ADAS in cars explained: Why it uses four cameras and a radar system
Last Updated: 2026-07-26 22:42:53
Advanced driver assistance systems, or ADAS, use cameras, radar and other sensors to monitor the road and warn drivers about potential hazards. Depending on the vehicle, the system may also control steering or braking briefly to reduce the risk of a collision.
Some cars advertise four-camera ADAS systems supported by radar. However, four cameras are not a universal requirement. The number of sensors depends on the features offered, vehicle design and level of driver assistance.
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What the Four Cameras Monitor
A four-camera arrangement generally includes one camera at the front, one at the rear and one on each side of the vehicle. Their combined view helps the system observe areas that a single front-facing camera cannot cover.
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The front camera can identify lane markings, traffic signs, vehicles and pedestrians. Side cameras help monitor adjoining lanes and blind spots, while the rear camera supports reversing, parking and rear cross-traffic warnings.
Some cars use these cameras to create a stitched 360-degree view around the vehicle. Others use separate surround-view cameras for parking and a dedicated windscreen-mounted camera for ADAS functions. Buyers should therefore check which cameras actually support safety features.
Why Radar Is Also Required
Cameras are effective at recognising shapes, lane markings, colours and signs, but judging distance and relative speed from images alone can be difficult.
Radar uses radio waves to measure how far away an object is and how quickly it is approaching or moving away. It supports functions such as adaptive cruise control, forward-collision warning and automatic emergency braking.
Radar can also work more consistently than a camera in darkness, rain or fog. However, it cannot identify visual details as accurately as a camera. This is why many ADAS systems combine information from both sensors.
How Sensor Fusion Improves Accuracy
The vehicle’s computer compares camera and radar readings through a process called sensor fusion. A camera may recognise an object as a car, while radar confirms its distance and speed.
Using two sources can reduce false warnings and help the system decide whether it should alert the driver, adjust speed or apply the brakes. Ultrasonic sensors may also be included for detecting nearby objects while parking.
ADAS Still Requires an Attentive Driver
ADAS is not the same as autonomous driving. Its performance can be affected by faded lane markings, construction zones, heavy rain, glare, dirt or damage covering the sensors—conditions frequently encountered on Indian roads.
Cameras and radar may also require recalibration after a windscreen replacement, collision or repair. Drivers should keep the sensor areas clean, follow the manufacturer’s maintenance instructions and remain ready to take control.