Overview
Normal mapping reads a normal vector from a texture, transforms it from tangent space to the surface's shading space, and uses it for lighting calculations.
CoreSource checked
Normal Mapping
Adds lighting detail by perturbing shading normals from a texture instead of changing geometry.
Quick Facts
Compact metadata for implementation and discovery.
- Category
- Rendering
- Difficulty
- Intermediate
- Family
- Surface Shading
- Tier
- Core
- Status
- Verified
- Review
- Source Checked
- Sources
- 1
- Formulas
- 1
- Relationships
- 3
- Code example
- Ready
- Visualization
- Ready
Core Concepts
tangent spacenormal perturbationtexture lookupsurface lighting
Quick facts
Complexity
Runtime and memory behavior at a glance.
Best
O(1)
Average
O(pixels)
Worst
O(pixels)
Space
O(texture size)
When to Use
- Use when fine surface detail should affect lighting without adding mesh triangles.
- Use when tangent, bitangent, and normal data can be generated consistently.
When Not to Use
- Avoid when the silhouette must change; normal maps do not alter geometry.
- Avoid when tangent-space conventions differ between asset baking and rendering.
What It Does
- Perturbs surface normals from a texture to add lighting detail without extra geometry
- Uses tangent space and normal perturbation to guide the work.
- Produces rendered image.
Use Cases
- Real-time graphics
- Offline rendering
- Lighting and visibility effects
Inputs
- Scene geometry
- Materials
- Camera and lighting state
Outputs
- Rendered image
- Visibility or shading buffers
Key Formulas (1)
Normal transform
nworld = normalize(TBN · ntangent)
n_world = normalize(TBN * n_tangent)Moves a sampled tangent-space normal into world or view space.
Pseudocode
- 1.Sample the normal-map texel
- 2.Decode it into a tangent-space normal
- 3.Build or read the tangent-to-world basis
- 4.Transform and normalize the normal
- 5.Use the transformed normal in the lighting equation
Canonical Example
- Input
- flat quad with a brick normal map and one light
- Output
- brick grooves appear in lighting while the quad silhouette remains flat
- Explanation
- The normal texture changes the lighting direction at each fragment, not the mesh shape.
Implementation Notes
- Decode texture values from [0, 1] to [-1, 1].
- Transform the decoded normal with a consistent tangent basis.
- Renormalize the shading normal before evaluating lighting.
Common Pitfalls
- Green-channel orientation and tangent handedness mismatches can invert detail.
- Normal maps should not be sampled as gamma-corrected color data.
- Missing or inconsistent tangents create seams and lighting artifacts.
Interactive Mechanism Walkthrough
Spatial Primitive & Sweep-Line CanvasShow rays, samples, buffers, or shading terms that contribute to the final pixel.
Step 1 of 5: Sample the normal-map texel
rendering-mechanismNotes
Normal mapping affects shading only; displacement or tessellation is needed for actual geometric relief.
Sources (1)
What each reference supports for this entry.
Cohen, Olano, and Manocha 1998
PaperAppearance-preserving simplification paper using normal maps to preserve surface detail.
Open sourceExplore Next
Good next jumps from the relationship graph, ranked for useful discovery.
Relationships
View full relationship pageConceptual neighborParallax Occlusion Mapping
Both add apparent surface detail without changing base geometry.
Often paired withPhong Shading
Normal maps modify shading normals used by local lighting models.
Related Algorithms
Tags
GraphicsShadingTexture MappingLighting