Papers by Keyword: Structured Light

Abstract: The advantages of non-contact digitising systems over contact systems are undeniable. They allow capturing more information per unit of time with less accessibility problems and without alter the digitised surface. Although many of these systems have been developed with the aim of replacing contact systems in metrological verification tasks, generalist techniques such as photogrammetry, structured light, etc., have been developed over the years for digitising archaeological remains, works of art or living biological systems, among others. As is the case for non-contact measurement-oriented systems, for these generalist systems there are still difficulties in positioning them along a metrological traceability chain if they are required for any kind of measurement. This is due to the lack of specific standards, as well as the strong influence of the optical properties of the digitised surface on the quality of the results obtained. It is therefore necessary to develop calibration procedures and characterisation work to analyse this influence. The aim of this work is to characterise the metrological performance of one of these generalists structured light devices, Einscan-SP by Shining 3D, in the digitising of different calibration spheres made of different materials (WC, Al₂O₃, ZrO₂, etc.) with different surface finishes (shot-blasted, polished, coated). As quality indicators, the number of points captured, the quality of the point cloud as well as the dimensional and geometrical deviation from the results obtained with a high-performance contact measurement system shall be used. Apart from the raw data, the influence of applying filtering to the captured clouds is analysed. The results of this work allow recommendations to be made regarding the material and finish of the spheres to be used, as well as the filtering to be applied, if necessary, in order to assess the metrological performance of this type of equipment.

Abstract: The paper deals with a description of the creation of CAD model (file format .IGES) based on polygon mesh (file format .STL) obtained by 3D scanning. On the basis of the imported polygon mesh into Reverse Engineering software, it is possible to create surface (or solid) CAD model. For CAD model created from a polygon mesh, a model of screw propeller was chosen. The paper also presents a color deviation map acquired by comparison between a polygon mesh and a CAD model. The 3D digitizing was performed by 3D scanner GOM ATOS II SO TripleScan; GOM ATOS Professional v7.5 SR2 software was used for processing of the scanned data and Delcam PowerSHAPE 2015 CAD software was used for reverse modeling.

Abstract: In line structured light three-dimensional measurement systems, the position of shifted light in the structure light image reflects the three-dimensional profile information of the object. In this paper, according to the characteristics of structured light image, a approach of separating shifted pixels is proposed, and successfully extracts structured light image two-dimensional data with related mathematical methods, which contributes to the foundation for structured light three-dimensional reconstruction of three-dimensional measurement system work.

Abstract: In this paper, some tests was performed to evaluate the effect of scanning depth of field on the measurement error and the density of the point cloud obtained from the developed non-contact 3D scanner by measurement error of about ±0.05mm, which was taken from a single digital camera and a 3LCD video projector as a source projecting the structured light pattern. To perform this analysis, the scanning depth changes occurred in steps. However, due to the effect that the video projector focus has on the sharpness of the projected image pattern and consequently the measurement noise created, the tests were repeated again with the change in focus at every step. The experimental results suggest the need to define the optimum scanning depth (less than 60cm), to provide a stable and acceptable precision, and shows the great effect of scanning depth of field and sharpness of the projected pattern on the amount of measurement noise and density of the points cloud.

Abstract: In this research, an automated robotic bin-picking system employing active vision for picking up randomly distributed plumbing parts is presented. This system employs an actively-controlled single eye-in-hand system to observe structured light projected onto a set of plumbing parts in a bin. By using image processing and iterative closest point (ICP) algorithms, a single plumbing part that could possibly be taken from the bin is detected. Specifically, by projecting stationary structured light patterns onto the set of plumbing objects, the features on the surfaces of plumbing parts can be reconstructed by actively moving the eye-in-hand camera while performing visual tracking of those features. An effective 3D segmentation technique is employed to extract the point cloud of a single plumbing part that can possibly be grasped successfully. Once the object point cloud is obtained, one needs to determine the coordinate transformation from the end-effector to the selected plumbing part for grasping motion. With the point cloud matching result based on utilizing the ICP algorithm, the position and orientation of the selected plumbing part can be correctly estimated if the deviation of the object point cloud from the model point cloud is small. The control command can thus be given to the robotic manipulator to accomplish the automated bin-picking task. To effectively expand the allowed deviation of the object point cloud, an approximate pose estimation algorithm is employed before performing the ICP algorithm. The proposed approach can virtually estimate any pose of the plumbing part and has been successfully experimented with an industrial manipulator equipped with eye-in-hand single-camera vision and a LCD projector fixed in the work space demonstrating the feasibility and effectiveness. The proposed automated bin-picking system appears to be cost-effective and have great potentials in industrial factory automation applications.

Abstract: Getting the real-time information of spatial data, height and length of weld bead is the key point during the process of grinding and polishing large-scale part. To tackle this problem, a robot visual system is completed by building the double CCD and the laser on the mobile robot. Combining the image search algorithm with the image preprocessing algorithm in time domain, the laser single pixel feature line is obtained. The positions of each point in feature line are optimized by curve fitting so that the right spatial data and dimension are obtained. The result shows the proposed method can provides the precise information of weld bead, and the accuracy of measurement is within 0.15mm, as steady as repeatability.

Abstract: a monocular structure optical grating projection measuring method using multi-frequency phase shifting codec, oral direct access to the tooth preparation method of the digital model, reveals direct access to oral tooth preparation morphology the law of the data.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.Please make the page settings of your word processor to A4 format (21 x 29,7 cm or 8 x 11 inches); with the margins: bottom 1.5 cm (0.59 in) and top 2.5 cm (0.98 in), right/left margins must be 2 cm (0.78 in).

Abstract: The paper deals with utilization of active triangulation method for shape investigation of cutting inserts after wear. For measuring of cutting insert shape a method using the structured light (fringe projection) was used. As a measuring device the optical 3D scanner GOM ATOS II TripleScan SO was used. Cutting inserts with different shapes was measured. With the measurement method mentioned in the paper the accurate shape of the cutting insert can be captured. From the 3D model moreover it is possible to measure the geometrical properties as well as tool wear, plastical deformation, build-up-edge, corner damage and chipping of cutting insert.

Abstract: An improved tripolar pulse width modulation method has been proposed in this paper. According to the linear effect of optical system defocusing, the three-gray-level structured light pattern can be split into two binary ones. With the composite image, the same measurement result as the tripolar method is obtained. Simulation result shows that, under three-step phase shifting method, the error of phase retrieval is greatly eliminated. Thus, the proposed method can achieve better depth reconstruction results than PWM method. Furthermore, both simulation and experimental results show that the measurement range of this method is effectively extended.

Abstract: Structured light extraction is an important problem in 3-D measurement of structured light. Due to traditional structured light extraction methods are mostly applied in small visual field and simple environment. Therefore, a novel method is proposed based on the feature of structured light aiming at the large field and complex surroundings. Firstly, a region of interest (ROI) is obtained through a third sensor in order to reduce calculations and process conveniently. And then, structured light is extracted according to its feature of brightness distribution module and geometrical morphology trait. Experiment shows that this new method not only extracts structured light in such large field with strong background noise well but also reduces the computation to meet real-time requirement.