Computer Graphics Practice Flashcards

Terminology and concepts covering the rendering pipeline, algorithms, transformations, and display technologies as presented in the lecture notes.

Computer Graphics

The creation, manipulation, and representation of visual images using computers.

Pixel

The smallest unit of a digital image or display, representing a single point of colour.

Raster Graphics

Resolution-dependent images composed of a grid of pixels, commonly found in formats like .bmp, .jpeg, and .png.

Vector Graphics

Resolution-independent images based on mathematical formulas defining lines, curves, and polygons.

Clipping

The process of cutting off or discarding parts of an image that lie outside a defined boundary or viewing region.

Transformation

Operations such as translation, rotation, and scaling that change an object's position, orientation, or size.

Projection

The mapping of $3D$ points to a $2D$ plane, categorized into Orthographic (parallel lines remain parallel) and Perspective (distant objects appear smaller).

Z-buffering

An image-space depth management technique used to determine which objects are in front and should be visible.

Ray Tracing

A technique that simulates light rays interacting with surfaces to produce realistic lighting, shadows, and reflections.

Phong Shading

A shading technique that computes colour and intensity per pixel to provide accurate reflections.

Back-face Culling

The practice of discarding polygons that are not visible to the viewer to improve rendering performance.

Global Illumination

Techniques that simulate how light bounces between surfaces in a scene.

OpenGL

A cross-platform API used for rendering $2D$ and $3D$ vector graphics.

Sutherland's Graphics Workstation

The first graphics workstation, established in $1963$.

SIGGRAPH

The first ACM conference on computer graphics held in $1969$.

Tin Toy

A Pixar production that won an Academy Award in $1989$, marking a milestone in animation history.

Application Stage

The software-based stage of the rendering pipeline that runs on the CPU, reading world-geometry and processing user input.

Geometry Stage

The pipeline stage involving model transformation, shading, viewing transformation, and hidden-surface elimination.

Rasterization Stage

The stage where vertex data is converted into pixel data, including sampling, texture mapping, and colour quantization.

Aliasing

Distortion artefacts, such as jagged edges, that occur when a high-resolution signal is represented at a lower resolution.

Vertex

A single point in $3D$ space.

Mesh

A set of connected polygons that form the surface or structure of a $3D$ object.

Raster Scan

A display method where an electron beam sweeps row by row across the screen to create an image.

Refresh Buffer

Also called a Frame Buffer, this is an interface storing intensity values for every pixel on the screen.

Digital Differential Analyzer (DDA)

A line-drawing algorithm based on the equation $y = mx + b$ that increments one axis and rounds the other to the nearest integer.

Bresenham's Line-Drawing Algorithm

An efficient, incremental, integer-only algorithm used for line drawing that avoids expensive floating-point arithmetic.

Translation

Moving an object by adding an offset to each vertex coordinate: $P_2 = P_1 + T$.

Scaling

Changing an object's size by multiplying vertex coordinates by scaling factors: $x' = x \times s_x$ and $y' = y \times s_y$.

Shear

A transformation that tilts vertical or horizontal lines by changing one coordinate while preserving the other.

Cohen-Sutherland Algorithm

A line-clipping method that divides space into $9$ regions using $4-bit$ outcodes for trivial acceptance or rejection.

Liang-Barsky Algorithm

A parametric line-clipping approach that is significantly more efficient than Cohen-Sutherland for $2D$ and $3D$ lines.

Sutherland-Hodgman Algorithm

A polygon-clipping algorithm that processes one window boundary at a time to generate closed polylines.

Phong Reflection Model

A local illumination model that combines three additive components: ambient, diffuse, and specular reflection.

Lambert's Law

States that reflected energy is proportional to the cosine of the incident angle $\theta$ between the light vector and the surface normal.

Specular Reflection

The component of lighting that models bright highlights on shiny surfaces, depending on the viewer's position.

Mach Bands

An optical illusion that exaggerates contrast at edges between differently shaded facets, commonly seen in flat shading.

Gouraud Shading

A colour-interpolation technique where the lighting equation is evaluated at vertices and then bilinearly interpolated across the polygon.

Scan-Line Method

A visible surface detection method that processes depth information for only one scan-line at a time using edge and polygon tables.

BSP Tree

Binary Space Partitioning tree; an object-space method used for static scenes to determine correct visibility through plane splitting.

SSAA (Supersampling)

A spatial anti-aliasing technique that renders an image at a higher resolution and then downsamples it.

TAA (Temporal Anti-Aliasing)

A post-processing anti-aliasing method that uses information from previous frames to smooth edges and reduce flicker.

Radiosity

A rendering technique that simulates diffuse light distribution and indirect light bouncing, often used in architectural visualization.