Glossary
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## Glossary

### A-Z

Active

  Blender makes a distinction between selected and active. Only one Object or item can be active at any given time, for example to allow visualization of data in buttons.

  An active object is one that is in EditMode, or is immediately switchable to EditMode (usually by TAB). No more than one object is active at any moment. Typically, the most recent selected object is active.

  See Also Selected.

Actuator

  A LogicBrick that acts like a muscle of a lifeform. It can move the object, or also make a sound.

  See Also LogicBrick, Sensor, Controller.

Alpha

  The alpha value in an image denotes opacity, used for blending and antialiasing.

Ambient light

  Light that exists everywhere without any particular source. Ambient light does not cast shadows, but fills in the shadowed areas of a scene.

Anti-aliasing

  An algorithm designed to reduce the stair-stepping artifacts that result from drawing graphic primitives on a raster grid.

AVI

  "Audio Video Interleaved". A container format for video with synchronized audio. An AVI file can contain different compressed video and audio-streams.

Back-buffer

  Blender uses two buffers in which it draws the interface. This double-buffering system allows one buffer to be displayed, while drawing occurs on the back-buffer. For some applications in Blender the back-buffer is used to store color-coded selection information.

Bevel

  Beveling removes sharp edges from an extruded object by adding additional material around the surrounding faces. Bevels are particularly useful for flying logos, and animation in general, since they reflect additional light from the corners of an object as well as from the front and sides.

Bounding box

  A six-sided box drawn on the screen that represents the maximum extent of an object.

Bump map

  A grayscale image used to give a surface the illusion of ridges or bumps. In Blender bumpmaps are called Nor-maps.

Channel

  Some DataBlocks can be linked to a series of other DataBlocks. For example, a Material has eight channels to link Textures to. Each IpoBlock has a fixed number of available channels. These have a name (LocX, SizeZ, enz.) which indicates how they can be applied. When you add an IpoCurve to a channel, animation starts up immediately.

Child

  Objects can be linked to each other in hierarchical groups. The Parent Object in such groups passes its transformations through to the Child Objects.

  See Also Parent.

Clipping

  The removal, before drawing occurs, of vertices and faces which are outside the field of view.

Controller

  A LogicBrick that acts like the brain of a lifeform. It makes decisions to activate muscles (Actuators), either using simple logic or complex Python scripts.

  See Also LogicBrick, Sensor, Python, Actuator.

DataBlock (or "block")

  The general name for an element in Blender's Object Oriented System.

Doppler effect

  The Doppler effect is the change in pitch that occurs when a sound has a velocity relative to the listener. When a sound moves towards the listener the pitch will rise. When going away from the listener the pitch will drop. A well known example is the sound of an ambulance passing by.

Double-buffer

  Blender uses two buffers (images) to draw the interface in. The content of one buffer is displayed, while drawing occurs on the other buffer. When drawing is complete, the buffers are switched.

EditMode

  The mode for making intra-object graphical changes. Blender has two modes for making changes graphically. EditMode allows intra-object changes (moving, scaling rotating, deleting, and other operations on selected vertices of the active object). By contrast, ObjectMode allows inter-object changes (operations on selected objects).

  Switch between EditMode and ObjectMode with Hotkey: TAB.

  See Also ObjectMode, Vertex (pl. vertices).

Extend select

  Adds new selected items to the current selection (SHIFT-RMB).

Extrusion

  The creation of a three-dimensional object by pushing out a two-dimensional outline and giving it height, like a cookie-cutter. It is often used to create 3D text.

Face

  The triangle and square polygons that form the basis for Meshes or for rendering.

Field

  Frames from videos in NTSC or PAL format are composed of two interlaced fields.

FaceSelectMode

  Mode to select faces on an object. Most important for texturing objects. Hotkey: FKEY.

Flag

  A programming term for a variable that indicates a certain status.

Flat shading

  A fast rendering algorithm that simply gives each facet of an object a single color. It yields a solid representation of objects without taking a long time to render. Pressing ZKEY switches to flat shading in Blender.

Fps

  Frames per second. All animations, video, and movies are played at a certain rate. Above ca. 15fps the human eye cannot see the single frames and is tricked into seeing a fluid motion. In games this is used as an indicator of how fast a game runs.

Frame

  A single picture taken from an animation or video.

Gouraud shading

  A rendering algorithm that provides more detail. It averages color information from adjacent faces to create colors. It is more realistic than flat shading, but less realistic than Phong shading or ray-tracing. The hotkey in Blender is CTRL-Z.

Graphical User Interface

  The whole part of an interactive application which requests input from the user (keyboard, mouse etc.) and displays this information to the user. Blender's GUI is designed for an efficient modelling process in an animation company where time equals money. Blender's whole GUI is done in OpenGL.

  See Also OpenGL.

Hierarchy

  Objects can be linked to each other in hierarchical groups. The Parent Object in such groups passes its transformations through to the Child Objects.

Ipo

  The main animation curve system. Ipo blocks can be used by Objects for movement, and also by Materials for animated colors.

IpoCurve

  The Ipo animation curve.

Item

  The general name for a selectable element, e.g. Objects, vertices or curves.

Lathe

  A lathe object is created by rotating a two-dimensional shape around a central axis. It is convenient for creating 3D objects like glasses, vases, and bowls. In Blender this is called "spinning".

Keyframe

  A frame in a sequence that specifies all of the attributes of an object. The object can then be changed in any way and a second keyframe defined. Blender automatically creates a series of transition frames between the two keyframes, a process called "tweening."

Layer

  A visibility flag for Objects, Scenes and 3DWindows. This is a very efficient method for testing Object visibility.

Link

  The reference from one DataBlock to another. It is a "pointer" in programming terminology.

Local

  Each Object in Blender defines a local 3D space, bound by its location, rotation and size. Objects themselves reside in the global 3D space.

  A DataBlock is local, when it is read from the current Blender file. Non-local blocks (library blocks) are linked parts from other Blender files.

LogicBrick

  A graphical representation of a functional unit in Blender's game logic. LogicBricks can be Sensors, Controllers or Actuators.

  See Also Sensor, Controller, Actuator.

Mapping

  The relationship between a Material and a Texture is called the 'mapping'. This relationship is two-sided. First, the information that is passed on to the Texture must be specified. Then the effect of the Texture on the Material is specified.

Mipmap

  Process to filter and speed up the display of textures.

MPEG-I

  Video compression standard by the "Motion Pictures Expert Group". Due to its small size and platform independence, it is ideal for distributing video files over the internet.

ObData block

  The first and most important DataBlock linked by an Object. This block defines the Object type, e.g. Mesh or Curve or Lamp.

Object

  The basic 3D information block. It contains a position, rotation, size and transformation matrices. It can be linked to other Objects for hierarchies or deformation. Objects can be "empty" (just an axis) or have a link to ObData, the actual 3D information: Mesh, Curve, Lattice, Lamp, etc.

ObjectMode

  The mode for making inter-object graphical changes. Blender has two modes for making changes graphically. ObjectMode allows inter-object changes (moving, scaling rotating, deleting and other operations on selected objects). By contrast, EditMode allows intra-object changes (operations on selected vertices in the active object).

  Switch between ObjectMode and EditMode with Hotkey: TAB.

  See Also EditMode.

OpenGL

  OpenGL is a programming interface mainly for 3D applications. It renders 3D objects to the screen, providing the same set of instructions on different computers and graphics adapters. Blender's whole interface and 3D output in the real-time and interactive 3D graphic is done by OpenGL.

Orthographic view

  An orthographic view of an object makes it appear flat and two-dimensional, like a plan or an elevation. All the points of the object are perpendicular to the viewing plane, and are projected in parallel.

  See Also Perspective view.

Oversampling

  See Anti-aliasing.

Overscan

  Video images generally exceed the size of the physical screen. The edge of the picture may or may not be displayed, to allow variations in television sets. The extra area is called the overscan area. Video productions are planned so critical action only occurs in the center safe title area. Professional monitors are capable of displaying the entire video image including the overscan area.

Parent

  An object that is linked to another object, the parent is linked to a child in a parent-child relationship. A parent object's coordinates become the center of the world for any of its child objects.

  See Also Child.

Perspective view

  In a perspective view, the further an object is from the viewer, the smaller it appears.

  See Also Orthographic view.

Pivot

  A point that normally lies at an object's geometric center. An object's position and rotation are calculated in relation to its pivot-point. However, an object can be moved off its center point, allowing it to rotate around a point that lies outside the object.

Pixel

  A single dot of light on the computer screen; the smallest unit of a computer graphic. Short for "picture element."

Plug-In

  A piece of (C-)code loadable during runtime. This way it is possible to extend the functionality of Blender without a need for recompiling. The Blender plugin for showing 3D content in other applications is such a piece of code.

Python

  The scripting language integrated into Blender. Python is an interpreted, interactive, object-oriented programming language.

Quaternions

  Instead of using a three-component Euler angle, quaternions use a four-component vector. It is generally difficult to describe the relationships of these quaternion channels to the resulting orientation, but it is often not necessary. It is best to generate quaternion keyframes by manipulating the bones directly, only editing the specific curves to adjust lead-in and lead-out transitions.

Render

  To create a two-dimensional representation of an object based on its shape and surface properties (i.e. a picture for print or to display on the monitor).

Rigid Body

  Option for dynamic objects in Blender which causes the game engine to take the shape of the body into account. This can be used to create rolling spheres for example.

Selected

  Blender makes a distinction between selected and active objects. Any number of objects can be selected at once. Almost all key commands have an effect on selected objects. Selecting is done with the right mouse button.

  See Also Active, Extend select.

Sensor

  A LogicBrick that acts like a sense of a lifeform. It reacts to touch, vision, collision etc.

  See Also LogicBrick, Controller, Actuator.

Single User

  DataBlocks with only one user.

Smoothing

  A rendering procedure that performs vertex-normal interpolation across a face before lighting calculations begin. The individual facets are then no longer visible.

Transform

  Change a location, rotation, or size. Usually applied to Objects or vertices.

Transparency

  A surface property that determines how much light passes through an object without being altered.

  See Also Alpha.

User

  When one DataBlock references another DataBlock, it has a user.

Vertex (pl. vertices)

  The general name for a 3D or 2D point. Besides an X,Y,Z coordinate, a vertex can have color, a normal vector and a selection flag. Also used as controlling points or handles on curves.

Vertex array

  A special and fast way to display 3D on the screen using the hardware graphic acceleration. However, some OpenGL drivers or hardware doesn't support this, so it can be switched off in the InfoWindow.

Wireframe

  A representation of a three-dimensional object that only shows the lines of its contours, hence the name "wireframe."

X, Y, Z axes

  The three axes of the world's three-dimensional coordinate system. In the FrontView, the X axis is an imaginary horizontal line running from left to right; the Z axis is a vertical line; and Y axis is a line that comes out of the screen toward you. In general, any movement parallel to one of these axes is said to be movement along that axis.

X, Y, and Z coordinates

  The X coordinate of an object is measured by drawing a line that is perpendicular to the X axis, through its centerpoint. The distance from where that line intersects the X axis to the zero point of the X axis is the object's X coordinate. The Y and Z coordinates are measured in a similar manner.

Z-buffer

  For a Z-buffer image, each pixel is associated with a Z-value, derived from the distance in 'eye space' from the Camera. Before each pixel of a polygon is drawn, the existing Z-buffer value is compared to the Z-value of the polygon at that point. It is a common and fast visible-surface algorithm.

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