What Computer Graphics Is

Computer Graphics (CG) is the synthesis and manipulation of visual content using a computer. Unlike image processing, which starts from an image, CG starts from a model (geometry, lights, materials) and produces an image.

Major Applications

• GUIs and window systems (every modern OS).
• CAD/CAM - mechanical, electrical, architectural design.
• Entertainment - games, films, VFX.
• Scientific visualization - molecular, climate, fluid simulations.
• Medical imaging - CT, MRI volume rendering.
• Cartography and GIS.
• Virtual and Augmented Reality.
• Simulation and training (flight sims, surgical sims).

Non-Interactive vs Interactive Graphics

• Non-Interactive (Passive): User cannot influence the image while it is being produced. Examples: a printed chart, a pre-rendered animated film. The image is computed once and consumed.
• Interactive: User can change parameters in real time and see results immediately. Examples: 3D modelers, games, dashboards. Requires fast feedback (typically 30-120 fps).

Conceptual Framework for Interactive Graphics

Five components form the classical Foley-Van Dam loop:

1. Application Model - data describing the world (vertices, materials, scene graph).
2. Application Program - the user-written code that manipulates the model.
3. Graphics System - the API and pipeline (OpenGL, DirectX, Vulkan, software).
4. Display Device - monitor, projector, HMD.
5. Input Devices - keyboard, mouse, stylus, controllers, cameras.

Comparison Table

A Note on the Pipeline

The interactive pipeline today (Application -> Geometry -> Rasterization -> Fragment -> Framebuffer -> Display) is the descendant of the framework above; later units expand each stage.