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MACHINE VISION · STEREO CAMERAS

What Is a Stereo Camera?

A stereo camera is a camera with two image sensors set a fixed distance apart, like a pair of eyes. By finding the same point in both images and measuring how far it shifts between them, it calculates the distance to every pixel, so one sensor gives a robot or vehicle a 3D depth map as well as a color image.

01

The Short Answer

A stereo camera captures two images of the same scene at the same moment, from two sensors mounted side by side. Software matches each point in the left image to the same point in the right image and turns the difference into distance, so the camera outputs depth for the whole scene, not just a flat picture.

That is why stereo vision cameras are a common choice for robots, autonomous vehicles and mapping systems that need to judge how far away things are while they move.

02

How a Stereo Camera Measures Depth

The distance between the two sensors is called the baseline. A nearby object appears in quite different positions in the two images, while a distant object barely moves; that shift is the disparity, and the camera triangulates depth from it. A longer baseline resolves depth further away, and a shorter baseline works closer in.

The Stereolabs range shows the trade-off clearly. The ZED X has a 120 mm baseline and measures out to 35 m with its narrow lenses, while the ZED X Nano uses an 18 mm baseline to measure from 3 cm to 2 m on a robot wrist. Modern stereo cameras also use neural networks to fill in surfaces with little texture, where simple pixel matching struggles.

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    Stereo cameras Passive depth from two sensors, working in daylight and indoors, with color and depth from one device.
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    Active infrared depth cameras Project a pattern to help indoors at short range, but sunlight can wash the pattern out.
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    Lidar Measures distance directly with laser pulses at long range, without the color image a camera provides.
03

How We Apply It

We pair depth cameras with NVIDIA Jetson computers for mobile robots, robot arms, agricultural machines and outdoor inspection, choosing the baseline, lens and interface to suit the distances the machine has to measure. For machines in the field we usually specify GMSL2 stereo cameras, which carry video and power over one locking coax cable.

Our guide to setting up a ZED X robotics stack with ROS 2 covers the software side, from the camera driver to the depth and point cloud topics your robot reads.