Dynamic microscopic 3D shape measurement based on marker-embedded Fourier transform profilometry

Abstract

In recent years, the fringe projection profilometry (FPP) technique has shown great prospects in the field of dynamic 3D measurement of microscopic surface shape. However, under dynamic conditions, it is desirable to use fewer projected patterns to minimize the sensitivity to motion. The commonly used phase-shifting method needs at least three fringe patterns to retrieve the wrapped phase, which depends heavily on the high-speed hardware to alleviate the effect of motion. Besides, to achieve an unambiguous measurement, at least two wrapped phase maps are required to obtain the absolute phase map, resulting in six pattern projections. In this paper, we propose the marker-embedded Fourier transform profilometry (MEFTP), which extends the modified Fourier transform profilometry with two embedded markers suited to assist the phase-unwrapping process. Combining the embedded markers with temporal phase difference information, the absolute phase can be reliably reconstructed with only two projected patterns. Furthermore, since the phase information is only encoded within a single high-frequency fringe, MEFTP is more suitable for measuring fast-moving or surface-changing objects compared with the phase-shifting method. Experiments on both static and dynamic scenes are performed, verifying that our method can achieve an accurate and robust measurement of a vibrating diaphragm at the speed of 200 frames per second.

3D Measurement of Human Chest and Abdomen Surface Based on 3D Fourier Transform and Time Phase Unwrapping

“…To avoid the appearance of ∆N MAX , assume that the remainder measurement error satisfies Condition A, |∆r r /P| < 0.25, ∆r g /P < 0.25, |∆r b /P| < 0.25 (16) The measured valuesr r ,r g , andr b of the remainders r r , r g , and r b can be expressed as: where { } is a fractional operation. Then, if the difference between the fractional part of the remainder measurement satisfies Condition B, then:…”

“…After this process, useful signals and interference can be separated better. This method becomes an effective measurement for 3D measurement of flat surfaces [16]. In this paper, the image sequences of the chest and abdomen surface are taken as a 3D one, which is analyzed by 3D Fourier transformation.…”

A fringe projection profilometry scheme based on embedded speckle patterns and robust principal component analysis

“…Budianto et al [9] embed several strip markers within a single fringe pattern to facilitate phase unwrapping and retrieve the marker cue through the dual-tree complex wavelet transform. Similarly, Hu et al [10] propose a two-marker approach by embedding two specially designed markers with opposite intensity, which can enhance the absolute phase retrieval. However, these methods can only be used for reconstructing simple objects and may perform poorly for complex scenes.…”

High-speed three-dimensional shape measurement using phase measurement profilometry without phase unwrapping

“…[7][8][9] In general, it is significant to use fewer fringe patterns to get the results in a high-speed measurement. 10 Because oneshot technologies only need one frame to get the wrapped phase, they have the potential to be used in high-speed measurement. It mainly contains color coding, 11 FTP, 12 and composite pattern; 13 however, these methods still have shortcomings.…”