Overview
Ray Tracing follows rays to find visible surfaces and can spawn more rays for shadows, reflection, and refraction.
FoundationSource checked
Ray Tracing
Renders images by tracing rays from the camera into a scene.
Quick Facts
Compact metadata for implementation and discovery.
- Category
- Rendering
- Difficulty
- Advanced
- Family
- Ray-Based Rendering
- Tier
- Foundation
- Status
- Verified
- Review
- Source Checked
- Sources
- 1
- Formulas
- 1
- Relationships
- 20
- Code example
- Not ready
- Visualization
- Ready
- Aliases
- Raytracing
Core Concepts
camera rayray-surface intersectionrecursive visibilitylighting samplerendered imagegeometric calculationvisibility orderingrecursive decomposition
Quick facts
Complexity
Runtime and memory behavior at a glance.
Best
O(p log n)
Average
O(p r log n)
Worst
O(p r n)
Space
O(n)
When to Use
- Use it when visibility is naturally expressed as ray-surface intersection.
- Use it for reflections, refractions, shadows, and high-quality offline rendering.
- Use acceleration structures for nontrivial scenes.
When Not to Use
- Avoid brute-force ray tracing without acceleration structures on large scenes.
- Avoid deep recursive ray paths without a depth or contribution limit.
- Avoid it when rasterization gives the needed quality within a tighter frame budget.
What It Does
- Finds ray-surface intersections
- Computes lighting along rays
Use Cases
- Photorealistic rendering
- Reflection and shadow simulation
- Offline image generation
Inputs
- Scene geometry
- Materials
- Camera
- Lights
Outputs
- Rendered image
Key Formulas (1)
Ray equation
point(t) = origin + t · direction
point(t) = origin + t * directionDefines points along a ray for intersection tests.
Pseudocode
- 1.Create one or more rays for each pixel
- 2.Find the nearest surface hit for each ray
- 3.Shade the hit using lights and material properties
- 4.Trace secondary rays when needed
- 5.Average samples into the final pixel color
Canonical Example
- Input
- one sphere, one camera ray through the center pixel
- Output
- nearest hit point on the sphere
- Explanation
- The ray is intersected with the sphere, and the closest positive hit determines the visible surface.
Implementation Notes
- Generate primary rays from camera parameters and pixel sample positions.
- Find the closest positive intersection along each ray.
- Use BVHs or other acceleration structures before scaling beyond tiny scenes.
Common Pitfalls
- Testing every ray against every object instead of using an acceleration structure.
- Choosing epsilon offsets that cause either self-intersection or light leaks.
- Letting recursive reflection or refraction paths run without a termination rule.
Interactive Mechanism Walkthrough
Spatial Primitive & Sweep-Line CanvasShow rays leaving the camera and hitting scene objects.
Step 1 of 5: Create one or more rays for each pixel
camera-raysNotes
Ray tracing becomes practical for complex scenes only with spatial acceleration and careful sampling.
Sources (1)
What each reference supports for this entry.
Physically Based Rendering
BookRendering reference covering ray tracing, visibility, materials, and sampling.
Open sourceExplore Next
Good next jumps from the relationship graph, ranked for useful discovery.
AlternativesRasterization
Rendering · Foundation
Rasterization and ray tracing are different rendering pipelines.
Compare with thisAlternativesRay Marching
Rendering · Extended
Ray marching samples along rays rather than solving explicit intersections.
Compare with thisUsesBVH Traversal
Rendering · Core
Ray tracing commonly uses BVH traversal to accelerate ray-scene intersection.
Compare with thisUsesRay-Triangle Intersection
Geometry · Extended
Ray tracers use ray-triangle tests at primitive intersections.
Compare with thisRelationships
View full relationship pageUsesBVH Traversal
Ray tracing commonly uses BVH traversal to accelerate ray-scene intersection.
Prerequisite ofPath Tracing
Path tracing builds on ray tracing with stochastic light transport sampling.
GeneralizesWhitted Ray Tracing
Whitted ray tracing is a recursive ray tracing model for reflections and refractions.
Related Algorithms
Tags
GraphicsGeometryVisibilityRecursion