Improve Temporal Fourier Transform Profilometry for Complex Dynamic Three-Dimensional Shape Measurement

Abstract

The high-speed three-dimensional (3-D) shape measurement technique has become more and more popular recently, because of the strong demand for dynamic scene measurement. The single-shot nature of Fourier Transform Profilometry (FTP) makes it highly suitable for the 3-D shape measurement of dynamic scenes. However, due to the band-pass filter, FTP method has limitations for measuring objects with sharp edges, abrupt change or non-uniform reflectivity. In this paper, an improved Temporal Fourier Transform Profilometry (TFTP) algorithm combined with the 3-D phase unwrapping algorithm based on a reference plane is presented, and the measurement of one deformed fringe pattern producing a new 3-D shape of an isolated abrupt objects has been achieved. Improved TFTP method avoids band-pass filter in spatial domain and unwraps 3-D phase distribution along the temporal axis based on the reference plane. The high-frequency information of the measured object can be well preserved, and each pixel is processed separately. Experiments verify that our method can be well applied to a dynamic 3-D shape measurement with isolated, sharp edges or abrupt change. A high-speed and low-cost structured light pattern sequence projection has also been presented, it is capable of projection frequencies in the kHz level. Using the proposed 3-D shape measurement algorithm with the self-made mechanical projector, we demonstrated dynamic 3-D reconstruction with a rate of 297 Hz, which is mainly limited by the speed of the camera.

High-speed three-dimensional shape measurement with inner shifting-phase fringe projection profilometry

“…Equations ( 8) and ( 9) are the key steps to get Eq. (7). Since the wrapped phase is a curve with T periods, we use the single-frequency shifting phase to get the fringe order k for each cycle of the wrapped phase:…”

“…FTP uses only a single pattern for 3D shape measurement to promise the high speed. However, it suffers an overlapping spectrum, which limits its performance and makes it hard to calculate complex objects with large curved surfaces [7][8][9] . Compared with FTP, PSP is popular among researchers because of its high stability and high efficiency [9][10][11] .…”

Investigation of an Inline Inspection Method for the Examination of Cylinder-like Specular Surfaces Using Deflectometry

“…However, these approaches are difficult to transfer to the use of a line scan camera for cylindrical surfaces imaging. Other approaches such as [24,25] use Fourier transform profilometry (FTP) to extract surface information. Again, a fringe pattern is used, but this time it is projected onto the surface.…”

Vibration measurement by projection of phase-modulated and amplitude-modulated structured light

“…The images of projected fringe patterns acquired by high-speed cameras have also been used for temporal vibration analyses: in (Fu, 2010), the vibration of low-frequency vibrating object was studied by projecting a sequence of fringe patterns produced by a moving grating and captured by a high-speed camera; Talbot fringes generated by a Ronchi grating were projected and analyzed by Fourier Transform to obtain the whole-field time-resolved vibration map on an Aluminum cantilever (Rodriguez-Vera et al, 2009). Temporal Fourier transform profilometry (TFTP) (Zhang et al, 2019;Zhang et al, 2020) combined with a mechanical light chopper was used for dynamic profilometry.…”