

Film Scanner
A scanner that brings the images on movie film into the computer.

Generally, a term used for a shot when it will have no more work or adjustments made other than maybe preparing it for the final filmout. There are different types of "final" though. There is the type mentioned above, and there is "motion final" which is when the animation is locked and will not be changed, and "camera move final" when the animation for the camera is locked, to name just two types.

Forced Perspective
A technique used with miniatures or full sized sets (and sometimes even CGI), which causes the apparent depth to be artificially exaggerated. This is done by taking advantage of film’s 2D nature by cheating-- building smaller and smaller as the distance from the camera increases. Smaller things will look farther away than they actually are.

Loosely refers to an element of a shot which appears closer to the camera. In compositing, it refers to the element to be placed on top of the others. The text at the bottom of the screen which says "Five years later. . .…" is a foreground element.

Frame Grab
A single image captured from a video or film source onto a computer.

Frame Rate
The rate at which the film/video is shot or will be played back. Normal speed for film is 24 frames per second. Normal video (in North America) is 30 frames per second (actually 60 fields per second).

Front Projection
A compositing process whereby film is projected onto a "front projection screen" which the actors stand in front of. The screen is highly reflective (it is made of the same material as road signs). The image is projected right over the actors, but since they are not very reflective, and since they are lit with film lights which overpower the projection on them, it is not seen on them.

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Garbage Matte

A matte which conceals unwanted imagery included in the original photography. For example, the rig holding up a model. Garbage mattes are also used when the blue screen doesn’t fill the whole frame. (See "Matte")

The number of times an image has been duplicated. The original negative is the first generation. A duplicate negative is a second generation. Digital images do not degrade when copied digitally: an image can be copied from computer to computer with no quality loss. Once it’s on film, of course, a copy of that film would be of lower quality.

Along with mesh, model, and object, this refers to the things you create with points and polygons in a modeling program.  Of course, it's also a type of math, but in 3D graphics, it's more often used in terms of objects.

There are two kinds of grading: in-grade and out-grade. To in-grade means to take the image data (from scanned film) and convert it from the 16 bit Cineon format to an 8 bit format (such as SGI RGB), adjusting the color to match a sample "wedge" of the actual printed film. Out-grading is the reverse: putting the image into 16 bit Cineon format so it can be recorded out to film.

Green Screen
See "Blue Screen".

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Hanging Miniature

An effect which uses a model, such as a spaceship, which is placed directly in front of the camera so as to appear big compared to the actors who are farther away. Also called a "foreground miniature".

A computer animation term that refers to a group of objects or other items that are set up in parent/child relationships. For example, the bones in your body are a hierarchy. Your head is a child object of your neck; your hands are children of your forearms, which are children of your upper arms, etc. See also "Child" and "Parent."

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Image Map

Placing an image over a 3D object in the computer. Image maps can be bump maps, color maps, diffusion maps, specular maps, etc. For example, an image of a grid used as a bump map would look like metal plates on a ship, and an image with numbers used as a color map would put the identification numbers on it.

Interactive Light
Light which interacts with an object in 3D. For example, an actor has a flashlight and aims it at the computer generated ship, where the light can be seen playing on its surface. Or the reverse: the computer generated ship has flashing lights on it which need to be represented on the set when the actor is filmed so he’ll end up being lit by the ship.

Inverse Kinematics (or IK)
A method of setting up character animation wherein the animator can move the end of a chain of bones or objects and the rest will follow. For example, grab the hand and pull it up and the rest of the arm will follow, anchored at the shoulder as in real life. In "forward kinematics", to raise the hand, the animator would first position the upper arm, then the forearm, then the hand.

Generally used in CGI in the same way that "take" is used on a movie set. Doing another iteration would be doing another version, presumably with some requested changes. Used interchangeably with "version" and "take".


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     1. An electronic method of compositing one element onto another. 
     2. The main light in a scene. 3. Short for "keyframe" (see below).

In animation, a position setting for a character or object. For example, a if a character is to raise his hand into the air, a keyframe is set on frame 1 with his hand at his side, then the hand is raised to its next position, in the air, and a keyframe is set for frame 15. The computer will then move the hand over the course of the frames between 1 and 15 from his side to up in the air.

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Live Action Plate (or Live Action Element)

A shot using actors, as opposed to animation. Shot live on a set, not an effect.

Lock Off
A shot wherein the camera does not move or rotate at all.

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Match Move

To use a computer to recreate the camera move from a live action plate so a 3D element can be added. This can be accomplished by hand or with software.

An opaque (or semi-opaque) image that is used to keep an area of film from being exposed. The film equivalent to the alpha channel of a digital image.

Matte Line
The visible lines that can appear around an actor or object if it has been improperly matted (composited) into a shot.

Matte Painting
A painting, traditionally on glass, but now more often done on computer, which adds to or replaces part of a live action image. An example is the throne room scene at the end of Star Wars, where only the soldiers along the aisle are real and the rest are part of a painting. There are actually two kinds of matte painting; the standard 2D kind as mentioned above, and a newer version that uses some 3D elements as well.

Mechanical Effects
Special effects that are done "live" on the set during principal photography, not added in later. They differ from the similar "practical effects" in that they are, naturally, of a mechanical nature (robots, automatic doors, etc.).

Along with geometry, model, and object, this refers to the things you create with points and polygons in a modeling program.

As a verb it means to create something, usually in a modeling program.  (Example:  I am going to model a dinosaur.)  As a noun, and along with mesh, model, and object, this refers to the things you create with points and polygons in a modeling program.  (Example: I just made a dinosaur model.)

An effect where one image is transformed into another by changing its shape and color. Terminator 2 made this effect famous.

Motion Control
A computer controlled camera system which can repeat moves over and over again with exact precision. The camera moves on tracks. It was fully developed in the 70’s for use with miniature photography, but has since expanded to be used for live action composites.

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NTSC Standard

The video broadcast standard in the North America. It is 525 horizontal lines of resolution displayed in two fields at 60 fields per second.  To be avoided at all cost.

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As a noun, along with mesh, model, and geometry, this refers to the things you create with points and polygons in a modeling program.  As a verb it's what you should do when someone asks you to work for free.

Open GL
A computer display method that allows for objects to be seen as solids rather than wireframes yet still be manipulated in real-time.

Optical Printer
A machine made up of one or more projectors and a camera. It is used to combine separately photographed images onto one piece of film. Invented in the 1920’s and fully developed in the 1930’s, this is still the basic idea behind all compositing, including digital compositing.

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A computer animation term meaning that a particular object has other objects attached to it that will move along with it. The objects that are attached are called "children", and the whole setup is called a hierarchy. See also "Child/Children" and "Hierarchy."

Particle System
A computer application which generates and animates particulate matter, such as rain, snow, sparks, explosions, flames, bubbles, etc. The motion of these particles can also be used to drive full animations. For example, you can set up a particle system to have particles disperse over a terrain object, then "attach" animated spider objects to those particles so the spiders will now walk along the path of those particles.

Pin Registered (or Pin Reg)
A camera, projector, or film scanner which uses pins pushed into the sprocket holes while the shutter is open to insure that the film is perfectly steady is "pin registered."

Literally, picture element (using "pix" as short for "picture"). The smallest part of a digital image. A pixel is one tiny dot, similar to the dots which make up newspaper images except that they are square not round, and there is no empty space in between them. A standard pixel resolution for film, for example, is 2048 pixels wide and 1556 pixels high. Television resolution is roughly 720x486 pixels.

An image element. There are background plates, blue screen plates, foreground plates, live action plates, etc.

An "add on" computer program which is run from within, and augments, another computer program.

Digital objects are made of polygons. A polygon is a flat surface area connecting a group of points (or "control vertices" or "CVs"). You can think of this page of paper as being four points, one at each corner, connected by the paper, which would be a polygon. Since polygons are flat, to make a curved surface a large number of small polygons is needed. To think of this in a 2D way, imagine a stop sign. It doesn’t look round because it only has 8 sides, but if it had, say, 60 sides, then from a certain distance it would look round because you wouldn’t see the individual sides. Now, back to 3D, think of a soccer ball; each of the different colored panels would be one polygon (except that in a real soccer ball the panels are curved so imagine they aren’t). Shrink the panels in half but double the amount of them and the ball stays the same size but looks rounder. A book could be modeled out of polygons and look good with only 200 of them, whereas the Titanic model for the film had over 2.5 million polygons. "Polys" is often used as the plural form of polygons.

Practical Effects
Similar to Mechanical Effects. Effects which are done live on the set (explosions, lightning, etc.). Often an effects shot will be a combination of practical and digital. For example the window of a car shattering will be done as a practical effect on the set with actors or stuntmen in the car, but the monster’s hand hitting it will be done digitally.

Procedural Texture
A computer generated surfacing technique whereby an algorithm is applied to a surface to give it a certain appearance. For example, there are procedural textures of wood and marble. These do not rely on image maps, they are completely computer generated based on certain user definable parameters, such as grain size, color, etc. One advantage of procedurals over image maps is that they use less ram. A disadvantage is that they can take longer to render because the computer must calculate their parameters.

Pull a Matte
The current CGI use of this term is: to create a matte (or alpha) from an image for which there is none.

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A computer animation rendering method where an animation is rendered with only basic color information and no image maps or lighting effects. Quickshade is usually used for rendering animatics.

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Rear Projection

An in-camera method of compositing where (typically) an actor is placed in front of a translucent screen and an image is projected onto the screen from behind. This can be seen in just about any old movie where actors are in a car; the road behind them is usually rear projected,

To output digital images to film. Recording is, of course, the opposite of "scanning."

The process by which the computer computes and generates the final image(s) based on all the input and parameters set by the artist. Somewhat akin to what happens when the director yells "action" on a movie set: all the setting up, rehearsing, lighting, etc. is recorded (rendered to film). Or it can be thought of like paint-by-numbers, wherein the artist assigns the color numbers to everything in the image and the computer fills them all in (renders).

     1.  To trace the movement of something. In 2D, the image can literally be traced. In 3D, it is more a matter of matching the movement.

     2.  To remove unwanted portions of an image frame by frame. For example, an actor was filmed in front of a cloudy sky but you need it to be cloudless. You would rotoscope the actor, trace around him on every frame so he can be removed from that background and composited over a cloudless sky.

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Safe Action Area

The area near the edge of the frame which is not subject to the possibility of being cut off either in projection or on TV by misaligned equipment.

Safe Title Area
Similar to Safe Action Area, but it allows for even more space at the edges to be sure that no words are cut off.

The degree of color. Bright vivid colors are very saturated; pastels, less so.

The process of bringing two-dimensional images, or three-dimensional objects into the computer. A two-dimensional image can be scanned with a scanner or traced with a pen on a tablet or mouse. A three dimensional image can be digitized by laser scan or by a digitizing pen which uses magnetic fields to register the X, Y and Z coordinates.

Script Breakdown
A list of shots based on an analysis of the script. It contains information such as Show Name, Shot Number, Scene Number, Scene Description, estimated time to complete each shot, estimated costs, pre-production breakdown, etc.

Shot Card
A sheet containing all the information necessary for an artist to work on a shot. It contains information such as: Show Name, Shot Number, Scene Number, a copy of the storyboard for that shot, artist(s) assigned, due dates, scene setup information, data location, etc.

Split Screen
A composite technique where the screen is divided into segments that each have a different image. An example is in every TV show where a character meets his or her evil twin.

Stop Motion Animation
An effects technique where a model is filmed for one frame, moved, filmed again for one frame, moved again, etc. King Kong (the original) was stop motion, as was A Nightmare Before Christmas.

A drawing of the intended scene, looking somewhat like a comic. It illustrates the character action, the camera movement, etc.

To expose a piece of film more than once for the sake of compositing two or more images (without the use of mattes). The images will bleed through each other.

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Putting shots onto videotape to send to the director or producer etc. to show progress or get feedback.

A machine that transfers film to video, or the act of transferring film to video.

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Up Vector


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A direction.  For example "up vector" is the line that points up.  In 3D an "up vector" is often used in order to tell an item which direction is supposed to be up, in case it is rotated in such a way that its own Y (up) channel no long points up.

A film format wherein 35mm film is run through the camera horizontally. The image is 12 perfs wide. VistaVision is often used for photographing background plates in effects work because it allows full widescreen without anamorphic lenses.

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A wedge is a film sample. This can either be a sample of the original film, to show what the final should look like, or it can be a sample of an effect shot which has been filmed out to see if it matches the rest of the footage. When filming out, several test frames are done first with different printer light settings to check which will give the best results, then the full shot is printed out.

Weight Class Tool (or Weight Tool)
Weight Class Tool (or simply Weight Tool) is an object or collection of objects that produces static and/or dynamic weights for use with effects, shaders, and any other messiah entity that uses spacial weight values/maps.

Wire Removal
Removing visible support wires or harnesses from a shot using a computer.

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Y--- This space available.

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Z-Depth Pass

The Z-Depth pass is an image wherein distance from the camera is represented in terms of shades of black and white, white being closest to camera and black being farthest away. It is used, for example, when compositing images together and it is necessary to adjust the visibility for something that is a certain distance camera (like particles underwater), particularly when there is movement along Z (X is left/right, Y is up/down, and Z is front/back).

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