LiDAR vs Radar vs Camera: Which Sensor Does a Robot Need?
Three common robot sensors compared in plain language: what each sees well, where each fails, and why many robots use more than one.
Short answer: a camera is cheap and tells you what something is, a lidar tells you precisely where things are in 3D, and radar works in rain, fog and dark and measures speed directly. Most serious robots combine them, which is called sensor fusion.
At a glance
| Camera | Lidar | Radar | |
|---|---|---|---|
| Measures | Light (colour images) | Laser pulse timing (distance) | Radio wave echoes (distance and speed) |
| Strength | Recognises objects, signs, people; low cost | Accurate shape and distance | Works in bad weather; measures speed |
| Weakness | Poor in dark or glare; no direct distance | Costs more; can struggle with rain, fog and glass | Coarse detail |
| Typical use | Object detection, lane finding | Mapping, obstacle avoidance | Collision warning, long range detection |
Read more: camera vision, lidar, radar.
Which one to choose
- Learning or a hobby robot: start with a camera and a cheap distance sensor.
- Indoor mapping robot: a 2D lidar is the classic choice and pairs with SLAM.
- Outdoor robot or vehicle: add radar because it keeps working when cameras and lidar are degraded.
Why not just one?
Each sensor has blind spots in different conditions. A camera can be blinded by sun glare, and radar cannot read a road sign. Fusing them lets the strengths cover the weaknesses. Some companies deliberately use fewer sensor types to cut cost, and the right mix depends on the job and budget.
FAQ
Which is cheapest? Cameras, by a wide margin.
Can a camera measure distance? Yes, using two cameras (stereo) or software estimates, but it is less direct than lidar or radar.
What is the best sensor for a beginner robot? A camera plus an ultrasonic or infrared distance sensor.
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