Simple and accurate empirical absolute volume calibration of a multi-sensor fringe projection system

Multi-view systems are an effective scheme for solving the problem of a small field-of-view and self-occlusion in optical 3D measurements. However, due to the dispersed distribution of views and the lack of a common field-of-view, the problem of global calibration is difficult and essential. A new method is proposed, by which digital fringe projection and a phase map are used to establish global calibration information. Firstly, fringes are projected to the field of the system. By using a phase unwrapping algorithm, an absolute phase map is obtained. The projector is deemed as the reverse of a camera, which can be calibrated in a similar way to that of the camera. Therefore, the parameters of the cameras, projector and the location of each calibration plane are calculated, and the transformation relationship of adjacent cameras is obtained. Secondly, the phase is used in 3D measurement as well as the global registration of views. Sub-pixel point matching and 3D reconstruction is performed according to the phase map. Global system parameters are optimized by minimizing the reconstruction errors, and precise calibration results can be achieved. With this method, a large-sized calibration target and other auxiliary calibration devices are not required. It is reliable and easy to implement multi-view calibration and reconstruction. The calibration model and calculation processing are simple. The experiment is carried out on a multi-view 3D measurement system. It is shown that high precision multi-view calibration and reconstruction results are obtained.

Section: A Flexible Multi-view Calibration and 3d Measurement Methods...mentioning

confidence: 99%

“…The target has multiple gauge blocks of different heights, which can be observed from all views. In [42], a phase-height table is established to conduct absolute empirical calibration. It is an accurate calibration method for multi-sensor systems.…”

Section: A Flexible Multi-view Calibration and 3d Measurement Methods...mentioning

confidence: 99%

A flexible multi-view calibration and 3D measurement method based on digital fringe projection

Gai

Tang

2019

“…The developed setup comprised of two stereo pairs (four DSLR cameras and two projectors) is shown in figure 3. Other authors [124,125] developed global characterisation methods for multiple camera-projection systems avoiding the pair camera cross-talks by employing particular light bandwidths (i.e. RGB optical colour filters).…”

Section: Characterisation Approachesmentioning

confidence: 99%

Smart optical coordinate and surface metrology

Catalucci

Thompson

Eastwood

et al. 2022

Manufacturing has recently experienced increased adoption of optimised and fast solutions for checking product quality during fabrication, allowing for manufacturing times and costs to be significantly reduced. Due to the integration of machine learning algorithms, advanced sensors and faster processing systems, smart instruments can autonomously plan measurement pipelines, perform decisional tasks and trigger correctional actions as required. In this paper, we summarise the state of the art in smart optical metrology, covering the latest advances in integrated intelligent solutions in optical coordinate and surface metrology, respectively for the measurement of part geometry and surface texture. Within this field, we include the use of a priori knowledge and implementation of machine learning algorithms for measurement planning optimisation. We also cover the development of multi-sensor and multi-view instrument configurations to speed up the measurement process, as well as the design of novel feedback tools for measurement quality evaluation.

“…Gai et al proposed an easy-to-use characterisation of a multiview fringe projection system, where the digital fringe projection and phase maps are used to acquire global characterisation [17]. Gdeisat et al [18] and Deetjen et al [19] developed the global characterisation methods for multiple camera-projection systems, whereby the cross-talk between multiple camera-projector pairs is avoided by using a particular light bandwidth (RGB optical colour filters). Deejtan et al also demonstrated the technique for high-speed 3D reconstruction of a flying bird.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of a multi-view fringe projection system based on the stereo matching of rectified phase maps

Shaheen

Sims-Waterhouse²,

Bointon³

et al. 2021

Multi-view fringe projection systems can be effective solutions to address the limitations imposed by the limited field of view, line-of-sight issues and occlusions when measuring the geometry of complex objects, associated with single camera–projector systems. However, characterisation of a multi-view system is challenging since it requires the cameras and projectors to be in a common global coordinate system. We present a method for characterising a multi-view fringe projection system which does not require the characterisation of the projector. The novelty of the method lies in determining the correspondences in the phase domain using the rectified unwrapped phase maps and triangulating the matched phase values to reconstruct the three-dimensional shape of the object. A benefit of the method is that it does not require registration of the point clouds acquired from multiple perspectives. The proposed method is validated by experiment and comparison with a conventional system and a contact coordinate measuring machine.