user: What is Glossary and how is it used in Blender Python scripting?

assistant: to be saved in a blend-file,
    even when no [Real User](#term-Real-User) is using the object.
    Objects that are not used by any Data User are not included in saved blend-files.

Field of View
:   The area in which objects are visible to the camera. Also see [Focal Length](#term-Focal-Length).

Fireflies
:   Rendering artifacts encountered with path tracing resulting from
    improbable samples that contribute very high values to pixels.

FK

Forward Kinematics
:   The process of determining the movement of interconnected segments or bones of
    a body or model in the order from the parent bones to the child bones.
    Using forward kinematics on a hierarchically structured object, you can move
    the upper arm then the lower arm and hand go along with the movement.
    Without forward kinematics the lower arm and hand would disconnect from
    upper arm and would move independently in space.

    See also [Inverse Kinematics](#term-Inverse-Kinematics).

Focal Length
:   The distance required by a lens to focus collimated light.
    Defines the magnification power of a lens. Also see [Field of View](#term-Field-of-View).

Frame Types
:   In video compression, a frame can be compressed by several different algorithms.
    These algorithms are known as *picture types* or *frame types*
    and there are three major types: **I**, **P**, and **B** frames.

    I‑frames
    :   The least compressible but don’t require other video frames to decode.

    P‑frames
    :   Use data from previous frames to decompress and are more compressible than I‑frames.

    B‑frames
    :   Use both previous and forward frames for data reference to get the highest amount of compression.

Gamma
:   An operation used to adjust the brightness of an image.

    See also [Gamma correction](https://en.wikipedia.org/wiki/Gamma_correction) on Wikipedia.

Geodesic
:   Relating to the shortest possible path between two points on a curved surface.

Geometric Center
:   The mean average of the positions of all vertices making up the object.

Gimbal
:   A pivoted support that allows the rotation of an object about a single axis.

    See also [Gimbal](https://en.wikipedia.org/wiki/Gimbal) on Wikipedia.

Gimbal Lock
:   The limitation where axes of rotation can become aligned,
    losing the ability to rotate on an axis (typically associated with [Euler Rotation](#term-Euler-Rotation)).

    - See also [Gimbal lock](https://en.wikipedia.org/wiki/Gimbal_lock) on Wikipedia.
    - See also [Gimbal lock](https://blender.stackexchange.com/questions/469) on Stack Exchange.

Global Illumination
:   A superset of [Radiosity](#term-Radiosity) and ray tracing. The goal is to compute all possible light interactions
    in a given scene, and thus, obtain a truly photorealistic image.
    All combinations of diffuse and specular reflections and transmissions must be accounted for.
    Effects such as color bleeding and caustics must be included in a global illumination simulation.

Global Space
:   See [World Space](#term-World-Space).

Glossy Map
:   See [Roughness Map](#term-Roughness-Map).

HDRI

High Dynamic Range Image
:   A set of techniques that allow a far greater dynamic range of exposures than normal digital imaging techniques.
    The intention is to accurately represent the wide range of intensity levels found in real scenes,
    ranging from direct sunlight to the deepest shadows.

    See also [HDRI](https://en.wikipedia.org/wiki/HDRI) on Wikipedia.

Head
:   A subcomponent of a [Bone](#term-Bone). The point of rotation for the bone
    has X, Y, and Z coordinates measured in the [Local Space](#term-Local-Space) of the [Armature](#term-Armature) object.
    Used in conjunction with the [Tail](#term-Tail) to define the local Y axis of the bone
    in [Pose Mode](#term-Pose-Mode). The larger of the two ends when displayed as an [Octahedron](#term-Octahedron).

Hue
:   A shade of light out of the color spectrum.

IK

Inverse Kinematics
:   The process of determining the movement of interconnected segments or bones of
    a body or model in the order from the child bones to the parent bones.
    Using inverse kinematics on a hierarchically structured object, you can move
    the hand then the upper and lower arm will automatically follow that movement.
    Without inverse kinematics the hand would come off the model
    and would move independently in space.

    See also [Forward Kinematics](#term-Forward-Kinematics).

Interpolation
:   The process of calculating new data between points of known value, like [Keyframes](#term-Keyframe).

IOR

Index of Refraction
:   A property of transparent materials.
    When a light ray travels through the same volume it follows a straight path.
    However, if it passes from one transparent volume to another, it bends.
    The angle by which the ray is bent can be determined by the IOR of the materials of both volumes.

Keyframe
:   A frame in an animated sequence drawn or otherwise constructed directly by the animator.
    In classical animation, when all frames were drawn by animators,
    the senior artist would draw these frames, leaving the “in between” frames to an apprentice.
    Now, the animator creates only the first and last frames of a simple sequence (keyframes);
    the computer fills in the gap.

Keyframing
:   Inserting [Keyframes](#term-Keyframe) to build an animated sequence.

Lattice
:   A type of object consisting of a non-renderable three-dimensional grid of vertices.

    See also [Lattice Modifier](../modeling/modifiers/deform/lattice.xhtml).

Light Bounces
:   Refers to the reflection or transmission of a light ray upon interaction with a material.
    See also [Light Paths](../render/cycles/render_settings/light_paths.xhtml).

Local Space
:   A 3D coordinate system that originates (for Objects) at the [Object Origin](#term-Object-Origin).
    or (for Bones) at the [Head](#term-Head) of the [Bone](#term-Bone).

    Compare to [World Space](#term-World-Space).

Luminance
:   The intensity of light either in an image/model channel,
    or emitted from a surface per square unit in a given direction.

Manifold
:   Manifold meshes, also called ‘water-tight’ meshes, define a closed non-self-intersecting volume
    (see also [Non-manifold](#term-Non-manifold)). A manifold mesh is a mesh in which the structure of the connected
    faces in a closed volume will always point the normals (and their surfaces) to the outside
    or to the inside of the mesh without any overlaps. If you recalculate those normals,
    they will always point at a predictable direction (to the outside or to the inside of the volume).
    When working with non-closed volumes, a manifold mesh is a mesh in which
    the normals will always define two different and non-consecutive surfaces.
    A manifold mesh will always define an even number of non-overlapped surfaces.

MatCap
:   Stands for “material capture”, using an image to represent a complete material
    including lighting and reflections.

Matte

Mask
:   A grayscale image used to include or exclude parts of an image.
    A matte is applied as an [Alpha Channel](#term-Alpha-Channel),
    or it is used as a mix factor when applying [Color Blend Modes](#term-Color-Blend-Modes).

Mesh
:   Type of object consisting of [Vertices](#term-Vertex), [Edges](#term-Edge) and [Faces](#term-Face).

Micropolygons
:   A polygon roughly the size of a pixel or smaller.

MIP

Mip-map

Mip-mapping
:   ‘MIP’ is an acronym of the Latin phrase ‘multum in parvo’, meaning ‘much in little’.
    Mip-maps are progressively lower resolution representations of an image,
    generally reduced by half squared interpolations using [Anti-Aliasing](#term-Anti-Aliasing).
    Mip-mapping is the process used to calculate lower resolutions of
    the same image, reducing memory usage to help speed visualization, but increasing
    memory usage for calculations and allocation. Mip-mapping is also a process
    used to create small anti-aliased samples of an image used for texturing.
    The mip-mapping calculations are made by CPUs, but modern graphic processors
    can be selected for this task and are way faster.

MIS

Multiple Importance Sampling
:   A process of estimating the direction of light rays to improve sampling quality.

    See [Multiple Importance Sampling](../render/cycles/optimizations/reducing_noise.xhtml#render-cycles-reducing-noise-mis) and
    also [Importance sampling](https://en.wikipedia.org/wiki/Importance_sampling) on Wikipedia.

Modifiers
:   A non-destructive operation that is applied on top of some sort of data.

Motion Blur
:   The phenomenon that occurs when we perceive a rapidly moving object.
    The object appears to be blurred because of our persistence of vision.
    Simulating motion blur makes computer animation appear more realistic.

Multisampling
:   Rendering multiple samples per pixel, for [Anti-Aliasing](#term-Anti-Aliasing).

N-gon
:   A [Face](#term-Face) that contains more than four [Vertices](#term-Vertex).

NDOF

3D Mouse
:   A general term used to describe a 3D mouse, or any input devices which supports
    more degrees of freedom than a conventional 2D input device, see: [Touchpad](../getting_started/configuration/hardware.xhtml#hardware-ndof).

Non-manifold
:   Non-Manifold meshes essentially define geometry which cannot exist in the real world.
    This kind of geometry is not suitable for several types of operations,
    especially those where knowing the volume (inside/outside) of the object is important
    (refraction, fluids, Boolean operations, or 3D printing, to name a few).
    A non-manifold mesh is a mesh in which the structure of
    a non-overlapped surface (based on its connected faces) will not determine
    the inside or the outside of a volume based on its normals, defining
    a single surface for both sides, but ended with flipped normals.
    When working with non-closed volumes, a non-manifold mesh will always
    determine at least one discontinuity in the normal directions, either
    by an inversion of a connected loop, or by an odd number of surfaces.
    A non-manifold mesh will always define an odd number of surfaces.

    There are several types of non-manifold geometry:

    - Some borders and holes (edges with only a single connected face), as faces have no thickness.
    - Edges and vertices not belonging to any face (wire).
    - Edges connected to three or more faces (interior faces).
    - Vertices belonging to faces that are not adjoining (e.g. two cones sharing the vertex at the apex).

    See also: [Select Non-Manifold](../modeling/meshes/selecting/all_by_trait.xhtml#bpy-ops-mesh-select-non-manifold) tool.

Nonlinear Animation
:   Animation technique that allows the animator to edit motions as a whole,
    not just the individual keys. Nonlinear animation allows you to combine,
    mix, and blend different motions to create entirely new animations.

Normal
:   The normalized vector perpendicular to a surface.

    Normals can be assigned to vertices,
    faces and modulated across a surface using [Normal Mapping](#term-Normal-Mapping).

    See also [Normals](https://en.wikipedia.org/wiki/Normal_(geometry)) on Wikipedia.

Normal Mapping
:   Is similar to [Bump Mapping](#term-Bump-Mapping), but instead of the image being a grayscale heightmap,
    the colors define in which direction the normal should be shifted,
    the three color channels being mapped to the three directions X, Y and Z.
    This allows more detail and control over the effect.

NURBS

Non-uniform Rational Basis Spline
:   A computer graphics technique for generating and representing curves and surfaces.

Object
:   Container for a type (mesh, curve, surface, meta-ball, text, armature,
    lattice, empty, camera, light) and basic 3D transform data ([Object Origin](#term-Object-Origin)).

Object Center

Object Origin
:   A reference point used to position, rotate, and scale an [Object](#term-Object)
    and to define its [Local Space](#term-Local-Space) coordinates.

Octahedron
:   An eight-sided figure commonly used to depict the [Bones](#term-Bone) of an [Armature](#term-Armature).

OpenGL
:   The graphics system used by Blender (and many other graphics applications)
    for rendering 3D graphics, often taking advantage of hardware acceleration.

    See also [OpenGL](https://en.wikipedia.org/wiki/OpenGL) on Wikipedia.

Operator
:   An executable action that is completed the moment they’re initiated.
    See [Operators](../interface/operators.xhtml) as described in the user interface section.

Overscan
:   The term used to describe the situation.
    when not all of a televised image is present on a viewing screen.

    See also [Overscan](https://en.wikipedia.org/wiki/Overscan) on Wikipedia.

Panel
:   A user interface element that contains buttons.
    Panels are collapsible to hide there contents and can often be rearranged.
    See [Panels](../interface/window_system/tabs_panels.xhtml#bpy-types-panel) as described in the user interface section.

Parent
:   An [Object](#term-Object) that affects its [Child](#term-Child) objects.

Parenting
:   Creating a [Parent](#term-Parent)-[Child](#term-Child) relationship between two [objects](#term-Object).

Particle System
:   Technique that simulates certain kinds of fuzzy phenomena,
    which are otherwise very hard to reproduce with conventional rendering techniques.
    Common examples include fire, explosions, smoke, sparks, falling leaves, clouds, fog, snow, dust,
    meteor tails, stars, and galaxies, or abstract visual effects like glowing trails, magic spells.
    Also used for things like fur, grass or hair.

Phong
:   Local illumination model that can produce a certain degree of realism in three-dimensional
    objects by combining three elements: diffuse, specular and ambient for each considered point on a surface.
    It has several assumptions – all lights are points, only surface geometry is considered,
    only local modeling of diffuse and specular, specular color is the same as light color,
    ambient is a global constant.

Pivot Point
:   The pivot point is the point in space around which all
    rotation, scaling and mirror transformations are centered.

    See also the [Pivot Point](../editors/3dview/controls/pivot_point/index.xhtml) docs.

Pixel
:   The smallest unit of information in a 2D raster image,
    representing a single color made up of red, green, and blue channels.
    If the image has an [Alpha Channel](#term-Alpha-Channel), the pixel will contain a corresponding fourth channel.

Point Cloud
:   A list of points in 3D space.

Pole
:   [Vertex](#term-Vertex) where three, five, or more edges meet.
    A vertex connected to one, two, or four edges is not a pole.

Pose Bone
:   Pose-specific properties of a [Bone](#term-Bone), such as its location /
    rotation / scale relative to the [Armature](#term-Armature)’s rest pose. Its
    properties are stored on the [Object](#term-Object), and thus can be different for
    each user of the Armature. The Pose Bone also stores constraints.

Pose Mode
:   Used for [Posing](#term-Posing), [Keyframing](#term-Keyframing), [Weight Painting](#term-Weight-Painting),
    [Constraining](#term-Constraint) and [Parenting](#term-Parenting) the [Bones](#term-Bone) of an [Armature](#term-Armature).

Posing
:   Moving, Rotating and Scaling the [Pose Bones](#term-Pose-Bone) of an
    [Armature](#term-Armature) to achieve an aesthetically pleasing pose for a
    character.

PPI

Pixels Per Inch
:   A physical measurement for the number of individual pixels that can be placed in a line span of one inch.

    This term is sometimes used interchangeably with [DPI](#term-DPI).

Premultiplied Alpha
:   See [Alpha Channel](#term-Alpha-Channel).

Primaries
:   In color theory, primaries (often known as primary colors) are the abstract lights,
    using an absolute model, that make up a [Color Space](#term-Color-Space).

Primitive
:   A basic object that can be used as a basis for modeling more complicated objects.

Procedural Texture
:   Computer generated (generic) textures that can be configured via different parameters.

Projection
:   In computer graphics, there are two common camera projections used.

    Perspective
    :   A *perspective* view is geometrically constructed by taking a scene in 3D and placing an observer
        at point *O*. The 2D perspective scene is built by placing a plane (e.g. a sheet of paper)
        where the 2D scene is to be rendered in front of point *O*, perpendicular to the viewing direction.
        For each point *P* in the 3D scene a *PO* line is drawn, passing by *O* and *P*.
        The intersection point *S* between this *PO* line and the plane is the perspective projection
        of that point. By projecting all points *P* of the scene you get a perspective view.

    Orthographic
    :   In an *orthographic* projection,
        you have a viewing direction but not a viewing point *O*. The line is then drawn
        through point *P* so that it is parallel to the viewing direction. The intersection
        *S* between the line and the plane is the orthographic projection of the point *P*.
        By projecting all points *P* of the scene you get the orthographic view.

Proxy
:   For video editing, a proxy is a smaller version of the original file,
    typically using an optimized video codec and lower resolution version (faster to load)
    that stands in for the main image or video.

    When proxies are built, editing functions like scrubbing and scrolling and compositing is much
    faster but gives lower resolution and slightly imprecise result.

Quad

Quadrilateral

Quadrangle
:   [Face](#term-Face) that contains exactly four [Vertices](#term-Vertex).

Quaternion

Quaternion Rotation
:   Rotation method where rotations are defined by four values (X, Y, Z, and W).
    X, Y, and Z also define an [Axis](#term-Axis), and W an angle,
    but it i