CGI — primary senses: Computer-Generated Imagery, Common Gateway Interface, and others

Computer-Generated Imagery (visual media)

Computer-Generated Imagery covers a range of techniques used in film, television, advertising, architecture, scientific visualization and games. Typical steps include modeling (creating 3D geometry), texturing, lighting and rendering. Techniques used in modern pipelines include polygonal modeling, procedural generation, particle and fluid simulation, motion capture for realistic movement, ray tracing or path tracing for physically based lighting, and compositing to integrate rendered elements with live-action footage. Common software and tools are specialist 3D and compositing packages used by artists and studios. CGI can range from stylized art to photorealistic effects; achieving realism involves careful attention to lighting, materials, motion blur and integration with real-world camera characteristics.

Common Gateway Interface (web)

The Common Gateway Interface is a simple protocol that lets a web server run an external program to produce an HTTP response. A CGI program receives request metadata via environment variables and any message body on standard input, performs processing, and writes headers and content to standard output. Because each request typically spawns a separate process, plain CGI can be inefficient under high load. Over time it has been largely supplanted by persistent application servers, server modules and interfaces such as FastCGI, WSGI/ASGI, servlet containers and native web frameworks that offer better performance and resource management. Security considerations for CGI programs include careful input validation and output encoding.

Other meanings and disambiguation

• CGI Inc. — a large Canadian-based information technology and consulting company commonly called CGI.
• Clinical Global Impression (CGI) — a brief clinician-rated scale frequently used in psychiatry to record illness severity and change.

When encountering "CGI," use surrounding terms to disambiguate: references to films, rendering or effects point to Computer-Generated Imagery; server scripts, environment variables or HTTP indicate the Common Gateway Interface; corporate or clinical contexts suggest the company or the rating scale.