High-speed Fourier transform profilometry for reconstructing objects having arbitrary surface colours

Abstract

In this paper, Fourier transform profilometry (FTP) using a colour fringe selection technique for accurate phase map reconstruction is newly proposed to overcome the limitation of FTP in measuring objects having arbitrary surface colours. The sinusoidal colour fringe pattern is encoded to form a unique colour pattern for projecting onto the object’s surface, and its reflected deformed fringe image is taken using a triple-colour CCD camera and rapidly processed by the developed FTP method employing a novel band-pass filter. A new 3D vision system is capable of measuring objects with a high speed of up to 60 frames s − 1. To reconstruct the 3D profile of an object having arbitrary surface colours, an innovative strategy is developed to identify the colour channel of the detected fringe pattern with the best modulation transfer function (MTF) for retrieving accurate phase maps. The experimental results demonstrate that the system has the capability to acquire 3D maps at a high speed while the measurement accuracy of the developed method is substantially better than that of the traditional FTP method. By measuring the standard step heights in a repeatability test, it is confirmed that a maximum measured error can be controlled to less than 2.8% of the overall measuring depth range.

Point-to-point coupling and imbalance correction in color fringe projection profilometry based on multi-confusion matrix

“…For dynamic measurement, FTP is the representative singleshot transform method which is well suitable for dynamic 3D shape measurement. However, due to the limitation of spectrum aliasing, FTP method [31][32][33] is difficult to measure objects with sharp edges, abrupt change or non-uniform reflectivity. Compared with the FTP method, the multi-frame methods [34,35] are used more widely in dynamic scene measurement because of its high precision and robust.…”

Real-time structured light profilometry: a review

“…Even when implemented on parallel hardware, windowed FTP techniques have been reported to be limited to 4 frames per second for maps of 256 × 256 pixels [123]. Furthermore, the measurement accuracy of single-shot techniques is generally determined by the uniform, color-independent reflection profile of the measurement target surface [124]. To reduce the effect of cross-talk between different color channels and thereby to minimize its adverse effect on axial resolution, extra color decoupling calculations are required.…”

3D shape measurement for moving scenes using an interlaced scanning colour camera

“…In the measuring method using the structured light, phase measuring profilometry (PMP) and Fourier transform profilometry (FTP) have been paid many attentions and further researched. FTP provides phase information from a single-frame fringe pattern, and is well-suited for single snapshot 3D shape data acquisition, so it is popular for the dynamic shape measurement; but its accuracy is not very high, and the restored shape for a spatial isolated or abrupt object is imperfect [2][3][4][5][6][7]. PMP is based on the use of the grating projection and digital phaseshifting techniques, and regarded as a point-to-point operation.…”