In this paper, we present an optical profilometric technique for 3D shape measurement--Fourier Transform Profilometry (FTP). In contrast to other optical techniques, the grating pattern will in its spatial frequency fields as well as in its space-signal fields which projected onto the object surface and was Fourier-transformed and processed. This technique only requires a single fringe pattern up to no more than two to reproduce 3D object shape. FTP has a much higher sensitivity to the fringe quality than other techniques. We design a system which has a high-resolution system composed of a video projector and a digital camera. A fringe pattern of programming by computer is projected onto the free surface and its diagram is recorded by the camera. The deformed fringe pattern arising from the surface deformations is later compared to the unreformed (reference) one, leading to a phase map from which the free surface can be reconstructed after some series of processes.
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.