High-speed Real-time 3D Imaging Using Fringe Projection
Fringe projection profilometry (FPP) is a noncontact, optical, active, triangulation-based 3D reconstruction technique that is well known for its simple implementation, low cost, and high accuracy. FPP works on the same principle as stereo vision, where an object's coordinate in 3D space is derived by triangulating between pixels of two cameras. SLI avoids the computational complexities of matching pixels across camera views by replacing one of the two component cameras with a projector that generates a series of fringe patterns. By analyzing the change in the pattern at a particular point on the target object's surface (a process known as phase demodulation and unwrapping of the captured fringes), unique correspondences can be derived between the camera and projector pixels.
However, traditional fringe projection profilometers are usually designed to measure static object shapes under non-time-critical measurement conditions, their measurement of moving objects is limited. Besides, it is difficult to retrieve the absolute phase for spatially isolated surfaces simultaneously and rapidly since in the phase unwrapping, fringe orders will be ambiguous, making the depth difference between spatially isolated surfaces indiscernible. However, many areas of science and industry require 3D measurements made in high-speed or even real-time. One example is a human-to-computer interface where hand gestures are used to control a computer.
