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

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1808
Author(s):  
Yihang Liu ◽  
Qican Zhang ◽  
Haihua Zhang ◽  
Zhoujie Wu ◽  
Wenjing Chen
Keyword(s):  
Fourier Transform ◽  
High Speed ◽  
Three Dimensional ◽  
Reference Plane ◽  
Shape Measurement ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Fourier Transform Profilometry ◽  
Sharp Edges ◽  
Band Pass

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.

3D Profile Variety Measurement of Pectoral Fin in Fish Fast Start

2011 ◽  
Vol 83 ◽  
pp. 280-284
Author(s):  
Ming Jiang ◽  
Shu Zhang ◽  
Xiao Yuan He
Keyword(s):  
Fourier Transform ◽  
High Speed ◽  
Kinetic Characteristic ◽  
Three Dimensional ◽  
Pectoral Fin ◽  
Fourier Transform Profilometry ◽  
Fast Start ◽  
Fringe Patterns ◽  
3D Information ◽  
3D Profile

Fast-starts are brief, sudden accelerations used by fish during predator-prey encounters. In this paper, a three-dimensional (3D) test and analysis method is critical to understand the function of the pectoral fin during maneuvers. An experiment method based on Fourier Transform Profilometry for 3D pectoral fin profile variety during fish maneuvers is proposed. This method was used in a carp fast-start during prey. Projecting the moiré fringes onto a carp pectoral fin it will produce the deformed fringe patterns contain 3D information. A high speed camera captures these time-sequence images. By Fourier transform, filter, inverse Fourier transform and unwrap these phase maps in 3D phase space, the complex pectoral fin profile variety were really reconstructed. The present study provides a new method to quantify the analysis of kinetic characteristic of the pectoral fin during maneuvers.

scholarly journals High Speed 3D Shape Measurement with Temporal Fourier Transform Profilometry

2019 ◽  
Vol 9 (19) ◽  
pp. 4123 ◽  
Author(s):  
Haihua Zhang ◽  
Qican Zhang ◽  
Yong Li ◽  
Yihang Liu
Keyword(s):  
Fourier Transform ◽  
High Speed ◽  
Shape Measurement ◽  
Measurement Technology ◽  
Reconstruction Process ◽  
Measured Object ◽  
3D Shape ◽  
3D Shape Measurement ◽  
Fourier Transform Profilometry ◽  
Dynamic Objects

A novel high-speed 3D shape measurement technology called temporal Fourier transform profilometry (TFTP for short) is proposed by combining the merits of Fourier transform profilometry (FTP) and phase-measuring profilometry (PMP). Instead of using the digital light projector, a mechanical projector is employed to generate multi-period phase-shifting fringe patterns sequentially. During the reconstruction process, the phase value of each pixel is calculated independently along the temporal axis and no spectrum filtering operation is performed in a spatial domain. Therefore, high-frequency components containing the detailed information of the measured object effectively remain. The proposed method is suitable for measuring isolated dynamic objects. Only one frame of deformed fringe pattern is required to retrieve one 3D shape of the measured object, so it has the obvious advantage if measuring the dynamic scene at a high speed. A low-cost self-made mechanical projector with fast projection speed is developed to execute the principle-proof experiments, whose results demonstrate the feasibility of measuring isolated dynamic objects.

scholarly journals Applications Of Tunable Mid-Infrared Plasmonic Square-Nanoring Resonator Based On Graphene Nanoribbon

2021 ◽  
Author(s):  
Morteza Janfaza ◽  
Mohammad Ali Mansouri-Birjandi ◽  
Alireza Tavousi
Keyword(s):  
Chemical Potential ◽  
Graphene Nanoribbons ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Optical Computing ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Mid Infrared ◽  
Band Pass ◽  
Basic Blocks

Abstract In this work, different structures are designed based on graphene square-nanoring resonator (GSNR) and simulated by the three-dimensional finite-difference time-domain (3D-FDTD) method. Depending on the location and number of graphene nanoribbons (GNR), the proposed structures can be utilized as a band-pass filter, wavelength demultiplexer, or power splitter in the mid-infrared (MIR) wavelengths. The tunability of the suggested assemblies is easily controlled by changing the dimensions and/or the chemical potential of the GSNRs. Benefiting from the nanoscale and ultra-compact GNRs, these structures can be proposed as basic blocks for optical computing and signal processing in the MIR region.

scholarly journals Filtering Sinyal Suara Gitar Menggunakan Band Pass Filter

2019 ◽  
Vol 4 (1) ◽  
pp. 57-60
Author(s):  
Adhif Rayana AR ◽  
Wiwid Andriani
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Band Pass ◽  
Analog Domain

Pada bidang komunikasi bahwa sinyal suara asli tanpa derau (noise) dikatakan penting dikarenakan memberikan informasi dengan jelas, jika sinyal suara asli telah tercampur derau (noise) maka sinyal suara tersebut menjadi lemah dan akhirnya hilang/tidak berguna. Sehingga untuk mengatasi sinyal suara yang telah berderau (noise) tersebut perlu dilakukan penapisan (filtering) terhadap sinyal suara asli agar sinyal suara asli dapat diterima dengan baik oleh di pendengar/penerima informasi. Maka dari itu penelitian ini dilakukan untuk penapisan (filtering) terhadap sinyal suara asli gitar yang telah tercampur derau (noise) menggunakan metode band pass filter. Dimana metode band pass filter berfungsi untuk meloloskan sinyal terhadap range frekuensi diatas frekuensi batas bawah (fL) dan dibawah frekuensi batas atas (fH). Pada penelitian tersebut metode band pass filtering diterapkan pada file suara gitar berextensi .wav, kemudian hasil filtering dilakukan pembangkitan pada suara asli gitar. Dan dalam proses enkripsi, sinyal informasi yang berupa sinyal analog (domain waktu) dikonversikan kedalam domain frekuensi menggunakan algoritma Fast Fourier Transform (FFT). Dan penapisan (filter) dilakukan dengan filter band pass. Hasil penapisan diperoleh suatu ‘Grafik’ maupun ‘Suara’ yang mendekati Grafik dan Suara asli. Namun demikian perbandingan suara asli dan hasil filtering (penapisan).  

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