Ask An Engineer | Machine Vision System for Inspecting 3D Objects

by | EPIC Machine Vision

Question: I am interested in a system that inspects parts on a production line in our manufacturing plant. What type of machine vision system would be needed for inspecting 3D objects?

Answer: When it comes to inspecting 3D objects, one option for inspection is a stereoscopic machine vision system. A stereoscopic vision system uses stereo vision to extract 3D information from multiple 2D views of a scene.

For Stereo Vision, two cameras are set up to view one object to accurately see it as a 3D image. The same principle for depth perception of human eyes is at work in stereo vision.


The stereo vision system must be calibrated. This is an important step to achieve accuracy in 3D reconstruction. 3D charts and/or software can be used to perform this task.

Once the cameras are calibrated, the same points in one image are set to match up with the same points in the other. This is called rectification. Rectification is an important step for computing disparity. It is used to simplify the problem of finding matching points between the two images. Calibration and image rectification is further simplified and process times are increased by epipolar geometry.

By comparing the two images, relative depth information can be computed and represented in the form of a disparity map. You can use the disparity map to reconstruct the 3D scene by projecting the 2D contents of a scene to three dimensions.

For more information and details on a stereo machine vision system, read Chris Walker’s blog post on Stereo Vision Basics…

About EPIC Machine Vision

EPIC provides complete design and fabrication of turnkey vision systems. Services include: lighting design, electrical design, 3D modeling of mechanical designs and custom mounting systems, programming inspection algorithms along with integration to PLCs or other automated equipment, system documentation, and training.  EPIC engineers deliver a true, customized, turnkey vision solution.

Find a machine vision solution that is right for your company. Click here to contact Dan Nadolny, EPIC’s Vision Group Coordinator…


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