Phase shifting algorithms for fringe projection profilometry: A review

Fourier transform profilometry:: a review

Dynamic 3-D shape measurement method: A review

A novel dual-frequency pattern is developed which combines a high-frequency sinusoid component with a unit-frequency sinusoid component, where the high-frequency component is used to generate robust phase information, and the unit-frequency component is used to reduce phase unwrapping ambiguities. With our proposed pattern scheme, phase unwrapping can overcome the major shortcomings of conventional spatial phase unwrapping: phase jumping and discontinuities. Compared with conventional temporal phase unwrapped approaches, the proposed pattern scheme can achieve higher quality phase data using a less number of patterns. To process data in real time, we also propose and develop look-up table based fast and accurate algorithms for phase generation and 3-D reconstruction. Those fast algorithms can be applied to our pattern scheme as well as traditional phase measuring profilometry. For a 640 x 480 video stream, we can generate phase data at 1063.8 frames per second and full 3-D coordinate point clouds at 8.3 frames per second. These achievements are 25 and 10 times faster than previously reported studies.

Dual-frequency pattern scheme for high-speed 3-D shape measurement.

Absolute phase retrieval methods for digital fringe projection profilometry: A review

We present a method that uses two groups of fringe patterns on one grating for phase-measuring profilometry. A two-frequency grating is projected onto the object. The high frequency is N (N = 3, 4, 5, :...) times greater than the low frequency. Using a proper phase shift, we calculated the wrapped phases of the two frequencies. When the linearity of the two phases are considered, an accurate phase of the high frequency can be unwrapped. Because the low frequency is N times more insensitive to height discontinuity, the system is more tolerable to height discontinuity.

Two-frequency grating used in phase-measuring profilometry

An improved phase algorithm for phase-measuring profilom- etry (PMP) is presented. In comparison with the traditional algorithms, it can remove the influence of the carrier frequency before unwrapping and slow down the variation of the phase. This new algorithm makes the procedure of phase unwrapping easier and more automatic. It is espe- cially suitable for PMP with a high-frequency grating. © 1997 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(97)01406-2)

Hong-Jun Su

Papers

Two-frequency grating used in phase-measuring profilometry

Phase algorithm without the influence of carrier frequency