Fringe projection techniques: Whither we are?

Abstract

During recent years, the use of fringe projection techniques for generating three-dimensional (3D) surface information has become one of the most active research areas in optical metrology. Its applications range from measuring the 3D shape of MEMS components to the measurement of flatness of large panels (2.5 m × .45 m). The technique has found various applications in diverse fields: biomedical applications such as 3D intra-oral dental measurements [1], non-invasive 3D imaging and monitoring of vascular wall deformations [2], human body shape measurement for shape guided radiotherapy treatment [3,4], lower back deformation measurement [5], detection and monitoring of scoliosis [6], inspection of wounds [7,8] and skin topography measurement for use in cosmetology [9,10, 11]; industrial and scientific applications such as characterization of MEMS components [12,13], vibration analysis [14,15], refractometry [16], global measurement of free surface deformations [17,18], local wall thickness measurement of forced sheet metals [19], corrosion analysis [20,21], measurement of surface roughness [22,23], reverse engineering [24,25,26], quality control of printed circuit board manufacturing [27,28,29] and heat-flow visualization [30]; kinematics applications such as measuring the shape and position of a moving object/creature [31,32] and the study of kinematical parameters of dragonfly in free flight [33,34]; biometric identification applications such as 3D face reconstruction for the development of robust face recognition systems [35,36]; cultural heritage and preservation [37,38,39] etc.One of the outstanding features of some of the fringe projection techniques is their ability to provide high-resolution, whole-field 3D reconstruction of objects in a non-contact manner at video frame rates. This feature has backed the technique to pervade new areas of applications such as security systems, gaming and virtual reality. To gain insights into the series of contributions that have helped in unfolding the technique to acquire this feature, the reader is referred to the review articles in this special issue by Song Zhang, and Xianyu Su et al.A typical fringe projection profilometry system is shown in Fig 1. It consists of a projection unit, an image acquisition unit and a processing/analysis unit. Measurement of shape through fringe projection techniques involves (1) projecting a structured pattern (usually a sinusoidal fringe pattern) onto the object surface, (2) recording the image of the fringe pattern that is phase modulated by the object height distribution, (3) calculating the phase modulation by analyzing the image with one of the fringe analysis techniques (such as Fourier transform Figure 1: Fringe projection profilometry system method, phase stepping and spatial phase detection methodsmost of them generate wrapped phase distribution) (4) using a suitable phase unwrapping algorithm to get continuous phase distribution which is proportional to the object height variations, and finally (5) calibrating the system for m...

Frequency-division-multiplexing based period-coded fringe pattern for reliable depth sensing

“…One outstanding feature of this fringe projection method is that it can provide highresolution, whole-field 3D reconstruction of objects [14]. However, the phase unwrapping is inevitable in this algorithm.…”

Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery

“…However, there are a number of methods that have been proposed to facilitate pattern detection through the use of more complex coded patterns, and a number of coding algorithms have been proposed in the literature (e.g. (Albitar et al, 2007;Pavlidis et al, 2007;Chen and Li, 2008;Kawasaki et al, 2008;Gorthi and Rastogi, 2010;Maurice et al, 2011)); processing and display may be achieved in real time. In the case of a mono camera detection, the challenge is to establish the relationship between the pattern generation and the camera parameters, a process that is again generally achieved prior to operation using a calibration target.…”

Determination of height profile from a two-dimensional fringe signal using a two-dimensional continuous wavelet transform

“…In the following years, more advanced measurement systems were designed with Morie and sinusoidal fringe projection techniques and surface profile calculation methods experimented by different integral transforms and phase shifting. Over the years, the importance of fringe projection profilometry has increased in the field of optical measurement and it has been applied in many areas such as biomedical applications like oral and dental measurements, histology, and cell biology, as well as many areas of industry, e.g., quality control, surface measurement, and characterization of microelectromechanical components [2][3][4][5].…”

“…Then this phase information is converted to height from the geometry of the setup. After determining the height of each point on the surface (pixel by pixel) from the reference plane, these are brought together to provide the 3D profile of the object [1,3].…”