Time-of-Flight (ToF) and structured light are active depth-sensing methods. Both use projected light and a receiver, but they infer depth differently. The right choice depends on the required range, spatial detail, motion, ambient illumination, target material, size, power, and cost of the complete system.
How the measurements differ
A ToF device estimates distance from the travel time or phase delay of returned light. A structured-light system projects a known pattern and calculates depth from its observed deformation or displacement. The ToF receiver may provide a per-pixel depth map; structured light relies on resolving the projected pattern, its calibration, and its geometry.
Practical comparison
| Question | ToF | Structured light |
|---|---|---|
| What creates depth? | Measured return timing or phase | Observed geometry of a projected pattern |
| What can limit it? | Weak returns, multipath, ambient light, phase ambiguity for some designs | Pattern visibility, occlusion, surface behavior, ambient light |
| Which is better outdoors? | Depends on the exact emitter, optics, receiver, and test conditions | Depends on pattern power, receiver, and test conditions |
| Which is faster or more accurate? | Cannot be decided from the technology name alone | Cannot be decided from the technology name alone |
How to select and test
Define a measurable requirement: for example, valid depth at a stated distance, reflectance, illumination, motion speed, and field of view. Compare candidate systems with the same target set and report error distribution, missing-pixel rate, latency, and power. Security or biometric use also requires separate presentation-attack testing and a complete system assessment; a depth sensor alone does not establish authentication performance.
