An action is a mapping of time versus values (animation).
An Alias modeling window with three asterisks located on the window's title bar. Actions are performed based on the active window. A window may be made active by clicking the cursor in it.
A rule or procedure for solving a mathematical problem that frequently involves the repetition of an operation.
The name of the Alias|Wavefront software system for modeling, animation, painting and rendering, with connections to peripheral input and output devices. Also the name of the main menu level in that system.
An anchor is a bone acting as the root node for any bones beneath the anchor. See Inverse kinematics.
The process of creating and recording images that change over time. Though often interpreted as implying only two-dimensional image changes, it may be applied to any model or scene changes in three dimensions as well.
An animation parameter is an attribute of an item that can be animated. For example, X, Y, and Z Translation, Rotation, and Scale.
A group of methods for avoiding unwanted visual effects due to limited display resolution. These effects include staircasing along diagonal lines, moiré effects in checkerboards, and temporal aliasing (strobing) in animated scenes.
American Standard for Computer Information Interchange. Alphanumeric text interchange format readable by a number of machines and programs.
The ratio of width to height of a rectangular area, such as a window, viewport, pixel, or CRT.
Qualities or characteristics that affect the visual representation of surfaces, for example: color, reflectivity, transparency, and texture(s).
An axis is a straight line indicating the origin and direction. By using two axes, a plane is determined: for example, the XY plane is defined by placing the x and y axes so they intersect at the 0 point (origin). Three dimensions are determined by using three axes: X, Y, and Z.
A particularly smooth class of approximating splines. B-splines are fully approximating: such a curve generally passes through its control points only if several of them are in the same location. See also NURBS.
An image brought in to one or more modeling windows. Backdrops are not rendered. They are used for reference purposes when constructing models and scenes.
An image, color, color ramp, or environment rendered behind all objects in a scene.
A technique for creating a graphics display by describing it in terms of pixels.
A two-dimensional input device, consisting of a sensing surface (pad) and a pointing device (pen, mouse, or puck).
A blend curve is a normal NURBS curve with construction history.
A method of computing the shading of three-dimensional surfaces, developed by James Blinn. It uses four characteristics: Diffusion, Specularity, Eccentricity and Refractive Index.
A bone is the connection between each joint (rotation pivot point) in the skeleton. Bones are used to build skeletons for inverse kinematics animation.
A memory area in which information is stored for later retrieval.
A rendering technique that simulates bumpy surfaces. A technique for creating a surface texture on a three-dimensional object by wrapping a two-dimensional matrix of normals onto its surface. The matrix may or may not be random.
Computer Aided Industrial Design. The method of designing electrical and mechanical devices, components, and systems using computer systems. CAID typically makes extensive use of computer graphics.
A position from which a scene is viewed. A camera is described by a combination of its position, viewing direction, rotation, and field of view.
A chain is a number of bones between an anchor and an end-effector. A chain can be part of a dag hierarchy or an entire hierarchy.
A channel is a set of data that describes what values its animation parameter should assume at different frame times.
Characters represent an animated entity in the scene or interactive piece. A character's geometry is specified as a set specified in a stage.
An Alias AutoStudio tool to incorporate digitized data back into a 3D wireframe model.
To press and release the mouse button, once.
Removing the parts of the graphic image that are outside defined boundaries.
A cluster is an entity that logically groups an arbitrary list of CVs and dag nodes so that they can be transformed and manipulated. A cluster can be viewed as a type of object that has no geometry of its own, but refers to other geometry.
An image applied to a shader that varies the color information across the surface.
The relative lightness or darkness of a color.
Part of an object. A component is easily identified by examining the SBD (Scene Block Diagram). Any node beneath the top node (object level), and above the bottom node (control vertex level), represents a component of the object.
An image formed by combining two or more images.
The settings in the user interface that determine things such as the coordinate system and what hardware (scanners, plotters, video systems) you can use.
A box that appears when a choice must be made, or an error or other condition must be acknowledged. A confirm box contains an explanatory message and one or more selections.
Being in contact with. For example, a surface is contiguous with another surface when it shares an edge.
Continuity is the existence of a continuous range of values. That is, there are no discontinuities (gaps) in a set of values. When curves or surfaces are being evaluated, finding undesired discontinuities is usually the object of evaluation. Alias provides specific curve continuity and surface continuity functions, as well as tools to create continuity relationships between objects.
A point that controls the shape of a curve or surface (see spline). A CV has a world-space position (its position in terms of the X, Y, Z coordinate system) and a parametric position (its location on its surface, defined in terms of U,V coordinates. As you plot CVs to construct curves, each CV has an initial weight factor of 1. When all CVs have the same weight factor, the curve is said to be non-rational. When CVs on a curve have different weight factors, the curve is said to be rational.
Changing the weight factor of a CV modifies the curve segment that is controlled by that CV. As the weight factor is increased, the affected CV exerts a greater pulling effect on the curve.
A method of describing the placement of a point in some space. In computer graphics, there are several coordinate systems, each one holding the values for the picture at some stage of the graphics process. See also World Space
An arrow or other shape showing the current location of the pointing device.
A connected sequence of straight or curved lines.
A type of curve that exists directly in the parameter space of an existing surface. A curve on surface is typically used in trimming operations, or as a boundary curve for surface construction that will match the curvature of the surface on which the curve was constructed.
DAG stands for "directed acyclic graph." "Acyclic" means that the DAG nodes can not form loops - the hierarchy goes from the top down and never from a lower level to a level higher up. A DAG node is represented in the Scene Block Diagram (SBD) by a rectangle. DAG nodes at different levels of the hierarchy represent groups, sub-groups or components, objects, surfaces, and control vertices. Imagine that a hierarchy is an upside-down tree: leaf nodes are located at the ends of branches. The root node is the node from which all branches originate.
User-generated and user-saved files from painting, modeling, rendering, animation, filming, and printing.
The initial setting of a menu, pop-up, or function. The setting you get when you first start using the system.
A measure of the diffuse component of the light reflected from the surface of an object. The diffuse component carries the color of the surface; the specular component appears as highlights.
A pointer for grouping files. In the SGI Workspace, directories are presented as file folders into which files can be placed and removed. In a UNIX window or shell, directories can be identified by using the ls command with -R, -p or -F options. They are listed with a trailing slash (/).
A texture map that distorts the surface by moving the surface down or up along the surface's vertex normals. Low values move the surface down; high values move it up.
To move the camera forward (dolly in) or backward (dolly out).
To click on an object, and while the mouse button is held down, to move the cursor to another location.
Drawing Exchange File is a file format developed by Autodesk, Inc. for the exchange of geometric and drawing information between microCAD systems.
A way of describing and controlling the size of highlights on an object when using the Blinn shading model.
A point that controls the shape of a curve or surface and is placed directly on the spline.
An end-effector is, typically, the last bone in a skeleton chain; you can use any bone as the end-effector. See Inverse Kinematics.
A texture map that, applied to a surface, provides a reflective appearance without raytracing.
To make a three-dimensional surface or shape by sweeping a curve or face through space. The extrusion will have the curve or face as its cross-section. Extrude is sometimes known as "sweep."
A closed curve that defines a surface. A face may have holes in it. Extruding a face allows you to have faces at either end of the extrusion.
A real-time rendering tool capable of handling Alias models, multiple light sources, texturing, and reflection mapping. As this tool was designed to take advantage of SGI's Reality Engine board set, we suggest that you use this hardware for maximum performance.
Information stored on disk under a name. A file can contain information about a scene, textures, animation, or text.
Type characters (letters, numbers, and symbols) belonging to a specific type face in a given weight, style and size.
A class of shapes that exist in fractal or non-integer dimensions, created by fractal geometry, which applies recursive subdivision to a basic form while introducing a random factor at each subdivision.
Memory used for storing the picture for screen refresh.
A process of adjusting light intensities in a display device (video or film) to achieve correct apparent brightness or colors.
To capture a frame of video or film, and store it in digital form.
A tool that provides a visual reference.
A type of spline curve that passes through the control points. Hermite curves are used in Animation for specifying parameter curve actions.
Surfaces that are obscured from view in the current rendering of the object.
A graphics database that defines the parts of an object in relationship to each other, such that the movement of one part is dependent upon the movement of another part. See also DAG node.
Surfaces which are higher than degree 3 in either parametric direction. Such surfaces may exist as a result of data transfer from other systems. See the introduction to Advanced Modeling.
Hue, Saturation, and Luminance. Three components of the HSL color model. Hue describes the color (red, yellow, etc.), saturation describes the amount of white mixed in (red vs. pink), and luminance describes the overall brightness of the color.
Hue, Saturation, and Value. Three components of the HSV color model. Similar to HSL, but value describes the lightness or darkness of a color.
One component of color. Hue describes the tone of the color (red, yellow, blue, etc.).
A network of lines that join the control vertices of a curve or surface. The hull shows the relationship between two CVs beside one another. When working with B-splines, the hull of a closed curve is larger than, and surrounds, the curve.
Initial Graphics Exchange Specification. A file format for transferring graphics data between computer systems.
The number of pixels in the horizontal and vertical directions.
Computerized interpolation between key frames of an animation sequence.
Gray rectangle beneath the buttons on the menu bar. Information, prompts, and warnings are provided here. Also called the status line.
In inverse kinematics, you describe the target location of an end-effector bone, and the inverse kinematics algorithm determines how each joint must be rotated for the end-effector to reach the target. Inverse kinematics is ideal for working with complex hierarchical objects. Typically, a hierarchy of limbs or parts of a figure is assembled by moving them into relative positions and grouping them in a hierarchy. This is usually known as an "articulated figure."
(Trademark of Silicon Graphics, Inc.) Integrated Raster Imaging System. The name of a workstation family on which the Alias software system runs.
A line of constant U or V value on a surface.
A joint is the rotation pivot point at the top end of a bone node, with three axes of rotation. See Inverse Kinematics.
The state (size, location, etc.) of an item at a point in time is specified by a keyframe in an animation. In-between frames are created by the system.
A layer is an association or a collection of objects completely independent of any group hierarchy in your model. Each stage has a different set of layers.
A source of illumination in the three-dimensional model. A light can be assigned an intensity, color, position, etc.
A lighting model that produces a constant illumination on all surfaces, regardless of their orientations. The Alias system also provides an ambient shade value to give depth to objects.
A lighting model that produces a sheet of illumination with parallel rays traveling along the normal to the surface, like a rectangular light box.
Light from a point light source located at infinity in the user's world coordinates. The rays from the source are parallel and the direction of light is the same for all objects, regardless of their position. A directional light is similar to the sun.
A lighting model that produces lines of illumination, like fluorescent lighting tubes.
A lighting model that produces a small source of illumination that radiates equally in all directions.
Light from a point light source located relatively close to the viewing area. Rays from this type of light source are not parallel, and the position of the object with respect to the light source affects the angle at which light strikes the object.
A lighting model that produces illumination radiating in a cone from the light source.
In Paint, a mask overlay is used to partially or completely prevent painting over an area of the image. The mask can be edited, like the image. A mask can be used to selectively restrict file input operations.
Like mask, but a matte defines the areas of an image to which file input operations are to occur.
A horizontal set of menus located at the top of the workspace window, containing such functions as File, Edit, Display and Render.
A coordinate system used in computer graphics that is used to represent an object in terms you define. For example, a car might be defined in terms of millimeters. Also known as world coordinates.
A data set derived from the digitization of a real-world surface that represents the desired changes to an Alias surface. This data can consist of any combination of curves or surfaces.
An image with a single hue. All variation in the image is based on value or luminosity. Typically, a monochrome image hasgray values only.
A three-dimensional curve that defines the x, y, z position of an item during an animation.
The small rectangular surface upon which a mouse rests.
Hand-held input device used for pointing on screen, which may or may not be used in conjunction with a mouse pad.
Surfaces on which the weight of all control vertices are equal to a weight value of 1.
The orientation of a surface; that is, the direction the surface faces. See also Surface Normal.
National Television System Committee. The body responsible for the NTSC video signal standard in North America.
NURBS (Non-Uniform Rational B-Splines) are a special type of B-spline that can have weighted control points. NURBS create smooth curves that the Alias system can read from many CAD/CAM systems, and vice versa.
Primitives, text, lights, patches, or other items, especially when situated at the top level of the Scene Block Diagram. See also Component.
A window containing choices that may be made for an executable action. For example, the default primitive when selecting MODEL Object Tools primitive is a sphere. By opening the option box, different primitives may be chosen.
An Alias curve that is to be modified or used to construct a surface. Option boxes frequently have a Keep Originals option to retain the original curves once the surface has been built.
An Alias surface that is to be modified.
A parallel projection from one side (top, front or right views, or side or back views), such that a depth cannot be perceived.
One of two full-color bitmap paint packages created by Alias: either DesignPaint or VideoPaint.
A matrix of colors in the DesignPaint and Alias programs.
Phase Alternate Line. The video signal standard used in Western Europe and the United Kingdom.
A plane generated by a point moving so that its distance from a fixed point is equal to its distance from a fixed line: the intersection of a right circular cone with a plane parallel to an element of the cone.
A curve that maps the value of an animation parameter (for example, the scale, rotation, or translation) versus time.
1. (a) An arbitrary constant whose value characterizes a member of a system (as a family of curves); (b) an independent variable used to express the coordinates of a variable point and functions of them. For example, a CV has a parametric surface value. On a curve, this value is expressed in terms of "U"; on a surface, it is expressed in terms of "U" and "V".
2. A physical property whose value determines a characteristic or behavior of something.
A window containing choices that may be made for parameters that affect an executable action. For example, the default shader is a blue Lambert shader. By opening the parameter window, different parameters that affect the shader (such as the shading model, transparency, and color) may be changed interactively.
To express in terms of parameters.
Any of a set of equations that express the coordinates of the points of a curve as functions of one parameter or that express the coordinates of the points of a surface as functions of two parameters. For example, B-splines, NURBS.
Entities used to define a three-dimensional object that are created with a limited number of control points defining the surface's shape and curve, with the remaining points determined computationally. Also known as bicubic patches.
An algorithm for "wrapping" a two-dimensional pattern or texture around the surface of a three-dimensional object so that the pattern curves and distorts realistically.
A linear interpolation between two curves for producing a three-dimensional free-form surface. As a verb, to create the 3D free-form surface.
The trail along which an object is animated.
The name of a file in the UNIX file system (on disk). Pathnames begin with the slash character "/" to signify the top or root of the file system.
A non-orthographic modeling window that provides a three dimensional view of the scene.
A method of shading the surfaces of three-dimensional surfaces developed by Phong Biu-Tuong. The Phong model uses three characteristics, Diffusion, Specularity, and Shinyness, to create a smoothly curving surface with light-reflecting highlights. See also Blinn Shading.
A rectangle drawn from the mouse cursor at the point the mouse button is depressed to its diagonally opposite corner where the mouse button is released after a drag operation. Everything encompassed or partially encompassed by this box has its current active status reversed. The type of entity chosen depends on the selected Pick type.
A picture file used by DesignPaint and produced by Alias RayCasting, RayTracing or QuickRender.
A blending of the words "picture element". A discrete unit of picture information, the smallest unit of raster graphics. The smallest element of a display surface that can be independently assigned a color.
A menu that appears above a button while the button is selected. An item on a pop-up menu can be chosen by dragging the mouse up the menu.
Each point in a cloud of points is the measured position of a sampled point on the surface of the shape represented by the cloud. These clouds are used as a way of scanning three dimensional models.
One of the basic geometric building blocks of object modeling (sphere, cube, cone, etc.) built into the Alias system.
A texture created by a computer procedure with a set of parameters, instead of a 2D pix file. The Alias system provides both 2D and 3D procedural textures.
A limited quality, high speed method of adding surfaces and lights to objects, usually for testing their appearance before rendering.
A high speed hardware rendering of surfaces and lights that permits the user to rotate, scale, and/or translate objects in near real time.
A limited quality, high speed display for wireframe objects. Useful for displaying non-changing objects in a crowded scene while working on other objects.
A range of values that increments from one value to another. Usually used to describe color and monochrome ramps, where the color or gray value linearly or logarithmically changes from one given color or gray value to the other across the extent of the image.
Surfaces on which some control vertices have weight values less than or greater than 1 (but not zero, and generally positive values only).
A technique for rendering scenes in computer graphics. The casting of non-bouncing rays from the eye to the object.
A method for tracing the path of light rays from their source to the viewer's eye as they reflect from and/or pass through the objects (like water or glass) that make up a scene.
An Alias surface that is not be modified but that is to be considered for both position and continuity constraints when modifying the another Alias surface with ClayMate.
In computer graphics, a surface characteristic used to determine color intensity in lighting models, which therefore helps determine how the surface looks.
The bending of light when passing through a transparent or translucent object.
The degree to which light bends when passing through a transparent or translucent object. For reference, the refractive index of a vacuum is 0.0, and of water is 1.0.
The process of creating finished output from a software scene description. The process of producing images or pictures. Rendering techniques such as shading, light sourcing, or depth cueing are sometimes used to make the image look realistic.
To recalculate a surface's U and V parameterization, or to recalculate the placement of edit points on a surface.
Red, green, and blue. Three additive color components used to create any color by mixing.
A transformation turning an object around an axis.
The amount of white mixed in a color (for example, red vs. pink: red is more saturated than pink).
The changing of the size of an object, without changing its location or orientation.
A diagram depicting the hierarchical structure used to represent the objects and sub-objects in modeling. The SBD window displays the structure of a scene. Items can be picked in the SBD window, just as they can in the geometric windows.
A collection of objects, either in wireframe form or rendered Scene Description Language (TM) (SDL(TM)). Used to control all coloring and lighting attributes of all rendered scenes and animations. SDL files are generated by the renderer and can be hand-edited for greater control of the final rendered images.
The maximum number of displayable pixels in the horizontal and vertical directions. Also the number of pixels per inch.
To move through a file vertically or horizontally with the use of either scroll bars or arrows. Scroll bars move through a file quickly; arrows move through the file in small increments.
A set is a selection of objects that are grouped together, but do not have a hierarchy.
An entity containing parameters that affect the appearance of a given surface, including the shading model, transparency, color, refractive index, and any texture maps. Each shader can be assigned to one or more surfaces, and can be stored in a library independent of wire files.
The algorithm used to create the intensity and color of the visible portions of a scene. The shading model usually incorporates the surface normal information, the surface reflectance attributes, and the lighting model.
The difference in color across a surface due to different surface characteristics and lighting.
An area that is totally or partially obscured from light by an object. In computer graphics, RayTracing and RayCasting are two illumination models that can create shadows.
A skeleton is a hierarchical group of bones and joints. See Inverse Kinematics.
An Alias AutoStudio tool to interactively create freeform curves by dragging the mouse.
A surface that fits across a number of cross-sectionals.
An Alias AutoStudio tool to smooth a curve, surface, or section of a curve or surface. The result of the smooth operation is always a curve or surface with a more continuous curvature distribution.
The process of smoothing the polygonal edges of a model to make it appear realistically three-dimensional. See also Blinn, Phong, and Lambert shading.
In the MetaCycle window, snippets represent a single basic movement or cycle that a character may perform, such as a walk cycle. A snippet is specified by acharacter's range of frames in a specified stage.
A procedural texture that, when applied to a three-dimensional surface or group of surfaces, gives the appearance of an object that has been carved from a block of a substance. Unlike parametric textures, solid textures have no edges, but provide a continuous-looking appearance.
The type of reflection that happens when light hits a shiny surface. It causes highlights on the object.
Controls the effect where some surfaces are more reflective at oblique angles. Rolloff values around 0.700 will create a "wet" look on a surface. Specular rolloff is only applicable to Blinn shading. Also affects reflected rays in reflection maps.
A curved line, made up of segments and defined by control vertices (CVs). Includes polylines, cardinal splines, B-splines, and non-uniform rational B-splines (NURBS).
Objects, lights, and environment saved as a wire file for retrieval into a scene.
A 2D parametric shape that defines the boundary or skin of an object in three dimensions. The shape may be flat or warped. Examples of surfaces are patches and faces.
The vector that is perpendicular to the polygon surface. Surface normals are used to calculate surface shading. See also Continuity.
Part of an input device, consisting of a mouse or puck and a digitizing tablet.
A tangent vector is used to determine the slope of a curve or a surface at a given point. See also Continuity.
An object can be made into a template for use as a background drawing or modeling reference (the way a grid is used). The template remains visible, but cannot be picked as an object (it is protected). A template can also be turned back into an object.
The timing curve graphs the percentage of the total length of the motion path traveled versus time. It is used to position the in-between frames along the path. Each object in an animation that has a motion path also has a timing curve.
A mode or a button that turns on or off. Each selection of the mode or button causes the action to be switched.
To rotate, scale, and/or translate a graphical object.
The changing of position of an object without changing its shape, size, or orientation. All points in a translated object undergo a linear displacement.
The amount that light travels through a surface. Complete transparency allows all light through; no transparency makes the surface completely opaque.
Transitions are procedurally defined blends that link snippets together. Transitions can be specified in the MetaCycle window. See Animating in Alias for more information.
A parametric texture map that varies the transparency and transparent color across a surface.
A surface that has been cut by a line, curve on surface, or another surface using Trim.
To revolve the camera by varying the azimuth and elevation angles in the perspective window.
Turntable is an animation-related function that lets you animate an object or group of objects in a circular fashion, as though they were revolving on a turntable. Turntable can be used with QuickShade, FastRender, or any of the other Alias rendering packages.
(Trademark of AT&T/Bell Laboratories.) The operating system under which the Alias program runs.
Lightness or darkness of a color: one component of the HSV (Hue, Saturation, Value) color model.
VDA Surface Interface is a standard file format designed by European auto manufacturers for the exchange of geometric information between CAD systems.
The vector coming from the vertex of a polygon; often an average of the normals from all adjoining surfaces. Vertex normals are used in calculating surface shading. Compare to Surface Normal.
The point or points of a network that terminates or serves as a connection for another line.
An image made up of the edges of objects, and drawn as lines. It resembles a model made of wire. Objects are displayed as wireframes in the modeler. A method of model construction that produces objects defined by a network of straight lines, characteristic of vector-based systems. The drawing of a model by tracing features such as edges or contour lines without attempting to remove invisible or hidden parts, or to fill surfaces.
The entire collection of objects which exist as wireframes in the current working environment.
A coordinate system used in computer graphics that is used to represent an object in terms you define. For example, a car might be defined in terms of millimeters. Also known as "modeling coordinates."
A method of mapping textures onto an object's surface that attempts to ultimately minimize distortion to the texture. Multiple surfaces may be connected to form a continuous surface. World space texture mapping only works on surfaces that will unfold to a flat surface (that is, surfaces that are topologically equivalent to a sheet of paper).
Transform. The transformation of control vertices, curves, or objects by moving, scaling or rotating.
To increase the length of a camera lens, magnifying an aspect of a scene. Note that the results of zoom and dolly are quite different. Dolly physically moves the camera closer to the point of interest without changing the length of the lens; perspective distortions peculiar to the lens length may result at the edges of the scene. Zoom increases the size of the point of interest by increasing the lens length; depth is not as well perceived as with a shorter lens.
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