Fringe projection simulation software for 3D shape measurements

Optics and Lasers in Engineering, 2010

a b s t r a c t As technologies evolve, there have been high demands for the three-dimensional (3D) shape measurement techniques to posses the following combined technical features: high accuracy, fast speed, easy implementation, capability of measuring multiple objects as well as measuring complex shapes. Generally, the existing techniques can satisfy some of the requirements, but not all of them. This paper presents four practical considerations in fringe projection profilometry (FPP) based 3D shape measurements, along with simple but robust solutions, including gamma correction of digital projection, arbitrary setup of system components, phase unwrapping with multi-frequency fringes, and system calibration with a least-squares inverse approach. The validity and practicability of the FPPbased 3D shape measurement technique using the four corresponding technical approaches have been verified by experiments. The presented technique is capable of satisfying the various critical demands in enormous scientific and engineering applications.

Optics Letters, 2007

A mathematical description of the absolute out-of-plane height distribution in 3D shape measurement with an arbitrarily arranged fringe projection profilometry system is presented, and a corresponding algorithm is proposed to determine the parameters required for accurate 3D shape determination in practical applications. The proposed technique requires neither a specific and precise experimental setup nor a manual measurement of geometric parameters, and it yields high measurement accuracies while allowing the system components to be arbitrarily set and positioned. Computer simulations and a real experiment have been conducted to verify the validity of the technique.

Optics Express, 2006

The out-of-plane shape determination in a generalized fringe projection profilometry is presented. The proposed technique corrects the problems in existing approaches, and it can cope well with the divergent illumination encountered in the generalized profilometry. In addition, the technique can automatically detect the geometric parameters of the experimental setup, which makes the generalized fringe projection profilometry simple and practical. The concept was verified by both computer simulations and actual experiments. The technique can be easily employed for out-of-plane shape measurements with high accuracies.

Optical Engineering, 2003

We present a method to obtain profilometry of a suitable object by fringe projection. The method is appropriate to the case of large objects as compared to the distance from the illuminating source, that is, a nonconstant equivalent wavelength. We develop an experiment to laterally displace a set of fringes on a sphere and obtain quantitative results. There are several orientation parameters involved in the method, and a minimization algorithm is developed to adjust the values of some of them. A series of numerical experiments are performed on this method to test its accuracy under various circumstances. We show that the method can currently attain precisions of Ϸ eq /80 ( eq stands for equivalent wavelength) and identify possible sources of error.

Optik, 2018

Fringe projection profilometry is an efficient approach for shape reconstruction. An essential step in fringe projection profilometry is the calibration of both the transverse (axial) and longitudinal (depth) directions. In the present work, a longitudinal calibration method for fringe projection profilometry is proposed. In the proposed approach a stepped board is used to calibrate the measurement system in a single scan. Each step of the board represents a different position and therefore only a single scan is required to calibrate the measurement system. The proposed approach neither requires a translating stage nor taking multiple scans of a reference board at various positions, as in traditional techniques. The proposed approach was validated by reconstructing a real object and evaluating its main dimension. Experimental results show the reliability and effectiveness of the proposed method. Measurement errors evaluated for a system calibrated using the proposed approach are relatively smaller than those obtained using a traditional calibration approach. The proposed approach is considerably faster than traditional calibration methods besides being much simpler to implement for onsite measurements.

This research proposes a simplified geometric model for a generic projector application in digital fringe profilometry. Reported works have high number of model parameters and project at slanted angles. This increases complexity of the calibration processes and causes. The arrangement also complicates the determination of model parameters as the inner details of a projector are not revealed to end user. The proposed model enables simpler calibration by determining only three parameters, eliminating inconsistency of fringe width, and applying a more suitable light path configuration for any generic projector available off-the-shelf. Three conditions must be met for the model to function appropriately, which includes (1) the camera optical axis and projector reference line must be orthogonal to the reference plane, (2) the measured object must be within the overlapped light path area between the camera and projector, and (3) the end of the image acquisition area must be placed before the reference line of the projector. Experimental result shows that the model is capable of reconstructing object with errors recorded at 0.07 ± 0.04 mm, 0.10 ± 0.04 mm and 2.63 ± 0.20 mm for flat, slanted and curved surfaces, respectively.

IEEE Transactions on Instrumentation and Measurement, 2000

An original procedure is presented for the calibration of fringe-projection-based 3-D vision systems. The proposed approach estimates both the phase-to-depth and transverse relationships by directly measuring the phase maps for only three planes placed within the calibration volume and then estimating the phase maps for a number of other "virtual planes." Experimental tests conducted on a fringe projection system show the effectiveness of the proposed procedure.

Measurement Science & Technology, 2006

We present a whole-field, 3D optical digitizer based on phase profilometry and on absolute calibration, which performs shape measurement through the projection of a single pattern of Ronchi fringes, and an absolute calibration of the optical head. A suitably developed procedure, based on accurate fringe analysis, implements phase extraction and allows univocal indexing of the field of view. Accurate models express, in a global reference system, both extrinsic and intrinsic parameters of the camera-projector pair. Proper calibration is performed for lens distortion compensation, and to obtain the absolute measurement of the shapes within a global reference system. The technique requires the acquisition of a single image, shows good robustness against fine variations of the fringe period and adapts well to the measurement of free-form shapes in a very short time. The system is portable, fully reconfigurable depending on the measurement requirements and suitable for a low-cost implementation. In this paper, we present the phase extraction method and the system calibration, and highlight the measurement performance of the digitizer in different set-ups, using free-form objects requiring multi-view acquisition.

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

In this paper, a generalized analysis model for fringe pattern profilometry is presented. The new analysis model is derived mathematically, which describes the essential relationships between projected and deformed fringe patterns. With generalized analysis model, the projected fringe patterns used for profilometry can be arbitrary rather than being limited to be sinusoidal as those for the conventional approaches. Meanwhile, based on the proposed generalized model, a new algorithm is presented to reconstruct three-dimensional surfaces. Computer simulation results show that compared with the conventional model for fringe pattern profilometry, the generalized model and the proposed algorithm can significantly improve the three-dimensional reconstruction accuracy, especially when the projected fringe pattern is distorted by some unknown factors.

Optics and Lasers in Engineering, 2006

A precise interferometric method for three-dimensional surface measurements in a wide dynamic range is presented. The method is based on symmetrical two-spacing projection phase-stepping interferometry. Two approaches are proposed-one with double symmetrical illumination and the other with double symmetrical observation-which reduce influence of shadowing at investigation of complex surfaces and allow absolute coordinates estimation. The theoretical background, experimental check as well as accuracy and sensitivity assessment of the method are discussed. The proposed technique is especially useful for remote, non-destructive in-situ measurements of real objects-for example historical objects and monuments. r (J. Harizanova), [email protected] (V. Sainov).