Glossary of 3D Terms


When a polygon is created, unless otherwise set up, it will have only one side. If you were to look at a playing card, it has a front and a back. A 1-sided polygon only has a front, and therefore only one surface normal.

2D map
Two-dimensional map consisting of either a bitmap or a procedural map. An object using a 2D map needs texture coordinates. See UV for further details.

Like a playing card. A polygon that has a front, and a back, is 2 sided. A 2-sided polygon will have two surface normals, facing opposite directions.

A three-dimensional medium, display, or performance, especially a cinematic or graphic medium in three dimensions.

3D Accelerator Card
A graphics card specifically designed for 3D graphics. LightWave uses a system of 3D graphics called OpenGL and your graphics card must support this.

3D map
Three-dimensional map either built up from multiple layers of bitmaps or, more often, generated in three dimensions with a procedural texture. These are algorithms that can generate 3D maps resembling marble or wood, and when applied to an object, the grains of the marble, and the fibers of the wood, will be correctly mapped to the surface in all three dimensions. If you split a 3D-mapped cube in two halves, the cross section surface will match the neighboring faces. A 3D map does not require texture coordinates.

3D object
Anything with a position and a representation in 3D space. Some objects have a special role, for instance a camera or a light, while others serve as controls for other objects, for instance splines or manipulators. The most common 3D objects are geometric objects, which can be classified according to whether they are polygon meshes, surfaces, curves, implicit objects, or nulls.

3D Shutter Glasses
3D glasses made with electronic liquid crystal shutters. They are powered by the computer they are attached to and use this power to turn on and off the liquid crystal in each of the lenses creating a 3D effect, instead of the usual 2D display a computer monitor can offer.

Aged file format used by Autodesk 3D Studio and discreet 3d Studio max for three-dimensional scenes. It contains geometry, textures, lights and cameras as well as animation data.

Absolute coordinates
The location of a point in terms of distances and/or angles from a fixed origin. See Relative coordinates.

Adaptive supersampling
A way of antialiasing the surface of an object by decreasing the oversampling rate for those pixels that do not require the oversampling. The results of adaptive supersampling are slightly more localized, and the computing time is often shorter than other sampling methods.

Additive mixing of colored light
There are two sorts of mixing of colors. One is called additive, or sometimes transmissive and refers to the fact that the more red, green and blue you add together the nearer to white your final color. This is the normal light scene for LightWave or other graphics packages with output mainly through the medium of a screen. Subtractive mixing indicates that the fewer colors you mix the nearer to white you are and is used for reflective color, such as printed material.

Additive opacity
Type of opacity that adds the background color to the material's color of the transparent object.

Aggregate Object
An object that is made up of a number of other objects. A normal aggregate object will be made up of primitives. A more complex aggregate object may be made up of primitives, other aggregate objects, or both.

A problem-solving method that involves using a multi-step process.

When referring to pictures, aliasing is the effect that occurs when a line looks jagged instead of smooth because of a contrast in colors. Usually, you can tell when this happens because the line between the colors looks very jagged, as if it were a flight of stairs, in fact it is often referred to as a "stairstepping" effect. For contrast, see antialiasing.

Alpha Channel
One of the four channels (or components) of information that make up every pixel in an image. There are three channels for red, green, and blue (RGB) and one alpha channel. The alpha channel is really a mask - it specifies the transparency of each pixel, which allows portions of the foreground image to reveal the background when two images are overlaid.

Alpha matte/image
Alpha matte/image generally refers to an image where the brightness of each pixel is used to cut or partially dissolve out another image. These are generally grayscale or black-and-white images, but the brightness values can also be extracted from a color image.

Ambient component
Part of the reflection-illumination model. A common surface shader parameter that adds consistency to the color of an object's surface to simulate an ambient light that reaches all points in a scene. An ambient value is determined for individual surfaces. Scene ambience is multiplied with an object's ambient color. If the scene ambience is set to black, nothing alters the ambient color of an object except, of course, a light. The careful balance of ambient and direct light sources is the key to convincing lighting. Global illumination is an alternative to ambient light that is more accurate but takes longer to render.

Ambient map
Allows manipulation of the ambient component of an objects reflection-illumination model. Usually the ambient component is given a value near that of the diffuse component.

Ambient Light
All-directional light illuminating every object uniformly from all sides.

Moving or still pictures in contrasting colors that appear three-dimensional when superimposed. Anaglyph works well for printed matter or computer display, but color problems inherent in television displays (both PAL and NTSC) result in poor 3D broadcasts.

Anamorphic Distort
An option referring to the width of a lens flare. When selected, the larger the distort factor, the wider the lens flare will become.

Angle of incidence
The relative angle between a lit surface and the light source. The more the surface is turned away from the light source, the less light it receives and the darker it becomes. When the angle of incidence is 90 degrees, the light shines directly on the surface and it is illuminated with maximum intensity

Animate, Animation
The movement of elements through time and space. Also, the process of creating and recording images that change over time. Everything in a scene is represented by numeric values and, as such, animation is also the process of changing these values - position, color, or any other property - over time. A method of creating the illusion of life or movement in inanimate objects or drawings. Through animation the artist’s drawing comes to life. The most well known works are cartoon comedies, like Ren & Stimpy or The Simpsons, for example.

Preliminary animated versions of a final video or film presentation.

Animation Channel
Animation Channel refers to the different position, rotation, and scaling settings an item can have in Layout. It can also refer to other envelope elements like light intensity. See also motion channel.

The process of inserting text or a special note, explanation or to provide relevant detail to a surface, a rig or a point in your scene in LightWave.

A method for blending harsh contours and preventing staircasing or stairstepping. It is achieved by taking the surrounding areas into account when assigning a color value to pixels lying on an object's contour.

Antisymmetry surface restraint
The restraint of a surface tangent to the surface. This implies that the structure is symmetrical about this plane, and the load on the implied symmetrical part is equal to, but in a direction opposite to, the modeled part.

The opening size of a camera lens. The greater the aperture, the smaller the depth of field and the greater the amount of light entering the lens.

abbreviation for application programming interface.

Regularly curved open element that has a constant radius around a single center point. A section of a circle.

Area light
A special kind of point or spotlight. The rays emanate from a geometric area instead of a single point (entire surface uniformly emits light). This is useful for creating soft shadows with both an umbra (the full shadow) and a penumbra (the partial shadow).

A set of elements put together into a single entity. A pixel array is an ordered set of colored elements used for display purposes. In a 3D program, the array tool is usually used to create ordered copies of an object within 3D space. This tool is so named because it creates arrays of objects (creates an ordered set consisting of multiple copies of the same object).

Aspect ratio
A description of the proportion of an image by comparing its width to its height. 35 mm slides have the aspect ratio of 4:3 (1.33:1). Images become distorted if forced into a different aspect ratio during enlargement, reduction, or transfers. It should not be confused with the pixel aspect ratio, explained further on.

In LightWave, a volumetric effect that simulates reduced visibility in air over distances.

When light travels through air its strength diminishes with the distance. The further the light travels, the dimmer the light. In real life, the light attenuates by the inverse square of the distance. This means that if attenuation is turned on for a light only the geometry in its proximity will be lit. Not only is this more realistic for your renderings, it also helps speed up rendering time since only the geometry close enough to be affected by the light needs calculation time. See also Decay.

A popular file format that combines video and audio. It stands for Audio Video Interleave.

Axis of Motion
In 3D space, the line that an object follows during movement.

Axis of Rotation
In 3D space, the line that an object rotates around.

Axis, Axes
The reference for describing the origin and position of an object in space, displayed by intersecting straight lines. By using two axes, a plane is determined; for example, the XY plane is defined by placing the X and Y axes so that they intersect at the global center (point of origin). Three dimensions are determined by using three axes: X, Y, and Z.

B rep
Slang for boundary representation

Backface culling
A process included in most 3D graphics pipelines, backface culling eliminates triangles facing away from the camera. This is most efficiently performed by checking the orientation of the triangle normal in relation to the camera. The technique ignores geometry seen from behind so that only the fronts of objects that are facing the camera are rendered. Both faces of an object are rendered by default; that is, the ones whose normals are facing the camera as well as those that are not. You can choose which faces of the object you want to render as part of the rendering options: front, back, or both faces. Back culling (rendering only the front) can improve performance because less geometry needs to be rendered.

Backface elimination
See backface culling.

Background Color
The color that occupies all space not occupied by text, images, or any other objects. By default LightWave's background color is black.

Another name for a sphere. Basically, a ball is a 3D circle or oval created by user-defined dimensions and settings.

How much information a network can carry. Think of the network as a highway, and each message as a car. The more lanes in the highway, and the higher the speed limit, the more traffic it can carry. So the wider the bandwidth of a network, and the faster its speed, the more information it can carry.

This is when an object following a path rotates about the path when it changes direction.

Bank Shot
A shot in billiards in which the player causes the cue ball or an object ball to rebound off a cushion. A shot in basketball in which the ball glances off the backboard before reaching the basket. Also a shot fired during a heist.

Barn Doors
The flaps on the front of a movie light to assist in limiting the beam of light.

Bits per second. Hence kilobaud or Kbaud, thousands of bits per second. The technical meaning is `level transitions per second'; this coincides with bps only for two-level modulation with no framing or stop bits. Most hackers are aware of these nuances but blithely ignore them.

To deviate from a straight line or position: The lane bends to the right at the bridge. To assume a curved, crooked, or angular form or direction: The saplings bent in the wind.

A method of eliminating sharp edges from objects by extending an object’s faces.

Bezier Curve
A technique for creating curves that was attributed to and named after a French engineer, Pierre Bézier, who used them for the body design of Renault's cars in the 1970s.

Bilinear Filtering
Blurring the pixels in a bitmap when it is zoomed in so that it seems smoother than it really is

Bilinear intensity Calculation
A high-speed algorithm for generating shaded faces. Used in Gouraud shading and Phong shading

Binary Space Partition
Also known as BSP, this is a technique used in real-time rendering for resolving in which order polygons should be drawn. The technique requires that a so-called BSP tree is built before the scene may be rendered. As this build process is very costly in terms of execution speed, BSP trees cannot usually be calculated in real-time and thus essentially only support highly complex yet static 3D worlds

The building blocks of computer data. Has either the value of 1 or 0 (current or no current). Bits can be grouped together to carry larger values.

Two-dimensional monochrome raster image. A bitmap is a black and white image marking boundaries. It is often used for clip maps in LightWave.

A thin plane placed in front of a light to cast a shadow, taking light off of an object. A device to create a shadow.

The mixing of two (or more) textures into one final texture that is displayed in rendering, or the final step in making a margarita.

The copying of a virtual frame buffer to the displaying screen.

Bone Hierarchy
Bones can be arranged to build a Bone Hierarchy, also called a Skeleton. The hierarchy defines how the movement of one bone affects other bones (up and down the hierarchy). If you then also add Constraints to the bone hierarchy, you have a Rig.

The basis of movement for a model. Bones define parts of a model and how they move in relation to each other. Bones can be created in any object, even those which would normally be considered to be inanimate, to give life to that object and make it move smoothly.

A mathematical system developed by George Boole that expresses logical relationships between things. The results in a Boolean operation can be either true or false. Boolean is used in 3D to add, subtract, and other operations that involve Boolean calculations.

Boolean operations
A modeling technique that uses two objects that are overlapping to create a new object. There are three kinds of boolean operations: subtraction, union and intersection. By taking the first shape and subtracting/unifying/intersecting it to the second - a new shape is created.

Boom shot
A camera move. Usually describes a shot in which the camera is mounted on a crane. The camera can move in all axes of movement.

Boundary Representation
A polygonal mesh representation. A polygonal mesh is, most commonly, a simplification of a shape using facets to describe curvatures. Its surface, or boundary, is built up from several faces that describe the shape. If it is a polyhedron the polygon model can be identical to the shape, whereas an organic shape is represented by a more or less simplified version that mimic the curvature using facets with variable density.

Bounding Box
A cubic shape that exactly circumscribes a (more complex) 3D model and is used to optimize three-space calculations like ray tracing. By representing a more complex shape with a box, possible ray intersections can be investigated much more swiftly. Also used to represent complex objects for proxy animation and setup to speed up operations.

Bounding Volume
A way of speeding up ray tracing operations involving intersection calculations, by inscribing a complex mesh in a considerably less complex shape like a box or sphere. Often used when rendering must be done in a short amount of time. Instead of having to check the intersection of a more complex mesh, like a space ship or a teapot, the bounding box works as a stand-in, with the same maximum height, width and length as the mesh it substitutes for. Therefore a possible ray intersection can be either ruled out (if the ray doesn't pass through the bounding box, it doesn't pass through the mesh either), or let a more time-consuming algorithm take over working with the complex mesh instead.

Another term for a cube. This is a six-sided 3D object that can be thought of as a 3D square or rectangle. Boxes are created based on user-defined input as to the dimensions and locations desired.

abbreviation for Binary Space Partition.

A free-form curve that is defined with parameters in which each separate vertex on the curve has an influence over a portion of the curve. In 3D, B-splines allow a user to control a curved line on two axes at once.

Bump Array
See also: array. The purpose of a bump array is to create an ordered series of bumps in a surface. This tool means exactly what its name implies - an array of bumps.

Bump Map
Creates the illusion of three-dimensionality of a surface (protrusions and cavities) by recalculating the normals of the object, without changing the mesh itself. It is very common in 3D renderings and suitable for creating effects like wrinkles, creases, crumples, cracks, seams etc. The silhouette of a bump mapped object is a give-away since, in these areas, it is obvious that the mesh is left unaffected (if trying to create an orange by using a perfect sphere with an orange peel texture applied to it for bumpmapping will still have a impeccably round silhouette). In LightWave areas in a bump map that are black are unaffected and areas that are white are raised.

8 bits. Multiples of bytes make up the terms kilobyte (1024 bytes), megabytes (1024 kilobytes) and gigabyte (1024 megabytes).

Computer Aided Drafting (or Design); A system that lets a designer use a computer screen instead of a drafting table to make plans and blueprints. Designers can use CAD for anything from the largest building to the tiniest screw.

Computer Aided Manufacturing; the process of using a computer to create a physical product from a computer-created design. CAM is usually used to control robots that perform tasks that would be tedious or dangerous to human workers. See also Rapid Prototyping.

An apparatus for taking photographs, generally consisting of a lightproof enclosure having an aperture with a shuttered lens through which the image of an object is focused and recorded on a photosensitive film or plate. Nowadays, young technobods also use digital cameras, which use CCDs to focus light and create a digital picture that can be seen and transferred to a computer immediately. In LightWave terms, the camera is the conduit through which your objects and scenes are turned into still images or animations.

Surface closing the upper and/or bottom side of an object such as a cylinder.

Cartesian Coordinate
A mathematical representation of Euclidean space. Every point can be described by three coordinates (X, Y, Z) representing the position along the orthogonal X, Y, and Z axes. The point (0, 0, 0) is called the origin, which is the global center of the 3D world.

Cartesian Space
A space in which positions are denoted by a three-coordinate system (x, y, and z coordinates) relating to a central origin (0,0,0).

slanted across a polygon on a diagonal line; "set off in a catty-corner direction across the vacant lot". syn: cata-cornered, catercorner, cater-cornered, catty-corner, catty-cornered, kitty-corner, kitty-cornered

All outtawhack.

Light pattern created by specular reflection or refraction of light, such as the patterns of light on the bottom of a swimming pool, or light through a glass of wine.

Abbreviation for Cadmium. A soft, bluish-white metallic element occurring primarily in zinc, copper, and lead ores, that is easily cut with a knife and is used in low-friction, fatigue-resistant alloys, solders, dental amalgams, nickel-cadmium storage batteries, nuclear reactor shields, and in rustproof electroplating. Atomic number 48; atomic weight 112.41; melting point 320.9°C; boiling point 765°C; specific gravity 8.65; valence 2. Also used to designate compact disc storage media.

Center of Projection
The point in perspective projection where all projectors intersect.

Center of the World
Is the absolute center of a 3D space, represented by X, Y, and Z points (0, 0, 0). Also referred to as the Origin.

Center Point
A point that represents the center of an object. This point is used in some programs for a point of reference for rotation and position. The center point of a polygon is where the line representing the normal comes out from.

To cut off the edges of the geometry with a planar cut, creating a more blunt shape, typically at a 45 degree angle; A beveled edge or corner between two intersecting lines or surfaces.

An object whose movements are influenced by another object, called the “parent”.

Chord Length Parameterization
See non-uniform parameterization

Clean Modeling
Refers to the practice of removing geometry from a model that is not wanted or needed. Also refers to the use of proper geometry construction techniques, such as creating continuous surfaces, minimizing narrow faces, and avoiding small corner angles, that facilitates downstream processes.

More often than not, much of the graphics drawn for a specific scene does not fit into the viewport of the camera. Accordingly, those which fall outside of the viewport must be clipped so as they are not drawn. Depending on the nature of the application, there are two kinds of clipping: 2D and 3D. The earlier simply compares each pixel against the extents of the rendering viewport, while the latter technique uses the six sides of the view frustum to determine whether a 3D vertex is inside the viewport or not.

This tool creates copies of an object based on user-defined parameters for offset, motions, morphing, shadows, etc. This tool can be used to make ordered sets of objects, but is different from the array command because not all of the new objects will be exactly the same as the original.

Cloud of Points, or Point Cloud
A set of x-y-z coordinates obtained from a 3D scanner or digitizer. The data can then be turned into a continuous surface and used as a 3D model.

Short for “compressor/decompressor”. This is the term used to reference the way that software programs handle different movie files, such as Quick Time, AVI, etc. The CODEC can control image quality, and can assign the amount of space given to the movie file. First, a multimedia publisher uses a codec to squeeze more sound and video into less file space. These compressed files are easier to fit on a CD-ROM and transfer to your computer. Then, your computer uses a codec to expand these files back to their original size and replay them on your screen.

Refers to geometry that occupies the same spatial location. For example, coincident vertices are points that occupy the same x, y, and z coordinates. Coincident lines can have differing lengths while one occupies the same location as the other.

Color Bleeding
When the color from one surface reflects onto another surface.

Color Depth
The number of bits used to represent a color. For example an 8-bit image uses 2^8=256 colors. The bits build up the three primary colors red, green and blue.

The bits are divided into red, green and blue (optionally an alpha channel as well). For example a 16-bit color could look like this R: 4-bit (16), G: 4-bit (16), B: 4-bit (16), Alpha: 4-bit (16) - together they add up to 16-bits. The number of bits can also be unevenly divided (R:5, G:5, B:5 Alpha:1).

This is why a GIF (max 8-bit=256 colors) only sports 128 colors if it is transparent (1 bit is used to represent transparency in the alpha channel, 7-bits = 7^2=128).

The following table indicates the number of colors an image can have.
8-bit = 2^8 = 256
16-bit = 2^16 = 65536
24-bit = 2^24 = 16 million
32-bit = 2^32 = 4.3 billion

You should also be aware of FP, or HDR images.

Color Model
A system used to specify colors. In LightWave, you can set color according to the following color models: RGB (red, green, blue), HLS (hue, lightness, saturation),  HSV (hue, saturation, value) or integer values.

Color Keying
An old technique of combining two images by replacing one color of the destination image by the corresponding pixels of the source image.

Column Interleaved Format
The 3D image format used by the VR-4200 projector. Left and right view image data are encoded on alternate columns of the display.

Compiled Vertex Array
Array of geometry data on a vertex level that is optimized (compiled) for faster access by the graphics card. (Note that this is an OpenGL term, and is known by other names in other APIs.

A layering technique that places one image on top of another, properly taking transparent pixels, apparent depth, shadowing and other elements that make up an image into account.

Having a common center or origin point with varying radii.

Cone angle
The angle at the peak of a cone.

Element having the form of a cone.

Conic section
Curve formed by the intersection of a plane with a cone.

Values in a geometric model that define relationships, i.e. a line is tangent to a circle. Constraints are often used to drive parametric or variational geometry-based systems; the algorithms used to work with constraints are known as constraint management.

Continuous LOD
Short for continuous Level-Of-Detail, this method is based on the observation that 3D objects located far off in the distance may be approximated by simpler versions without loss of visual quality, thus increasing the rendering performance. The "continuous" refers to having the algorithm constantly recompute the detail level of the 3D object depending on the distance to the camera instead of having a pre-computed set of objects to choose from. Computationally expensive, this method is most often used in height field rendering applications. LightWave can approximate continuous LOD by using an Object list.

Convex Volume
A convex volume can be defined as a volume whose every corner can be visible from all other corners in the same volume. Another way of defining the convexity is that all faces in the volume will be lit by a point light located anywhere within the volume.

A device put in front of a light, to break the light up. Common cookalorises look like leaves on trees, or blinds on windows.

A small, usually flat and crisp cake made from sweetened dough. Also, slang for a cookaloris.

Coons Patch
A free-form surface that is determined by the four curves that define its edges.

Refers to two or more entities that lie on the same plane. Two planar surfaces, for example, that lie on the same 3-dimensional plane are considered coplanar. If these coplanar surfaces share a common edge, it is recommended that they be joined into a single surface.

Cross Product
Using two vectors to calculate a normal of those two.

A view of the interior of an object as it is sliced along a plane.

Cubic Image Map
One of the many methods of applying a texture to a surface. This method applies the texture to an object as it would apply the texture to a cube. There are many other methods of texturing objects, such as Planar and Cylindrical image mapping.

Curvature Continuity
A curvature continuity with smooth transition of the edges of two meeting surfaces (the highlights of the two surfaces blend together seamlessly, forming the illusion of a single shape). If a curve (or surface) has tangent continuity and both the 2D curves (or 3D surfaces) have the same radius a very smooth transition is created with curvature continuity. Curvature is defined as 1/radius. Hence, small radius equals high curvature

In computer graphics, there are different ways of representing a curve, for example using NURBS and Bezier curve, so see those terms, okay?

Curve Parameterization
See parameterization

Abbreviation for compiled vertex array.

Cylindrical Image Map
One of the many methods of applying a texture to a surface. This method applies the texture to an object as it would apply the texture to a cylinder. There are many other methods of texturing objects, such as Cubic and Planar image mapping.

Phenomenon where the light intensity decreases with the distance. The further away from the light source, the less intense are its rays. In the real world the decay is proportional to the inversed square of the distance (quadric decay), but there is also directional (one-dimensional) decay (slower than in real life) as well as cubic decay (faster than in real life). See also attenuation.

Process of returning a compressed file to its full size (or a diver to the surface if he has been on a particularly deep dive).

Default unit
The Default unit is the unit of measure (ex. meter, feet, etc.) that is assumed, usually when no unit of measure is entered with the numeric data. In Layout, it is determined by the setting on the General Options tab of the Preferences panel. In Modeler, the setting is on the Display Options panel.

Depth buffer
Same as a Z-Buffer.

Depth Cueing
The process of reducing the apparent sharpness of an object the farther away it is from the viewer or camera. This often enhances the perception of depth.

Depth of Field
The total distance, on either side of the point of focus, which, when viewed from an appropriate distance, APPEARS sharp in the final print.

Depth Sorting
Sorting all triangles in the world depending on diminishing depth (lower and lower z-value) so that when they are rendered, the triangle closest to the viewer is obscures those behind it.

Process used to remove skew or distortion through a small angle rotation.

Diffuse Component
Part of the reflection-illumination model. The diffuse is concerned with the amount of light that is reflected back.

Diffuse Light
A component of the reflective model that is the result of direct illumination.

Diffuse Map
Replaces the diffuse component of the reflection-illumination model, basically giving the illusion of being painted onto the surface. To create a material resembling wood or marble, this map is used. Generally, when you talk about the "texture map" in an application, this is the map actually referred to.

A measure of spatial extent, especially width, height, or length.

Directional Light
Another name for a distant light.

Director of Photography
The person on a movie set that determines how to photograph the movie.

A shape that is referred to in mathematics as a cylinder. This shape is composed of two circular or oval-shaped bases and the space contained between those bases. In other words, a disc is like a stack of circles with set parameters defined by the user.

Displacement Map
Can be used to modify the actual mesh (as opposed to the bump map) to create wrinkles, creases, crumples etc. The displacement map will need a more complex mesh to create the same effect as bump mapping, but has the advantage of allowing more thorough close-ups, since the surface is actually deformed and not just simulated as being so.

Display Types
Ways of displaying objects in a viewport. Display types are available only for geometry views. The available display types are Bounding Box, Vertices, Wireframe, Front Face Wireframe, Shaded Solid, Textured Shaded Solid and Textured Shaded Solid Wireframe. Display types do not determine the quality of the final render.

Distant Light
A light with color, intensity and direction. All rays emitted from a distant light are parallel, and therefore it has no obvious source.

Distant lights can be used to simulate point lights from a great distance (whose rays can be approximated to be parallel) like for example the sun. The intensity from a distant light does not decay.

Creating the impression of having more color on the screen than there actually are by plotting pixels (with a limited amount) of different colors next to each other.

Abbreviation for depth of field.

To move the camera along its line of sight (in a straight line following the imaginary path between the actual camera and its target point).

A hardware lock used to prevent the piracy of LightWave. A common question from people who have pirated LightWave is "what's a dongle?"

Dopesheet, Dopetrack
Two animation tools in LightWave that allow the user to better organize his keyframes.

Dots per Inch, dpi
In a bitmapped image, the number of dots that exist within each inch of the image. This number remains constant, so when you make an image larger, the quality decreases, but when you make the image smaller, it appears to increase.

Double Buffering
This is the process of using two frame buffers for smooth animation. While the image of the first buffer is being displayed, the graphics controller can use the second buffer to build or render the next image. Once the second image is completed, the buffers are switched. Thus, the result is the appearance of smooth animation because only complete images are displayed, and the process of drawing is not shown. You can often now see Triple buffering in graphics cards to allow an extra buffer for the next image in case there is a problem.

Abbreviation for Director of Photography.

A high-density compact disc for storing large amounts of data, especially high-resolution audio-visual material. Abbreviation for digital video disc or digital versatile disc. A DVD used solely for a computer is commonly referred to as a DVD-ROM.

AutoCAD native file format. It can contain 3D data, but is hard to convert to a LightWave-native format because of its construction. A DWG file is parametric, that is to say it does not contain the objects themselves, but rather instructions on how to build the objects. This makes it hard to translate if you do not possess a license of AutoCAD. The solution is to either get one or get your client to supply you the object in a different format, preferably OBJ.

The reduction in the acceleration or deceleration of motion to present a smoother, more continuous movement. The shape of a function curve can reflect this when using a spline interpolation.

A straight line connecting two points on a polygon. LightWave does not allow you to select edges as discrete elements of a 3D object, but selecting the aforementioned two points does the job.

Edge Loop
A particular method of modeling organic shapes with the edges of polygons creating a loop or a flow around circular features around the eyes and the mouth for example.

Environment Map
Map often used to simulate (faking) reflection of the surrounding world without using ray tracing.

Euler Angles
Euler angles are one of the simplest methods of representing 3D rotations, and generally also the easiest to visualize. An object's rotation can be specified in terms of its yaw, pitch and roll, or rotation around the Y, X and Z axis, respectively. Euler angles suffer from singularities in the form of so-called Gimbal lock, however, and are also difficult to smoothly interpolate for keyframe animation

Mathematical expressions that allow you to change the animation of an object. You can also create constraints between objects using expressions or create conditional animation. Expressions are very powerful for creating precise animation and to create automated animation of things such as wheels.

External Attributes
The position of the camera and the direction it's pointing.

Creating a three-dimensional object from a two-dimensional shape by adding a third dimension to it. You can also do this along a motion path or spline.

The shape made up by the bounding point making a polygon. Faces can have as many vertices as wanted, but only polygons having a shape of three or four vertices can be made into sub division surfaces.

Face Normal
Also just known as the normal, this is a line perpendicular to the face that also describes which way the face is pointing in a one-sided polygon.

The volume starting at the outer rim of a spotlight's hotspot, decaying from full intensity at the start to zero intensity at the outermost rim of the spotlight. The less the difference (in angles) between the hotspot/falloff, the crisper the shadows. If the falloff angle is much larger than the hotspot angle, the boundaries of the area lit up by the spotlight will be fuzzy. NOTE: in real-life, you are unlikely to find lightsources with a hotspot angle close to the falloff angle. Normally, the edges of shadows are not too crisp, but smooth, so a word of caution might be in place to prevent overusage of sharp edged shadows.

Field of View
(FOV) The angle of the view frustum. The wider the FOV, the more you see of the scene. Human eyes have a FOV of about 50 degrees, and normally virtual reality application use similar values to resemble real life.

Field Rendering
An option that causes the program to render two interlaced fields of information. This is in contrast to rendering only one (full frame) and makes moving objects appear to move more smoothly. Used for projects that will play back on television monitors that display 50 or 60 interlaced frames per second. Fielded animation is not useful for animations designed to be display on computer monitors. See Fields.

Field Sequential 3D Video
The most common format for 3D video. Left and right image data are encoded on alternate field of the standard video signal.

Interlaced images (video) consist of two fields that are combined into one frame. Each field contains half the scan lines (either even or odd) and is a separate pass. This is more common to render to for TV broadcast. Horizontal movement of items will strobe without rendering to fields.

Fill Light
Additional light sources assisting the key light in a scene. Usually they are less intense than the key light and created using point light or spotlight.

To round off the edges of an object with a round shape. Think "router", use "Rounder" in Modeler to achieve it.

The amount of pixels from a texturemap (texels) that is rendered per time unit. Measured in texels/second.

Filter Opacity
Type of opacity that uses a color to simulate object opacity.

A small strip placed in front of a light to cast a discrete shadow.

Abbreviation for forward kinematics.

A device placed in front of a light to create a shadow. A flag is large, to remove light from a large area.

Flat Shading
Shading technique where all individual faces in a mesh are assigned a single color value based on the orientation of their face normals.

Flatness is used as a threshold in determining if a polygon is non-planar. A flatness of 0 percent means the polygon is absolutely flat. Flatness is computed as percentage deviation from a triangle (the “ideal plane”) formed from the first two and last vertices of a polygon. All of the other points are measured relative to this plane. The largest deviation is divided by the total size of the polygon to get a percentage that is the flatness value. For example, if a polygon is 1 meter wide, 5% flatness means that no point will be outside the ideal plane of the polygon by more than 5 millimeters. (1 x .005)

Floating Point (FP) images
Refers to images that do not use standard color depth models to represent the colors contained in them, but rather an expression of the floating point value of a color changing from 0 for black up to 1 for the brightest point in the image. A mid-gray in such an image would be represented by R: 0.5, G: 0.5, B: 0.5.

Focal Length
The distance between the lens and the light-sensitive surface on the backplane (the film in real-world cameras). The lower the focal length, the more of the scene is visible. Focal lengths less than 50 mm is called wide angle, while lengths greater than 50 mm is referred to as telephoto lenses. The longer the lens, the narrower the field of view. Distant details becomes more visible. The shorter the lens, the wider the FOV. More of the environment is visible in the rendered image. To simulate the human eye, you can use values of about 50 mm.

Simple yet effective graphical effect most often used in real-time graphics to obscure the far plane, thus bounding the viewing distance of the application. There are essentially three types of fog: table-based, vertex-based, and volumetric. Fog values may also follow linear or exponential curves. It can also be found in graveyards during a full moon on Halloween.

Foreground Image
The image closest to the camera.

The apparent effect of viewing an object on its long axis that makes it seem shorter. For instance, an arm pointing directly at the camera seems to lose its length as does a road going directly away toward the horizon.

Formula-defined Shapes
Refers to shapes that are defined by using one or more equations. This includes complex shapes such as aesthetic bottles or simple shapes such hyperbolic paraboloids, oblate spheroids, prolate spheroids, or ellipsoids.

Forward Kinematics
Figure positioning by joint angle specification. Like posing a toy action figure.

Abbreviation for Field of View.

FPS stands for Frames per Second. This is the main a unit of measure that is used to describe graphics and video performance.

A single complete picture of an animation. A frame is a static image which, when followed by other static images sequentially, gives the illusion of motion. You can render to frames or to fields. One film frame is 1/24th of a film second. One video frame is either 1/30th for NTSC or 1/25th for PAL.

The memory a computer uses to hold one or more frames for later use.

The speed at which a frame of animation is shown, usually expressed in frames per second. US TV is typically 29.97 frames, European is at 25 frames per second and movies are projected at 24 frames.

To convert from vector or interpolated geometry (splines, NURBS, subdivision surfaces) to pure polygons. Even if the renderer supports NURBS or subdivision surfaces, this freezing happens at render time, and is usually definable to the level of polygon creation by the user.

The part of a solid, such as a cone or pyramid, between two parallel planes cutting the solid, especially the section between the base and a plane parallel to the base. See view frustum.

Slang, to fake it, or to stretch the normal rules.

Shorthand term for effects.

GCore (Geometry Core)
The engine in LightWave that handles all animation and modeling tools.

Generic Primitive
Simple 3D objects that most 3D programs can create easily. These objects typically consist of spheres, cylinders, cubes and cones.

The points of an object. These points are usually seen with objects that can be rendered. For example, a cube's geometry is composed of eight points. By this definition, a curve has geometry since it is also composed of one or more points, whereas nulls have no geometry. Geometry refers to the positional layout of points and polygons for an object. The mathematics of the properties, measurement, and relationships of points, lines, angles, surfaces, and solids.

What happens when two axes of rotation line up, thereby making 3-dimensional rotation impossible. Here's an easy illustration, take any object with neutral rotation (0 degrees on heading, pitch and bank) and rotate in the pitch 90 degrees. Now, try to rotate in the bank. This is gimbal-lock.

See null object.

Global Illumination
Unlike the local illumination, this method of generating images supports effects not only linked directly to the light sources themselves. In real life, the intensity of a surface not only depends on direct illumination from the light source itself, but also from indirect illumination from surfaces being lit. First there is ray tracing that can cast shadows from one object onto a surface, allow objects to be reflected in shiny surfaces or refracted in transparent materials.

Then there is radiosity, the effect of reflected light. If you have spotlights projected at the ceiling in a white room, the light would bounce back and light up the entire room. However, this can only happen if the renderer supports radiosity or other similar techniques, which ours does. Hurrah!

This option affects how spread out across a surface a highlight caused from a light is. Low glossiness makes a spread out highlight while high glossiness creates a more central, pinpointed highlight.

Glossiness Map
An image to control the glossiness of a surface. Bright values in the image indicate more glossiness, dark values less.

Optical light effect that looks like a fuzzy disc around the center of a light source.

An object used in IK to create a point where an object will always reach for. This is used to make objects appear to have realistic motion. Also to score a point in most sporting events.

Gouraud Shading
Developed by Henri Gouraud in 1971, this is a fast incremental shading technique using bilinear intensity calculation to create smooth transitions between the vertices in a triangle. It is most often used for lighting purposes by computing the vertex normals in the polygon, calculating the light values for each vertex, and then Gouraud shading the polygon. Even though it has obvious advantages over flat shading, the facets in the mesh can still be discerned. The placement of the highlight depends on the underlying polygons.

Graphical User Interface
The graphical interpreter between man and computer allows a more intuitive interaction with the computer. The window maker in UNIX, and Windows for the PC are both GUIs. This way you don't have to be computer literate to the same extent as if you should have to type all commands you wanted the computer to perform.

English slang. This describes the non-such little details on objects, usually mechanical objects. Those details such can be found on spaceships, in engine rooms, etc. You can also use the words "didges", "nurnies" and "doohickies".

Abbreviation for Graphical User Interface.

Optical light effect that forms concentric circles around the center of a lightsource. Often clearly visible around street lights after a rainy day.

Any element that is not shown in the current rendering of the scene but still exists.

Hidden surface removal
Algorithm for removing obscured polygons in a three-dimensional view space. As opposed to the faster algorithm backface culling, the hidden surface removal algorithm is able to sort out those polygons that are obscured by another object. Another way of finding an obscured polygon is the z-buffer.

A way of defining objects in relationship to each other (using a parent-child or tree analogy). This relationship means that transformations, deformations, and any other property of the parent object affect all child objects. This allows separately modeled objects to be used in a scene as a single functional unit. The movement of a parent affects the movement of the child, but you can move the child without affecting the parent.

High Dynamic Range Image
HDRI is an image with a wide intensity range between the brightest and darkest pixels. In typical 8/24-bit images, the maximum possible intensity range is 255 times brighter than the darkest gray pixel (with a value of 1). Natural scenes and images rendered with radiosity can have dynamic ranges from 10 to 10,000 times greater than this. Recording this information requires use of an image format with higher precision.

Reflection of a light source on an object's surface. The size of the highlight (the area that shows the light source reflection) depends on the angle. Consequently, multiple light sources results in multiple highlights. This is also the specularity.

HLS color model
Hue, Lightness and Saturation: the three components of the HLS color model. Hue refers to the position of the color in the spectrum, such as red, yellow, or green. Lightness is the amount of white mixed in a color, such as the difference between a pure red and pink. Saturation is the purity of the color, such as the difference between a pure red and a dusty rose - low saturation means that there is grayer in the color.

The inner intense cone of light emanating from a spotlight.

HSV color model
Hue, Saturation, Value: the three components of the HSV color model. This color model defines the hue and saturation similar to the HLS model. Value is similar to lightness, as in HLS; however, a value of 1 represents a pure color when saturation is 1, while a lightness of 1 yields white no matter what the saturation. In both systems, 0 is black.

Hub, The
The Hub is a module in LightWave that allows the Layout and Modeler modules use to synchronize information. It uses the TCP/IP protocol to transfer information between modules.

The position of the color in the spectrum that describes the tone or tint of a color, such as red, yellow, or blue.

Voxels are volumetric rendering effects. HyperVoxels are voxels that are applied to nulls, points, or objects.

Abbreviation for Inverse Kinematics.

Image instance
A copy or instance of a source image. Each time you use a source image, an instance of it is created. You can have as many instances of the same source as you need. You can then edit, crop, or even blur the instance without affecting the original source image.

Image Map
An image that is applied to an object's surface.

In My Opinion.

The emission of visible light by a hot object. In LightWave, this is the luminosity channel.

Incremental shading
See interpolative shading.

Indirect illumination
Light that bounces of one surface and illuminates another surface. This can only happen if the renderer supports radiosity. Does the LightWave renderer support radiosity? Yes, of course!

Intelligentities refer to LightWave's object format. The object format can contain morphs, multiple layers, and independent pivot points on a per layer basis.

The strength at which the light source illuminate objects in the scene.

Interference Checking
The process of identifying if and where two or more pieces of geometry (usually solids) intersect. When moving parts are involved, a kinematics analysis is used to detect interferences.

Internal attributes
The properties of the camera such as depth of field and line-of-sight.

The process used to estimate an unknown value between two or more known values. In animation, interpolation is the process used to calculate values at frames between two keyframes in a sequence.

When a reflective object reflects another reflective object. For example, if you place two mirrors in front of each other, the first one will display the second one, who, in turn, shows the first one. In real-life, there is virtually no upper limit of how many interreflections that may occur, whereas in 3D rendering, one must set an upper limit to be able to render the scene. The default value for LightWave is 16, but it can be lowered to 0, if desired, or up to 24 at a cost in increased rendering time.

Inverse Kinematics
The process of determining the motion of joints in a hierarchical 3D object given the desired start and end points, all the while obeying the laws of kinematics. Think of it like the strings on a marionette puppet.

IR Transmitter
A device that sends synchronization signals to wireless shutter glasses.

Isometric view
Standard view in a 3D design where the top, front, and right side faces of a cube are equally inclined to the screen surface.

An item in Layout refers to an object, bone, light, or camera.

JPEG (Joint Photographic Experts Group)
A widely accepted, international standard for compression of color images.

Stereoscopic JPEG file. JPS refers to a stereoscopic image file format that is based on JPEG compression. Used by DepthCharge & other stereoscopic imaging applications.

A special directory used by some studios to hold mechanical and non-organic pre-modeled parts.

Key, Keyframe
A marker on the animation timeline that shows that a node's (e.g. an object, a material or a light) attribute (e.g. position, color or intensity) in the scene graph has been assigned a new value. Most animation programs interpolate the node attribute values from one key to the next, creating smooth transitions - so the user does not have to key every single frame. See also tween.

Dominate light source in a scene, normally created with a spotlight.

The properties of each 3D object that control its transformations. These transformation properties are used to modify the selected object's scaling (size), rotation (orientation), and translation (position) in X, Y, and Z in either local and global space. Although related, kinematics are not to be confused with inverse and forward kinematics for animation.

An expression taken from model making. The practice of using model kits to give detailing to a larger project. This is still in use. It refers to the taking of models that you have already made, to use in the creation of another, perhaps even basically unrelated.

One way to perform a selection of point(s), face(s), or polygon(s). This method involves drawing a loop that encircles all of the objects that need to be selected.

Latent surfaces
Surfaces that are no longer visible after a Boolean or intersection operation because they lie inside or outside the solid.

Creating a three-dimensional object from a two-dimensional shape by rotating it around an axis.

Either a way of deforming object using a lattice or a way of creating outlined geometry.

A portion of a scene. Each layer consists of an object or multiple objects that can be edited separately from the rest of the objects in a scene. A layer is basically a building block for a scene and each layer contains separate blocks for a final model.

Left-handed coordinate system
Coordinate system where the positive part of the Z-axis goes away from the observer (from the screen).

Part of the camera determining the optical characteristics of the image, such as wide angle, fish eye and depth of field.

Lens flare
Optical light effect made up from a number of bright discs. If the rays from a light source reflects off the surface of a compound lens in a camera, it can generate star-like patterns on the image. Lens flares tend to be a cliché of bad CG imagery, probably because of their short rendering time and flashy appearance.

This is a term that is talking about varying the amount of detail in an object depending on the distance from the object to the camera. Example: A car for a close-up would need to have every little detail modeled into it. Chrome, bumpers, body seams, door handles, etc. But that same car, as seen from a helicopter flying over a highway, might be able to be a simple cube with an image map applied to it.

Level-of-Detail control
The ability to vary the amount of details displayed in a graphics image to improve performance. For instance, at a distance, models can appear as simple 3D figures, but as users zoom in, a more detailed representation is presented.

In 3D graphics different types of lights are distinguished: ambient light, diffuse light, point light, spotlight. There are also different terms used to simulate material properties is illuminated: ambient component, diffuse component, specular component. Incident light at a surface = reflected + scattered + absorbed + transmitted. Light has a major impact of a rendered scene, but can be hard to recreate.

Light source
There are several different sorts of light sources used in 3D graphics to simulate light: ambient, distant, linear, area, and spotlight. Special light effects can be recreated such as volumetric light and glow. With radiosity, an object with a high luminosity value can cast light as well.

Lighting a scene
One of the ingredients of a nice rendering is realistic lighting. It is often good to use one single light source (the key light) doing most of the work, helped out by some additional, less intense lights (fill lights) that illuminates the background of the rendered object to create a smoother look. Try to avoid shadows with edges that are too crisp, since this is unusual in real life due to radiosity.

Lighting Model
This is a model that uses a mathematical formula to decide what will happen when light strikes an object’s surface.

Luminance map generated (normally rendered) individually for each polygon and then blended with the texture map to give the impression of light and shadows falling onto the polygon without having to draw the effect on the texture itself. The advantage of separating the light-map from texture map is that if you should want to create a new "mood" for a scene you can set up new lighting conditions for the scene, re-render the light-maps and apply them to the mesh again, without having to redraw all texture maps.

Linear patterning
The repetitive placement of the active pattern cell along a line, line string, shape, arc, circle, ellipse, or curve element.

LOS has become quite important in modern real-time interactive simulators, especially for military purposes. To cut down on the polygon count and increase rendering performance, programmers are often forced to employ schemes to simplify terrain at large distances. This, however, has the unfortunate drawback of warping the terrain, something that may make a difference for long distance targeting purposes. Because of this, modern terrain rendering algorithms such as ROAM tend to not simplify along the primary LOS.

Local coordinate system
As opposed to the world coordinate system the Local Coordinate System is tied to a specific object. LCS are used, among other reasons, to simplify the representation of complex objects by using several, different LCSes as reference points for the object's vertices. It is also easier to transform the object if you for instance can rotate it around its own "center of gravity" instead of the origin of the World Coordinate System.

Local Coordinates
Every object has its own origin, which is subordinate to the world coordinate system (or other objects that are higher in the hierarchy). Local coordinates are useful for determining positions of subordinate objects.

Local illumination
A mathematical model capable of creating imagery where only direct illumination is considered. Depending on the distance from the lightsource, etc, each surface in the model can be given a color and intensity. This does not include shadows, reflections and radiosity.

Abbreviation for level of detail.

Creating three-dimensional object from two or more two-dimensional shapes and then extruding them along a path.

Laughing out loud

A continuous playback of an animation sequence.

Abbreviation for line of sight.

Low-poly modeling
To model using boundary representation using as few polygons as possible to speed up rendering and processing time. Common style for games, but as game processor engines get better, and computers faster, this is losing ground as an art form.

This is LightWave's built-in scripting language. LScripts can be installed and used just like plug-ins.

This is short for LUMinance ELement, the lumel is a pixel in a lightmap which constitutes the color level in a specific area of the texturemap it is superimposed upon.

The black and white information (brightness, sharpness, and contrast) encoded in a color. The amount of luminance contained in a color is directly proportional to the amount of light intensity.

Luminance map
A map that controls the luminosity channel of a surface.

Much like glow, luminosity is a measure of how much light a surface gives off before any light strikes it. This effect can be used to create an object that gives off its own light.

This tool allows the user to move points in an object as if he or she was using a magnet. It has an area of falloff where the strength of the magnet decreases gradually to 0 giving a soft selection effect.

An attribute that can be added to an object's surface to give it a certain look. Projecting an image so that it covers the surface of an object or images that affect the way an object looks. There are a variety of different maps used for to create specific effects: diffuse maps, bump maps, opacity maps, etc. Maps can be divided into bitmap-dependent texture maps and procedural maps. The latter categories can, in turn be divided into 2D maps and 3D maps.

The process of making one image conform to the size, shape, and/or texture of another image.

There is an underlying material in any given surfacing, even though it might be hidden underneath another texture map. By modifying the properties of a material it can be made to look like wood, plastic, glass, metal etc, (hence the name). The material is applied to the whole object. Also can be referred to just as surface.

Material properties
The different properties of a material such as the ambient component, diffuse component and specular component in the reflection-illumination model.

What is the Matrix? Much more than a mere programming term, or a movie with Keanu Reeves. Matrices form the core of linear algebra and are important tools in most engineering disciplines. In essence a two-dimensional array of numbers, matrices are often used in transforms of different properties, such as rotation, scaling, translation, deformation, and much more.

Memory swapping
The transferring of data back and forth between active RAM memory and disk. When this happens, it can considerably slow down computing tasks such as rendering.

A really hip way of referring to your objects. Object made up from a number of triangular faces.

Mesh complexity
Term for describing the amount of information (amount of vertices, normals, triangles etc) used to create an object. A higher mesh complexity needs more memory and is slower to process

One of the options used with the Subdivide tools. This feature does not divide the polygons, rather it renders the edges of the polygons to be smooth, making the object seem less faceted and cleaner.

Using a pyramid structure of a predefined fixed amount of differently sized bitmaps (original size, original size/2, original size/4, etc) to speed up rendering time by using less detailed textures for distant objects (represented by only a few pixels on the screen), and the full-sized version of the bitmap when the objects is closer to the observer. This way, moiré-pattern can be avoided.

The mirror tool creates an exact mirror image of the selected object. This tool is very useful for any symmetrical object, including faces, cars, and airplanes. This tool literally cuts the modeling time of these objects in half. Can be used to detect vampires.

The process of creating a 3D scene consisting of objects and the applying of mapping to those objects or of posing before a camera, sometimes with no clothes on!

Moiré pattern
Optical pattern created due to aliasing. Usually appears as a swirling pattern along a distant edge.

A special directory, used by some studios, to hold already modeled organic body parts. If you have modeled a good head, hands, ears, feet, etc. there is no reason to model them again. These models are placed in a "morgue" for other modelers to draw from.

Motion blur
The blurring of objects that move while the camera shutter is open, creating the illusion of movement. Motion blur also prevents strobing caused by too-rapid of movement.

Motion Capture
A method used to input live movements into a computer with an external source.

Motion Channel
Motion Channel is generally the same as Animation Channel, but refers only to position, rotation, and scale (i.e., not light intensity.).

Motion Path
The line an object follows while in motion.

There are four basic camera movements: dolly, pan, orbit and truck.

The process of taking a right and left image and combining them with a multiplexing software tool or with a multiplexer to make one stereo 3D image. It's also where you go to see movies, usually has more than six screens.

Applying two (or more) textures on the same face. For example, a polygon can have a texture map resembling a brick wall and then be multi-textured with a light-map to give the illusion of being lit.

Natural light
Light that exists in nature, such as sunlight or moonlight, depends on the time of day, season and location on the Earth. The sunlight a clear day have an RGB value of about R:250 G:255 B:175. For simulating overcast it might be a good idea to add the blue component, whereas a sunset could be a little more orange. As opposed to artificial light, the natural light has only one source (the sun) and can most effectively be recreated using a distant light.

The basic graph element used to represent distinct items (vertices, faces, etc.). A signal coordinate in a grid, or finite element grid point used to describe the structure. A node will lie on each vertex of a finite element, and additional nodes may lie along element edges to define curved element topology.

Non-planar refers generally to a polygon where all points do not reside in the same plane and can occur only with polygons using more than three points. Non-planar polygons can cause erratic rendering errors. As an example, a square piece of cardboard sitting upon a tabletop will become non-planar on all vertices when lifted by a corner. Inherent in manipulation and deformation of a model, non-planar "holes" can appear in the surface consistency of models. Solutions include "tripling" (actually halving the quads diagonally) or tessellating the polygons into triangles. As an example, a triangular piece of cardboard sitting upon a tabletop will remain planar on one vertex when lifted by any corner. Thus, when joined on their vertices, a group of triangles are more robust when deformed.

A normal is a vector that is perpendicular to a mathematical entity, such as a line or a plane. In 3D, the normal can be used to define the direction a polygon is facing, and is used extensively for backface culling and light computation. What is normal??

(National Television Standard Committee). The most common video standard in the United States and Japan. It has a frame-rate of 30 fps. 60 times per second every other scan line is changed, resulting in smoother transitions. Its pixel resolution is 720x486 with a pixel aspect of .9

Non-renderable help-object used in modeling programs to simplify the manipulation of 3D-objects and texture mapping.

Abbreviation for Non-Uniform Rational B-Splines.

American slang. See greeblies.

A model or construction that when placed in a scene will render to represent a thing it represents from the real world.

Object Oriented Graphics
Different from bitmap format, this image type consists of objects that have definite mathematical formulas behind them. These images always print at the maximum quality specified by the printer, unlike bitmapped images that always print at the same quality level. They can also be referred to as “vector graphics”

Omni-directional light
Same as a point light.

The opposite of transparency.

Opacity map (or transparency map)
Makes the surface more or less transparent depending on the pixel intensity (color value) of the opacity map where normally black is transparent and white is opaque.

A 3D graphics API that includes capabilities for 2D imaging. Basically, OpenGL is a set of instructions that can be used by a program to interpret images and display them on the screen. LightWave uses OpenGL for all its displays.

Optical light effect
If the observer (or camera) looks directly at a bright lightsource it may appear to glow. If the light is refracted through a lens or even your own eyelashes (try squinting towards a spotlight!), the light will appear to form star-like patterns.

To travel around a target - more commonly circular, but a comet's orbit can be elliptical.

The world Origin is the absolute center of the LightWave universe. A local Origin is the center of an object. Both are defined by the XYZ coordinates of 0, 0, 0.

A view that displays a parallel projection along one of the major axes. In an orthogonal view, the camera is oriented so it is perpendicular (orthogonal) to specific planes: the Top view faces the XZ plane, the Front view faces the XY plane, and the Right view faces the YZ plane. An orthogonal view eliminates the effect of distance from a viewpoint, which provides a useful means of locating points and objects in 3D space and is particularly helpful when modeling objects in wireframe mode. An orthogonal view is in contrast to a perspective view.

Orthogonal direction
There six different orthogonal directions in a three-dimensional space: up, down, back, forward, left and right

Orthographic projection
Viewing system where the projectors are parallel and therefore doesn't create a perspective with foreshortening.

(Phase Alternating Line). The most common video standard in Europe. It has a framerate of 25 fps. It is interlaced, which means that 50 times per second every other scan line is changed, resulting in smoother transitions. The resolution is 720x576 pixels and the pixel aspect ratio is 1.0667.

To rotate the camera horizontally. As opposed to the orbit movement, the pan rotates the camera around a single axis, as if it where mounted on a tripod.

In a 3D program, a screen that serves many functions such as informing the user of errors, asking for user input, or informing the user of the state a program is currently in. Otherwise known as a window or requester.

A plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the cone or by the locus of points equidistant from a fixed line and a fixed point not on the line.

Technique for assigning values to the edit points as they are spaced along the length of a curve. Can be either uniform parameterization or non-uniform parameterization (chord length). The first edit point on the curve had the value 0.0 (regardless of whether it is uniform or non-uniform) and the following edit points are assigned greater values the closer they lie to the other end.

Also known generally as properties, parameters are the "atomic" elements of a property set whose values determine the behavior of something. A parameter is one degree of freedom. You can set parameters in property editors.

An object that influences the motion of another object in a hierarchy, called the “child”.

The process of creating a hierarchical organization of objects in a scene. In parenting, an object (called the parent object) is "parented" to another object (called the child object). Parenting relationships can be nested to any degree, so that one or more objects are the children of another object, which is in turn the child of another.

2-dimensional objects typically used in large quantities to create effects like rain and explosions.

Passive Polarized 3D glasses
3D glasses made with polarizing filters. Used in conjunction with a view screen that preserves polarized light.

A partial shadow, as in an eclipse, between regions of complete shadow and complete illumination, a fringe region of partial shadow around an umbra.

A traditional art method of creating the illusion of three-dimensional form and distance on a two-dimensional surface. Perspective provides a three-dimensional view of the scene that indicates depth. In a perspective view, objects appear to converge toward a central vanishing point, and objects closer to the camera appear larger than those farther away. A perspective view is in contrast to an orthogonal view.

Perspective projection
Simulating three-dimensionality by using foreshortening that triggers the human perception to interpret a two-dimensional image as if it was three-dimensional. An object is drawn smaller and smaller the further it is from the observer. This is achieved by using a center of projection to which all projectors converge, as opposed to where the projectors are parallel.

Philip Nelson
Lord of the Dance.

Phong Shading
The most frequently used interpolative shading technique used today. It uses a linear combination of three components - the ambient component, the diffuse component and the specular component. The placement of the highlight is less dependant on the underlying polygons as Gouraud shading since Phong shading interpolates the normals on a per-pixel basis instead of interpolating the light intensity based on the distance to the three vertices.

The process of generating computer images that mimic photographs.

The amount that the camera or an object in the scene is tilted up or down. If you nod your head yes, you are rotating your head in the pitch axis.

Pivot Point
A single point, usually in the geo-center of an object that is used for many functions. It is the point that is addressed to locate an object’s position in 3D space. It is also the point around which all rotational moves are made and is the reference point for transformations and scaling.

Short for PIcture ELement, a pixel is the smallest element of computer or video display.

Plane refers to a two-dimensional (i.e., flat and level) surface. Imagine a plane as a piece of glass that is infinitely large, but has no depth.

A plug-in is a program that works with and extends the functionality of LightWave.

A fundamental building element of an object in 3D space with an XYZ location. Point coordinates are the minimum information from which the geometry of an object can be calculated.

Point light
Light source emitting light in all directions (omni-directionally) from a single point in space. It takes six shadow (one in each orthogonal direction) calculations to render shadows generated by a point light, which means that inserting multiple point lights in a scene might slow down rendering time considerably. Point light emanates in all directions, think "light bulb".

Geometric shape in one or many planes. Polygonal modeling consists of using many faces to create the shape. Since polygons in most cases are faceted simplifications of a much smoother shape, they are more or inaccurate, as opposed to the more organic NURBS. The more the tessellation, the higher and the closer the accuracy compared to the desired shape.

A geometric entity composed of one or more connected segments that are treated as single entity.

Abbreviation for Point of View.

Primary colors
There are three primary colors of light: red, green and blue (RGB). Light colors are additive, which means that if these three colors are combined equally, the result is a white light. Black is thus absence of light.

Basic geometric shape used in modeling. Some primitives consist of a combination of different primitives. Cone, box, sphere, tube, torus, and disc are common primitives.

Procedural map
A map (often three-dimensional) generated mathematically instead of using an image. The procedural map does not need texture coordinates. A map that is not based on an image but generates the map using a set of user-customized variables.

Procedural Textures
Mathematically generated textures (2D and 3D). Their advantage is that they are largely independent of the projection type.

Projected shadow
A shadow that falls from an object and projects on a surface.

Projection Map
A mapping procedure that allows the user to apply the map to multiple objects as if they were one.

A polygon with four sides, short for quadrilateral.

This tool causes points to snap to a specific (X, Y, Z) coordinate. This tool is generally used when a lot of precision is required.

Magically delivered full-grown to W. R. Hamilton in 1843, quaternions are mathematical objects consisting of a scalar and a vector which together form a four-dimensional vector space. Although having interesting uses in mathematics, their main use in computer graphics resides in their capability of easily representing 3D rotations. Although impossible to visualize, they suffer from no singularities like Euler angles, and are also easy to smoothly interpolate for keyframe animation (using a mathematical operation called SLERP for Spherical LinEar intERPolation

A more physically correct approach (developed in 1984 by Siegel and Howell) to simulate propagation of light in a virtual environment. It takes into account the fact that light bounces off a surface and creates diffused lighting on the surrounding objects. The scene is divided into a certain amount of triangles that are used to represent the original scene (which speeds up the time-consuming process), and then radiation interaction is calculated using these triangles. As far as visual quality is concerned, the more crucial the part of the scene the denser the triangles must be. This technique creates much more realistically lit environments, however it takes much longer to render due to the massive amount of calculations.

Rail Clone
This tool creates multiple copies of an object that are evenly spaced along one or more user-defined curves.

Rail Extrude
This tool is used to extrude polygons along a specified line or combination of lines. This allows the user to create a shape other than that created from a normal, static extrude.

Rapid Prototyping
The process by which a computer model of a 3D object is turned into a real object. Rapid prototyping methods vary but often involve laying down strata of base material which is then bonded together using a substance like cyanoacrylate (superglue).

The process of, on a per pixel basis, determining what value to assign to the pixels on the screen from a vector based image.

Ray-traced shadow
Shadow created by tracing the light rays from a light source. The ray-traced shadows are more accurate than those created by shadow map, but takes longer time to render and always have crisp edges

Ray tracing
An advanced rendering technique capable of calculating reflections, refractions and shadows.

Raytraced renderings take more time to generate, but have a photorealistic quality. To keep rendering time to the minimum, keep the to the smallest value necessary.

Ray tracing depth (ray recursion limit)
Number of times the light bounces off a surface when ray tracing. Used to create reflections and/or refractions. For example, ray tracing two mirrors facing each other with the ray tracing depth set to 3 will allow the image of the reflected mirror to show the first mirror in it.

Light that bounces off a surface. A mirror is highly reflective, whereas the reflection of a matte rubber surface is insignificant.

Reflection map
Simulates reflections in a surface using the reflection map instead of actually ray tracing the reflected image. This speeds up rendering time, but can also be a give-away if the scene is animated.

Reflection-illumination model
Model used when creating two-dimensional images from three-dimensional meshes. To produce more realistic and convincing images, the reflection model imitates attributes of real-life objects.

When light passes through a transparent material and into a denser or less dense medium the light rays are refracted and change direction. Each material has its own and depending on de density of the material the refraction is more or less evident. Refractions are calculated similarly to reflections using ray tracing.

Refraction index
A value describing the amount of refraction that takes place in a specific transparent material. For vacuum the refraction index is 1.0000, for air 1.0003, for glass approximately 1.5 and for water 1.3333.

Refraction map
An image to control the level of refraction across a surface where dark values indicate a low refractive index and bright ones a high refractive index.

To cause to become, to make, to process. To mathematically generate geometries, algorithms, reflections, etc. Our work would be meaningless without the ability to render. Creating a final image of a model that shows all of the surface properties that have been applied to an object. This process involves adding all colors; bump maps; shading; and other elements that add realism. In a normal 3D program, the user can view the wireframe of the created image. When an image is rendered, the wireframe is covered with the specified colors and properties.

Render pass
A division of a scene according to different aspects (such as highlight, mattes, or shadows) for the purposes of applying specific rendering options. Passes can then be composited during post-production. The default pass is the beauty pass, which includes all objects in the scene. Preset passes include matte, shadow, and highlight passes. You can also define your own passes to include any object you want to be affected by specific rendering properties. Render passes are further divided into partitions.

Rendering pipeline
Description given to the process of creating the rendered images. Some studios have a process by which all the images go through. Some render in passes, one for the base, then the shadows, then the reflections, etc. This process is the pipeline.

The number of picture elements in an image.

A modeling term defining a surface made by rotating a curve around the axis of another curve.

RGB color model
A color model that mixes the three primary colors to produce colors. To create yellow, red and green are mixed without any blue component. The higher the value of the red, green and blue, the clearer the color. Lower RGB values give darker colors, higher gives lighter.

The process of making an object ready for animation. This does not have to be just characters; it is the same for all objects. Rigging involves creation and implementation of bones, hierarchies, clamps, weight maps and sliders.

Right-handed coordinate system
A coordinate system (frequently used in 3D-graphics applications) whose positive Z-axis emerges from the screen towards the user, just like the one used in mathematics, as opposed to the left-handed coordinate system.

Rolling on the floor, laughing.

Rolling on the floor, laughing my ass off.

The amount that a camera is tilted to the left or right. Also known as the bank angle.

A technique in which video or film images are placed in the background of a scene, one frame at a time. You can use these reference images to create your own animation by tracing objects from the images or matching your objects with the images' motion. You can zoom and pan the scene while maintaining perfect registration with the imported background.

Row Interleaved
A format to create 3D video or images in which each row or line of video alternates between the left eye and the right eye (from top to bottom).

Read the Freaking manual (cleaned up for you kiddies!)

Rule-based design
The definition of relationships between objects in the design. Another name used to describe knowledge-based design.

A quantity, such as mass, length, or speed, that is completely specified by its magnitude and has no direction, a one dimensional value.

Device for reading images (from books, photos etc.) into the computer. This is useful for creating realistic textures. With a 3D scanner it is even possible to capture three-dimensional objects and convert them into models. A person whose mother took part in a project created by Dr. Paul Routh and was given ephemerol injections. Some can control minds and cause heads to expolode.

The process of manually dragging the frame advance control slider on the timeline to see or hear its effect on video/audio.

Refers to Solid Drill. Acts just as a drill would, using a 3D object as the drill bit. This tool can be used to take sections out of objects or perform other functions that a drill might.

A seamless texture can be tiled without visible transitions where the bitmap begins and ends. This means that the upper part of the bitmap can be placed next to the lower part of the bitmap (the same goes for the left/right part) forming a pattern that is apparently coherent. Seamless textures have no apparent seams.

Séquential Couleur à Memoire. The television broadcast standard for France, the former USSR, and various eastern European countries. Like PAL, SECAM is based on a 50 Hz power system, but it uses a different encoding process and displays 819 lines interlaced at 50 fields per second. SECAM is not compatible with NTSC or PAL, but conversion between the standards is possible.

Secondary animation
Once the main movements of animation have been applied, this refers to the detail animation step. Hoses bouncing with a robot walking, flab wiggling with a heavyset character, these refer to secondary animation.

Convex volume used to speed up rendering time.

Apparent shadow due to lack of incoming light

Self-illumination (or luminosity)
Allows non-homogene self-illumination of the surface. Some parts can be self-illuminated, some partially self-illuminated, and some not at all) based on the pixel intensity of the self-illumination map.(normally black=left unchanged white=self-illuminated

A session is a single use of an application. A session begins when you first start the application and ends when you exit.

Shaded mode
Shaded mode generally refers to a viewport that has its Rendering Style (Display Options panel or viewport title bar) set to something other than wireframe. These modes show polygon surfaces with some level of shading.

Simulating that an object is lit by a light source.

An area that is not or is only partially lit because of the interception of light by an opaque object between the area and the source of radiation.

Shadow map
Bitmap generated by the rendering engine during a pre-render pass of the lit scene. Generally a shadow map is less precise than a raytraced shadow, but takes less time to render. As opposed to a ray-traced shadow, a shadow map can create shadows with smooth edges. Furthermore, the shadow map is unable to show the color cast by a transparent object. The quality of the shadows in the rendered image depends on the size of the shadow map. The bigger the map the nicer the shadows. Too small shadow map might result in aliased or stairstepped edges. For example, a 256x256 shadow map (65k)is normally sufficient for resolutions of 320x200 and less. If an object is far away from the light source, the shadow map will have to be increased in order to maintain visual quality. If the final rendering is in high-resolution, the shadow map also needs to be hi-res.

Modifying an object by tilting it

Technique that, when rendering or shading, smoothes out the edges between segments making objects appear smoother than their geometry really are.

Soft shadow
A shadow that does not have hard edges.

A set of elements or points satisfying specified geometric postulates: non-Euclidean space. The infinite extension of the three-dimensional region in which all matter exists.

This property determines how shiny (and sometimes wet) an object appears. It represents the highlight that the light creates when shining on an object.

Specular component
Part of the reflection-illumination model. Specular surfaces are capable of reflecting light like a mirror.

Specular map
Replaces the specular component of the reflection-illumination model, thus only visible in an object's surface's highlights.

Specular reflection
The brightest area on a surface, reflecting surrounding light sources, creating highlights.

Spherical Image Map
One of the many methods of applying a texture to a surface. This method applies the texture to an object as it would apply the texture to a sphere. There are many other methods of texturing objects, such as Cubic and Planar image mapping.

Spinning light trick
Trick to create soft shadows with ray tracing. It involves parenting multiple lights to a null and spinning the null.

Spline (Curves)
LightWave uses splines or curved paths between keys while moving items about. When modeling, splines refer to open or closed curves.

Spline Cage
A spline cage is usually a three-dimensional object made up of connected spline curves.

Spline Patching
Spline patching is the process of adding polygons to fill in areas outlined by splines.

A small opaque circle placed in front of a light, usually to remove the a specular hot spot off of an object.

A lightsource emanating light in one direction only, in the shape of a cone.

Staircasing (or stairstepping)
A graphical flaw caused by insufficient resolution. When rendering an object its contours might stand out too crisply from the background and the pixels might be obviously "zig-zagged", or look like stairs. To prevent this, pixels can be blended into their neighbors' colors by anti-aliasing.

When using the drill tool, the stencil option adds the details of the drilling polygon to the polygon being drilled. This creates new geometry on a shape.

Stereoscopic 3D
Two separate photographs taken from slightly different angles that, when compiled, appear three-dimensional.

Stretch Tool
Allows the user to change the dimensioning of an object along a particular axis. Basically, it stretches stuff.

This tool divides any selected polygons with three or four sides into smaller polygons. This makes an object appear smoother, but also makes the model more complex.

Subdivision Surfaces
Subdivision surfaces are a technique to create a smooth curved surface from a coarse polygon mesh. Several different subdivision schemes have been developed since Catmull & Clark first introduced the idea back in 1978. The most well known schemes are the triangle based Loop scheme and Catmull & Clark's original scheme, which is based on quad polygons. Subdivision surfaces moved out to the public in Pixar’s movies, Toy Story 2 and Geri’s Game.

Refers to a modeling mode wherein polygons become a cage that controls an underlying mesh of subdivision surfaces.

Subtractive opacity
Sort of opacity that subtract the background color from the material's color of the transparent object

Super pixel
They are created in a supersampling image. Groups of the superpixels are filtered into the one single pixel that is displayed on the output display.

Generating images at a resolution n times n larger than the display resolution and then filtering the co-called superpixels into the smaller resolution image, creating smooth images with anti-aliasing.

The outer part of an object. The surface attributes can be changed using the Surface panel. Such attributes as name, color, and many other features affect the appearance of an object.

Modifying an object by progressively narrowing it along an axis.

In aiming the camera, the target is the object that is selected for the camera to point toward. The target is in the center of the scene.

Short for Technical Director. Although some TDs don’t wear shorts.

Technical Director
A job in a studio that concerns mainly making rigs. Also to help out the other departments where ever possible. They are the problem solvers.

Increasing the detail level of a polygonal 3D model by increasing its number of polygons, usually triangles . The more triangles, the smoother the shape and subsequently the larger the model. The tessellation can be performed by dividing one triangle into two (or more) smaller ones. By doing this the new, more faceted model can be modified without losing too much of its smoothness.

Normally texture describes the attributes of a surface, for example if it’s coarse, smooth, wrinkled or rough, but it also used with the meaning of texture map. There are textures made up from bitmaps (texture map) and textures generated mathematically (procedural map). The specification of how the surface of an object will look. Textures can be anything from simple, solid colors to complex images representing the surface of the object. The simplest example of a texture is placing a picture on a flat plane. The picture is the texture being applied to the plane.

Texture coordinates
Coordinates used to describe how to map a texturemap onto an object. There are different kinds of techniques to apply the texture: planar, box, cylindrical, spherical and shrink map. Their names indicate how the texture is projected onto the object the mapping coordinates are applied to. The shrink map projection differs from the spherical projection in the way it only has one pole where all seams meets. The modeler can manipulate the texture coordinates to or mirror the texture. The procedural maps do not need texture coordinates.

Texture map
Map wrapped over the surface of an object. The texture map needs to be spaced correctly in U and V direction over the object.

Texture Mapping
The process of projecting a (usually) two-dimensional image onto a three-dimensional face such as a triangle or a quad, texture mapping is a relatively cheap way of adding tremendous detail to a scene without resorting to extremely detailed meshes that take an inordinate amount of memory and time to render.

Repeatedly placing the same texture next to itself on the same surface, creating a pattern from one image. This is achieved by increasing the texture coordinates on a polygon to a value greater than 1. Normally, the entire bitmap is tiled from 0.0 to 1.0 in u- (=x) and v (=y). Tiling textures means placing them next to one and other.

The slider under the Layout viewport representing time in animation.

The act or an instance of transforming. The state of being transformed. A marked change, as in appearance or character, usually, HOPEFULLY for the better.

To move the camera in the viewing plane.

Tweening is the internal process of calculating the animation channel values of all frames between keys.

Twisting a mesh by rotating its vertices non-uniformly along an axis.

Represents a grid line in one direction (normally that of the original curve) of a UV texture map.

A dark area, especially the blackest part of a shadow from which all light is cut off. The completely dark portion of the shadow cast by the earth, moon, or other body during an eclipse.

This command creates single-sided polygons according to the properties of their surface normals. Basically, this tool transforms polygons that share points into a single polygon.

One of the options in the Boolean tool. This option makes an object that is a combination of the two objects. A combination so formed, especially an alliance or confederation of people, parties, or political entities for mutual interest or benefit.

A grid system for identifying points on a surface. The U-direction and V-direction are for the surface, what the X-axis and Y-axis are for the coordinate system.

V (Vertex) Maps
V Maps is an abbreviation for vertex maps. V Maps provide additional information associated with object points (vertices), like weight, UV and morph maps.

Represents a grid line in one direction (normally "up/down") on the surface of an object.

Entity with both magnitude and direction. A three-dimensional vector is written as:
V=(v1, v2, v3) where each component is a scalar.

(pl. vertices) three-dimensional point that is the smallest component in a 3D-mesh.

Vertex count
The number of vertices in a scene. Remember, the higher the mesh complexity the longer the rendering time.

Vertex normal
Even though it is a single point in three dimensional space, its normal can be calculated based on the normal of the face they are describing. The three vertex normals of a single triangle without any neighboring triangles are set to be the same as the polygon's normal. For triangles surrounded by other triangles, the vertex normals are the average of the surrounding face normals.

View frustum
Representing the field of view of the camera, the view frustum is a pyramid volume with the top sheared off. The top of the pyramid represents the viewport of the camera (usually the screen), and is often called the near (or hither) plane, while the bottom is called the far (or yon) plane.

View frustum culling
Removing faces that lie outside the observer's view. Only the faces that is within the view frustum is kept for rendering - speeding up rendering time and helping to maintain a high framerate.

Window area displaying orthogonal or perspective projection in a 3D application. The screen can either contain one big viewport or several smaller, tiled viewports. By simultaneously using several viewports displaying a three-dimensional object from different sides (e.g. top, front, left, perspective), modeling in a virtual 3D environment is made possible.

Versatile Interactive Preview Render window that provides the user with an interactive previewing system.

When selecting, a volume of an object is a 3D representation of the area to be edited. When editing, all of the parts of objects contained within this 3D selection can be edited without changing what lies outside of the selection.

Volumetric fog
Fog that, opposed to ordinary fog, is restricted to fit within a containing volume.

Volumetric light
Light simulating illumination of particles floating in mid-air, thereby making the light cone itself visible.

A tool that rotates an object more in the center than in the outer edge. This tool can be easily related to a tornado, where the wind in the center moves faster than the wind in the outer part of the cone.

Short for VOlume ELement, this term refers to a specific rendering technique common in medical visualization as well as some interactive media. In essence, a voxel is a three-dimensional pixel, that is, a cube, with a specific color.

This command takes the selected points and combines them into one point, a single point that is specified by the last point that is selected.

Short for Work In Progress.

A way of visualizing geometry by drawing lines between its vertices and not shading the surfaces within.

World coordinate system
The coordinate system, normally in three dimensions, used to describe the location in space of a specific point called vertex.

Usually is the axis that is left and right.

To turn about the vertical axis, also known as heading.

Usually is the axis that is up and down.

Coordinate system with the Y-axis pointing upwards.

Usually is the axis that is in and out.

Also called depth buffer, the z-buffer is a two-dimensional matrix of 16- or 32-bit integers with the same dimensions as the screen (or viewport). Whenever a polygon is drawn to the screen, the rasterizer checks the corresponding z-buffer value for each screen coordinate and skips drawing the current pixel if the z value is marked as being closer. This allows for some nice effects such as overlapping 3D models, and completely solves the rendering-order problem.

However, this comes at the price of slower performance and greater memory usage, two factors that have become more or less moot with the proliferation of modern 3D accelerators that tend to support z-buffers in hardware.

Coordinate system with the Z-axis pointing upwards.