Editor's Note: This is Part 2 of a two-part series on 3D machine vision. Part 1 can be found here.
Manufacturers attain 3D results with various systems, including stereo cameras and "time-of-flight" techniques (which resolve distances based on the speed of light). The most common of these systems is vision triangulation, which uses multiple images from the cameras to determine the object's position in space and its 3D coordinates.
"Triangulation systems are typically built on top of the same cameras that you'd use in 2D applications," says John Petry, vision software marketing manager for Cognex Corp. "But it involves a second step where you take the results from the cameras and combine them to determine your 3D pose."
Increasingly, manufacturers are using such methods for applications that previously used visual inspection and mechanical methods. Aicon 3D developed a tube measurement system that calculates a pipe's geometry. The system employs multiple cameras from Allied Vision Technologies to create parallel images for inspecting irregularly shaped pipes. The system has been used to analyze long and winding fuel and brake lines in automotive assemblies.
Smaller cameras are a key element in such systems, largely because cameras must often be mounted atop mobile robot heads. Vision Components GmbH's VC nano 3D measures just 140mm x 70mm x 35mm -- less than half the size of analog cameras of a generation ago. Increasingly, such cameras are also offering simplicity. The VC nano 3D integrates the camera and laser in a single pre-calibrated unit.
"Not long ago, if you wanted laser triangulation, you had to buy the camera and the laser separately," said Endre Toth, director of business development for Vision Components. "Then you had to have the knowledge to put the two together and calibrate the system yourself."
Lower-cost cameras are also appealing to manufacturers. MVTec has teamed with Microsoft to employ the Kinect camera with its Halcon software. Kinect, originally developed for the Microsoft Xbox 360, is expected to bring a lower-cost option to the machine vision market. Similarly, the VC nano 3D has cut costs by employing widely used CMOS, instead of CCD (charge-coupled device) technology.