Applications that benefit from 3-D sensing
3-D sensing is helping machine vision solving many automation challenges, but it's not suited for all applications. Knowing what types of 3-D vision are out there and understanding the application helps.
Machine vision is a major enabler of industrial automation technology. Traditionally, 2-D imaging has been the primary machine vision technology in the industrial sector. Today, however, 3-D sensing is solving some of the most difficult automation challenges and bringing a whole new level of capabilities to industrial automation. 3-D sensing can be a powerful automation solution, but it’s not suited for all applications. Some processes will benefit from 2-D vision instead.
Operating 3-D sensing parameters
To determine whether 3-D sensing is beneficial for a particular application, it’s best to first take a look at the general operating parameters of 3-D sensing and compare this with your own application. One major limitation in 3D imaging applications is depth of field, or extending the Z-axis.
Depending on the type of 3-D imaging technology being used, depth of field can range anywhere from below 50 mm to 100 m. Different technologies have different operating ranges, but what they all have in common is that increasing the depth of field requires a shrinking of the aperture. This reduces the amount of light captured, which can lower image quality.
Types of 3-D sensing systems
Depth of field is a critical consideration, but so is the type of 3-D imaging technology. There are several different types of 3-D sensing systems out there including:
Laser triangulation: One of the most common types of 3-D sensing, laser triangulation works by projecting a laser onto a part or other surface. Depth is measured by the deformation of the laser, making this technology good for large depth of field applications.
Photogrammetry: A method of computing a 3-D reconstruction based on a large number of 2-D images of an object. Photogrammetry is a common alternative to LIDAR systems.
Stereo vision: This type of 3-D imaging mimics the way humans perceive 3-D images—two sensors are used at different angles to calculate and represent depth. Typically stereo vision is used for applications that don’t require measurements, such as counting people.
Structured light: With no need for moving parts, structured light 3D sensing systems are some of the most sophisticated solutions out there. They leverage an innovative projection technique to encode 3-D information directly on the scene.
Time-of-flight: These systems detect the time of light travel between the light emitter, an inspected object, and back to the detector. Time-of-flight systems are either area sensing or LIDAR systems.
Deciding whether or not a 3-D sensing system is right for an application is difficult. There are a number of 3-D technologies, produced by an ever-expanding range of suppliers, all with different operational parameters and benefits. To start making this decision, it’s best to look at the requirements of your application and how these align with the technologies available.
This article originally appeared on the AIA website. The AIA is a part of the Association for Advancing Automation (A3). A3 is a CFE Media content partner. Edited by Chris Vavra, production editor, Control Engineering, firstname.lastname@example.org.
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Original content can be found at www.visiononline.org.
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