Displacement Mapping: The 3D Graphics Technique That Actually Moves Geometry

Displacement mapping is a 3D graphics technique that physically moves (displaces) mesh vertices along their normals based on values in a grayscale texture map. Unlike bump mapping or normal mapping — which only simulate surface detail by altering how light interacts with a flat surface — displacement mapping actually changes the geometry, producing correct silhouettes, self-shadowing, and parallax. ## How It Works A displacement map is a grayscale image where brightness values represent height. White pixels push vertices outward along their normals; black pixels pull them inward; grey is neutral. The mesh must be sufficiently tessellated (subdivided) for the displaced geometry to capture the map's detail — either pre-subdivided or dynamically tessellated using hardware tessellation shaders. ## Applications - **Film VFX**: Detailed terrain, creature skin, architectural detail at render time - **Game engines**: Hardware tessellation enables real-time displacement for terrain and surfaces - **Bump Mesh: Free Browser-Based Displacement Texturing for 3D Prints**: Surface topology must be physically accurate, not just visually simulated — displacement mapping is the appropriate technique because the printed object needs real geometry ## Tradeoffs Displacement mapping is more computationally expensive and requires higher mesh density than normal maps. For distant objects or flat surfaces, normal maps remain more efficient. The typical approach in modern rendering is to use displacement for close-up hero surfaces and normal maps for everything else.