Glossary

G4D for artist

2D

2D texture map

A texture map with 2 dimensions, typically indexed by UV coordinates.

2D vector

A 2 dimensional vector, a common data type in rasterization algorithms, 2D computer graphics, graphical user interface libraries.

3D

3D graphics pipeline

A graphics pipeline taking 3D models and producing a 2D bitmap image result.

3D scene

A collection of 3D models and lightsources in world space, into which a camera maybe placed, describing a scene for 3d rendering.

A

Additive blending

A compositing operation where, d s t = d s t + s r c {\displaystyle dst=dst+src} , ,  without the use of an alpha channel, used for various effects. Also known as linear dodge in some applications.

Anti-aliasing

Methods for filtering and sampling to avoid visual artefacts associated with the uniform pixel grid in 3d rendering.

Ambient light

The light entering a region from a wide range of directions,used to avoid needing an exact solution to the rendering equation

Array texture

A form of texture map containing an array of 2D texture slices selectable by a 3rd 'W' texture coordinate; used to reduce state changes in 3d rendering.

Alpha channel

An additional image channel (e.g. extending an RGB image) or standalone channel controlling Alpha blending.

AO

Ambient occlusion, an approximation to global illumination.

 

 

B

Billboard

A texture map rendered with one or two of its axes parallel to the plane of the screen as a 3D sprite, typically used for vegetation

Bit depth

The number of bits per pixel, sample, or texel in a bitmap image (holding one or mode image channels, typical values being 4,8,16,24,32

Bitmap

A bitmap (or raster graphic) is a digital image composed of a matrix of dots. When viewed at 100%, each dot corresponds to an individual pixel on a display. In a standard bitmap image, each dot can be assigned a different color. Together, these dots can be used to represent any type of rectangular picture.

Bit plane

A format for bitmap images storing 1 bit per pixel in a contiguous 2d array; Several such parallel arrays combine to produce a higher bit depth image. Opposite of packed pixel format.

Blend operation

A render state controlling alpha blending, describing a formula for combining source and destination pixels.

C

Camera

In 3D video games, a virtual camera system aims at controlling a camera or a set of cameras to display a view of a 3D virtual world. A virtual camera from which rendering is performed, also sometimes referred to as 'eye'.

Camera space

A space with the camera at the origin, aligned with the viewer's direction, after the application of the world transformation and view transformation.

Color channels

The set of channels in a bitmap image representing the visible color components, i.e. distinct from the alpha channel or other information.

CLUT - color look-up table

A table of RGB color values to be indexed by a lower bit (4-8bits) depth image, a form of vector quantization.

CMYK - color model

Short for Cyan-Magenta-Yellow-Black. CMYK is a color model in which all colors are described as a mixture of four process colors. CMYK is a subtractive color model and used in offset printing for full-color documents. Because such printing uses inks of four basic colors, it is often called four-color printing.

Color printing typically uses ink of four colors: cyan, magenta, yellow and key (black). When CMY “primaries” are combined at full strength; the resulting “secondary” mixtures are red, green and blue. Mixing all three gives black.

 

D

Depth buffer

A bitmap image holding depth values (either a Z buffer or a W buffer), used for visible surface determination, during rasterization of 3D scene’s

Depth map

A bitmap image or texture map holding depth values. Similar to a height map or displacement map, but usually associated with a projection.

Depth value

A value in a depth map representing a distance perpendicular to the space of an image.

Displacement mapping

A method for adding detail to surfaces by subdivision and displacement of the resulting vertices form a height map.

E

Edge vector

A vector between 2 position vertices in a polygon or polygon mesh, along an edge

F

G

Geometry

Typically used to refer to vertex & rendering primitive connectivity information (distinct from materials and textures).

G-buffer

A screen space representation of geometry and material information, generated by an intermediate rendering pass in deferred shading rendering pipelines.

 

 

Green screen

Chroma key compositing, or Chroma keying, is a special effects or technique for layering two images or video streams together based on color hues (Chroma range). There are different colors to use to achieve these techniques but the most common are Blue, Green and red. The last mentioned color is however rare.

H

 

HDR

High dynamic range imaging, an image format using floating-point values.

 

 

I

Impostor

A dynamically rendered Billboard texture map used to stand in for geometry in the distance. A form of level of detail optimization.

Image channel

A single component (referred to as a channel) of a bitmap image; one of multiple components per pixel, e.g. for RGB or YUV color space, or additional channels for alpha blending

Image format

A specific way of representing a bitmap image in memory, also refers to image file formats.

Image generation

Almost the same as rendering; taking a 3D scene (or other form of encoded data) and producing a bitmap image result.

J

K

L

Light vector

In shading calculations, a 3D unit vector representing the direction of incident light onto a model's surface.

M

Modelling (primitive)

Basic elements from which 3D models and 3D scenes are composed. Also known as a Geometric primitive.

Model transformation matrix

A transformation matrix producing world coordinates from a 3D model's local coordinates.

 

d s t = d s t ∗ s r c {\displaystyle dst=dst*src} .

N

O

Occlusion query

A command passed to a Graphics processing unit requesting the testing of bounding volume geometry against the depth buffer to determine if any contents in the potentially visible set; used for hardware accelerated occlusion culling.

P

Pixel

In digital imaging, a pixel dots or picture element is a physical point in a raster image, a pixel is it is the smallest controllable element of a picture represented on a screen. Each pixel is therefore a sample of an original image. The more samples is provide the more accurate representations of the original. In color image systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black.

Packed pixel format

Image format where the image channels are interleaved contiguously in memory, possibly containing multiple channels within single machine words, equivalent to an array of structures for bitmap data. Contrasts with planar image formats.

Parameter gradient

The derivative of a vertex attribute with respect to screen space coordinates during rasterization, used for interpolation across a rendering primitive surface.

Planar image format

Image format where the image channels (or even bits) for a single pixel is separated into several parallel arrays, equivalent to a structure of arrays for bitmap data.

Polygon mesh

A 3D model consisting of vertices connected by polygon primitives.

Post production

Post production is part of the process of filmmaking and video production. It occurs in the making of motion pictures, television programs, radio programs, advertising, audio recordings, photography, and digital art. It is a term for all stages of production occurring after shooting or recording individual program segments.

 

Pre-multiplied alpha

A variation of a bitmap image or alpha blending calculation in which the RGB color values are assumed to be already multiplied by an alpha channel, to reduce computations during Alpha blending; uses the blend operation: d s t = d s t ∗ ( 1 − a l p h a ) + s r c {\displaystyle dst=dst*(1-alpha)+src} capable of mixing alpha blending with additive blending effects

Primitive

A basic unit of geometry for rendering or modelling

Q

R

Ray tracing

Tracing paths of light rays through a 3D scene, may be used for 3D rendering (more commonly for offline rendering), or other tests

RGBA

An RGB color value together with an alpha channel, typically held in bitmap images or intermediates in shading calculations.

RGB image

A bitmap image holding RGB (Red, Green and Blue) color values in 3 image channels.

Render pass

A stage in a rendering pipeline generating some (possibly incomplete) representation of the scene.

Rendering primitive

geometry that can be drawn by a rasterizer or Graphics processing unit, connecting vertices. points, lines, triangles, quadrilaterals

Resource

Data (often held in a buffer managed by a rendering API) read by a graphics pipeline, e.g. texture maps, vertex buffers, shades, index buffers, or other pieces of 3D model data.

S

Screen space

The coordinate space of the resulting 2D image during 3D rendering. The result of 3D projection on geometry in camera space.

Shadow map

A texture buffer holding depth values rendered in a separate render pass from the perspective of a light source, used in Shadow mapping; it is typically rendered onto other geometry in the main rendering pass.

Specular exponent

Controls the glossiness in the phong shading model. Phong shading refers to an interpolation technique for surface shading in 3D computer graphics. It is also called Phong interpolation[1] or normal-vector interpolation shading

T

Terrain rendering

Rendering of landscapes, typically using height maps or voxels. A voxel represents a value on a regular grid in three-dimensional space.

Texture map

A bitmap image/rendering resource used in texture mapping, applied to 3D models and indexed by UV mapping for 3D rendering.

Texture space

The coordinate space of a texture map, usually corresponding to UV coordinates in a 3D model. Used for some rendering algorithms such as texture space diffusion

Triangle primitive

The most common rendering primitive defining triangle meshes, rendered by graphics processing units

U

UV (unwrapping)

The process of flattening a 3D model's surface into a flat 2D plane in a contiguous, spatially coherent manner for texture mapping.

UV (coordinates)

Coordinates in texture space, assigned as vertex attributes and/or calculated in vertex shaders, used for texture lookup, defining the mapping from texture space to a 3D model surface or any rendering primitive.

V

View transformation

A matrix transforming world space coordinates into camera space.

View vector

In shading calculations, a 3D unit vector between the camera and the point of interest on a surface.

W

Wireframe

Refer to (by G4D) as Wireframe models. A wire-frame model is a representation of a 3D or physical object used in 3D computer graphics

Wireframe rendering

A rendering of a 3D model displaying only edge connectivity.

X

Y

Z

 

Z buffer

A 2D array holding depth values in screen space; a component of a framebuffer; used for hidden surface determination.