Pseudo3D

Pseudo-3D is a class of rendering and presentation techniques that simulate three-dimensional depth on a two-dimensional display without fully rendering a volumetric 3D scene. The term covers methods that rely on perspective cues, relative sizing, shading, and motion parallax to convey depth while keeping geometry and shading simpler than real 3D.

Common approaches include 2.5D rendering, such as ray casting, in which a two-dimensional map is used to compute visible walls and project them into vertical columns to produce the illusion of space. Parallax scrolling aligns background layers at different speeds to suggest distance. Sprite-based rendering uses scaling and billboarding to depict objects at several depths. Isometric or oblique projections render a pseudo-3D grid where depth is inferred from the angle and scale of objects.

Historically, pseudo-3D enabled games to achieve immersive visuals on modest hardware. Wolfenstein 3D (1992) popularized the 2.5D ray-casting approach to produce a 3D-like corridor world. Doom (1993) extended the technique with more complex scenes and lighting, but it remains classified as pseudo-3D rather than true three-dimensional rendering. As hardware advanced, true 3D rendering supplanted many pseudo-3D techniques, though the latter still influence certain engines and visual styles.

In other media and software, pseudo-3D appears in user interface effects that simulate depth, such as beveled buttons, perspective-dependent icons, or 2D diagrams with depth cues. It also appears in isometric strategy games and retro-style art that evoke early 3D aesthetics without full 3D pipelines.