Posted on June 24, 2017, 10:11 p.m. by Ganonmaster • Last updated on Sept. 22, 2020, 2:08 p.m.
This page describes some frequently used terms used in 3d Modeling. Come across a word that you've never seen before? There's a good chance you may find a definition here.
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 armatures, skeletons or splines. The most common 3D objects are geometric objects, which can be classified according to whether they are polygon meshes, curves, proxy objects, or empties.
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 Anti-aliasing.
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.
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.
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.
API, application programming interface
An API is a set of clearly defined methods of communication between various software components. An API can be used to develop new software, like addons for the existing software. For example, Maya and Blender both offer API's that allow users to automate/write scripts to perform tedious tasks.
See Bone Hierarchy.
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. 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).
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.
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.
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.
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.
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.
A method of eliminating sharp edges from objects by extending an object’s faces.
Bones can be arranged to build a Bone Hierarchy, also called a Skeleton or Armature. 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. Bones are often bound to a model through skin weights.
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.
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.
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.
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.
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.
A type of texture/image/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). Bump maps are often used in videogames, as they make it easy to add a lot of detail without sacrificing game performance. See also, Displacement Map.
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. In 3D terms, the camera is the conduit through which your objects and scenes are turned into still images or animations.
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.
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.
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.
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”. Together, they form a hierarchy.
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. Also used to refer to the visible intersecting of models in an undesirable way.
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. For example, an Xbox Kinect camera is capable of generating a point cloud based on the 2D footage that it captures.
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, MP4, WebM, etc. The CODEC can control image quality, and can control the file size given to the video file. First, ab artists uses a codec to squeeze more sound and video into less file space. These smaller, compressed files take less time to upload and download over the internet. Then, your computer uses a codec to expand these files back to their original size and replay them on your screen.
When the color from one surface reflects onto another surface.
An technique of combining two images by replacing one color of the destination image by the corresponding pixels of the source image. Commonly also known as green screening. Film your actors in front of a bright green background and then Color Key that bright green background. You can then easily replace the green background with any scene you want.
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. In 3D terms this usually refers to applying additional image effects to a rendered image.
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.
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.
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.
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.
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. By default, Blender uses "Blender Units", but it can be configured to use metric or imperial units. If you plan on exchanging files between different programs, the units you use are important for keeping the size of an object consistent between programs.
Same as a Z-Buffer.
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.
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.
A type of texture/image/map. Also known as a "color map" or "albedo map". Basically giving the illusion of being painted onto the surface. Generally, when you talk about the "texture" in an application, this is the image actually referred to.
A measure of spatial extent, especially width, height, or length.
Directional Light A light with color, intensity and direction. All rays emitted from a distant light are parallel, and therefore it has no obvious source.
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. Adversely affects performance and takes longer to render.
Ways of displaying objects in a viewport. Display types are available only for geometry views. The available display types in most 3d suites are Bounding Box, Wireframe, Solid, Shaded Solid and Textured Solid. Display types do not determine the quality of the final render.
Abbreviation for depth of field.
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. This is usually only relevant for print media. Images that are rendered on a screen usually don't need more than a dpi of 72. Higher dpi values are only relevant for print media.
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/vertices on a polygon.
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.
Map often used to simulate (faking) reflection of the surrounding world without using ray tracing.
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.
Creating a three-dimensional object from a two-dimensional shape by adding a third dimension to it.
Face The shape made up by the bounding point making a polygon. Faces can have as many vertices as wanted.
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.
Field of View
(FOV) The angle of the view frustum. The wider the FOV, the more you see of the scene.
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.
Shading technique where all individual faces in a mesh are assigned a single color value based on the orientation of their face normals.
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.
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. Often used in videogames, especially on the Nintendo 64
Figure positioning by joint angle specification. Like posing a toy action figure. You determine the angle at which the root bone is rotated at, and all child bones will rotate with it, relative to the parent.
FPS stands for Frames per Second. This is the main a unit of measure that is used to describe graphics and video performance. See also, frame-rate.
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.
The speed at which a frame of animation is shown, usually expressed in frames per second. The higher the frame rate, the smoother the animation. However, the higher the frame rate, the more rendering power is required. Most videos and movies are projected at 24 frames per second.
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. 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.
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.
Glossiness 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.
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.
Goal 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 see, IK/Inverse Kinematics)
Graphical User Interface, GUI
The graphical interpreter between man and computer allows a more intuitive interaction with the computer. Technically, every action on your computer can be performed without a GUI, if you simply type all the necessary commands into the computer. But knowing all the commands is less convenient than just randomly pressing buttons. That's why all the programs you use on your computer have a GUI. Windows and Mac have a GUI and a lot of the programs you use every day on your computer have too. 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.
Halo Optical light effect that forms concentric circles around the center of a lightsource. Often clearly visible around street lights after a rainy day. Also, a pretty cool guy.
Any element that is not shown in the current rendering of the scene but still exists.
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.
The position of the color in the spectrum that describes the tone or tint of a color, such as red, yellow, or blue.
Image Map, Texture
An image that is applied to an object's surface.
Light that bounces of one surface and illuminates another surface.
The strength at which the light source illuminate objects in the scene.
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.
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. This is useful for example, when animating characters shaking hands or grabbing onto an object. You only have to move the endpoint (the hands), and the IK constraints automatically calculate the positions of the elbow and shoulder. With FK (Forward kinematics), you would have to animate each joint individually, making IK the better choice for this type of animation.
Standard view in a 3D design where the top, front, and right side faces of a cube are equally inclined to the screen surface.
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.
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.
Either a way of deforming object using a lattice or a way of creating outlined geometry.
Layer 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.
Part of the camera determining the optical characteristics of the image, such as wide angle, fish eye and depth of field.
Short for 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. This technique is often used in videogames to help rendering performance.
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. JJ Abrams is a director known for his overuse of lens flares.
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.
This is a model that uses a mathematical formula to decide what will happen when light strikes an object’s surface.
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.
A continuous playback of an animation sequence.
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 engines get better, and computers faster, more complex shapes can be rendered there as well. Low-poly models are still very useful for unseen geometry like collision models or different LODs.
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.
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.
An attribute or image that can be applied 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.
A material defines the appearance of (part of) an object. By modifying the properties of a material it can be made to look like wood, plastic, glass, metal etc, (hence the name).
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.
Mesh A way of referring to your model objects. Object made up from a number of triangular faces.
Term for describing the amount of information (amount of vertices, normals, triangles, quads etc) used to create an object. A higher mesh complexity needs more memory and is slower to process.
Mirror Mirror tools an exact mirror image of the selected object. This tool is very useful for modeling any symmetrical object, including characters, faces, cars, and airplanes. This tool literally cuts the modeling time of these objects in half.
Modeling The process of creating a 3D scenes and/or objects.
The blurring of objects that move while the camera shutter is open, creating the illusion of movement.
Motion Capture, Performance Capture
A method used to input live movements into a computer with an external source. For example, capturing someone/yourself performing movements in real life, and then applying those movements to your 3D character.
The line an object follows while in motion.
The basic graph element used to represent distinct items. 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.
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 primarilyfor backface culling and light computation.
A model or construction that when placed in a scene will render to represent a thing it represents from the real world.
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. This map can often be found on the alpha channel of a diffuse map or bump map.
To move around a target in a circular way.
The world Origin is the absolute center of your scene. 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.
Viewing system where the projectors are parallel and therefore doesn't create a perspective with foreshortening.
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.
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.
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.
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.
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.
A single point, usually in the 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.
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 an existing/larger program. Aka Addon.
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.
Light source emitting light in all directions (omni-directionally) from a single point in space. 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. The more the tessellation, the higher and the closer the accuracy compared to the desired shape.
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.
Mathematically generated textures (2D and 3D). Their advantage is that they are largely independent of the projection type.
A polygon with four sides, short for quadrilateral. Quads are often preferred in character modeling because they can be subdivided/tessellated with relatively little performance loss, thanks to libraries such as OpenSubDiv.
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 difficult to visualize, they do not suffer from Gimbal Lock, and are also easy to smoothly interpolate for keyframe animation.
An advanced rendering technique capable of calculating reflections, refractions and shadows. Raytraced renderings take more time to generate, but have a photorealistic quality.
Light that bounces off a surface. A mirror is highly reflective, whereas the reflection of a matte rubber surface is insignificant.
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.
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.
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.
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 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.
The amount that a camera is tilted to the left or right. Also known as the bank angle.
A quantity, such as mass, length, or speed, that is completely specified by its magnitude and has no direction, a one dimensional value.
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.
Simulating that an object is lit by a light source.
Skeleton See Bone Hierarchy.
Technique that, when rendering or shading, smoothes out the edges between segments making objects appear smoother than their geometry really are.
This property determines how shiny (and sometimes wet) an object appears. It represents the highlight that the light creates when shining on an object.
The brightest area on a surface, reflecting surrounding light sources, creating highlights.
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.
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.
Increasing the detail level of a polygonal 3D model by increasing its number of polygons, usually triangles or quads. 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.
Coordinates used to describe how to map a texturemap onto an object.
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 that represents the time in animation.
The act or an instance of transforming. The state of being transformed. A marked change, as in appearance or character.
Tweening is the internal process of calculating the animation channel values of all frames between keys.
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.
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.
The number of vertices in a scene. Remember, the higher the mesh complexity the longer the rendering time.
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.
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.
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.
Fog that, opposed to ordinary fog, is restricted to fit within a containing volume.
Light simulating illumination of particles floating in mid-air, thereby making the light cone itself visible.
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. For example, the worlds of Minecraft are made up of voxels.
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.
Yaw 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.
Z-buffer 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.
Coordinate system with the Z-axis pointing upwards.