Analysis of different camera calibration methods on a camera-projector measuring system

The accuracy of metrology equipment formed by a camera-projector pair depends directly on the calibration procedure used. This kind of equipment allows to perform the calibration by two different approaches: as a whole system or separately. The most common approach is the second one: conventional calibration. Studies show that the uncertainty of the camera parameters from its calibration propagates to the projector parameters. The objective of this study is to have a clear comprehension of the relationships between the camera and projector parameters and of how uncertainty is propagated. This will be done by using a camera previously calibrated by Tsai, Zhang or Direct Linear Calibration (DLC) methods, followed by the calibration of the projector using DLC

A Novel Digital Discrete Manufacturing to Build up a 3D-Object

The paper present novel digital fabrication process that assembles building blocksto create a three-dimensional object. The system consists of an assembly robot and afabrication head installed at its tip. The head, consists of a vacuum gripper, an adhesiveextruder, and a camera, and is thus capable of gripping and releasing a building block,applying an adhesive, and determination of the position of things in the process. Thecalibration process and the design and build workflow for this technique are mentioned inthe paper. The process is a discrete fixtureless manufacturing process that gives faster speed,compared to both additive and subtractive manufacturing processes. Tiny mosaic pieces areused as building blocks and fabrication of a curved bridge model is used to demonstratehow this process works and its performance

Automated aircraft dent inspection via a modified Fourier transform profilometry algorithm

The search for dents is a consistent part of the aircraft inspection workload. The engineer is required to find, measure, and report each dent over the aircraft skin. This process is not only hazardous, but also extremely subject to human factors and environmental conditions. This study discusses the feasibility of automated dent scanning via a single-shot triangular stereo Fourier transform algorithm, designed to be compatible with the use of an unmanned aerial vehicle. The original algorithm is modified introducing two main contributions. First, the automatic estimation of the pass-band filter removes the user interaction in the phase filtering process. Secondly, the employment of a virtual reference plane reduces unwrapping errors, leading to improved accuracy independently of the chosen unwrapping algorithm. Static experiments reached a mean absolute error of ∼0.1 mm at a distance of 60 cm, while dynamic experiments showed ∼0.3 mm at a distance of 120 cm. On average, the mean absolute error decreased by ∼34%, proving the validity of the proposed single-shot 3D reconstruction algorithm and suggesting its applicability for future automated dent inspections.Cranfield IVHM Centr