CGI (Computer Generated Imagery)

CGI (Computer-Generated Imagery) is the broad term for any visual content created entirely or substantially within a computer rather than captured by camera — distinct from VFX which broadly covers all visual enhancement work (including non-CG operations like rotoscoping and compositing live elements). CGI workflows include: modeling (creating 3D geometry in Maya, Blender, Houdini, ZBrush), texturing (painting surface details in Substance Painter, Mari), rigging (setting up skeletal systems for animation), animation (keyframed or motion-captured movement), lighting (matching the live plate's illumination using HDR reference probes and matched light positions), simulation (cloth, fluids, particles, destruction, dynamics), and rendering (computing the final pixels with ray tracing in Arnold, RenderMan, Redshift, Karma, Cycles, or rasterization in real-time engines). Photorealistic CG requires meticulous attention to physical accuracy: subsurface scattering on skin and translucent materials, dispersion and chromatic aberration in lenses, motion blur matching the camera's shutter angle, depth-of-field matching the lens aperture, and grain matching the sensor. Feature film CG sequences (a CGI creature, an entire environment) can require months of work per shot and budgets in the hundreds of thousands. The industry's flagship demonstrations: ILM, Weta FX, MPC, Framestore, DNEG. The line between 'CGI' and 'live action with VFX' has blurred substantially since the 2010s. Reference: Birn's 'Digital Lighting & Rendering' remains a foundational text.