Three-dimensional scanning of specular and diffuse metallic surfaces using an infrared technique

For the past two decades, the need for three-dimensional (3-D) scanning of industrial objects has increased significantly and many experimental techniques and commercial solutions have been proposed. However, difficulties remain for the acquisition of optically non-cooperative surfaces, such as transparent or specular surfaces. To address highly reflective metallic surfaces, we propose the extension of a technique that was originally dedicated to glass objects. In contrast to conventional active triangulation techniques that measure the reflection of visible radiation, we measure the thermal emission of a surface, which is locally heated by a laser source. Considering the thermophysical properties of metals, we present a simulation model of heat exchanges that are induced by the process, helping to demonstrate its feasibility on specular metallic surfaces and predicting the settings of the system. With our experimental device, we have validated the theoretical modeling and computed some 3-D point clouds from specular surfaces of various geometries. Furthermore, a comparison of our results with those of a conventional system on specular and diffuse parts will highlight that the accuracy of the measurement no longer depends on the roughness of the surface

Application of 3D scanning techniques to the process control of forged parts

L’objectif de ces travaux de thèse est la conception et le développement d’un système de caractérisation tridimensionnelle de pièces forgées de grande dimension portées à haute température. Les travaux se basent sur de nombreuses thématiques telles que l’acquisition tridimensionnelle, l’extraction, la segmentation et le recalage de primitives 3D. Nous présentons tout d’abord les limites des systèmes de caractérisation de pièces forgées cités dans la littérature. Dans la deuxième partie, nous présentons la réalisation du système de caractérisation de pièces forgées, constitué de deux scanners temps de vol (TOF). Nous présentons également le simulateur de numérisation par scanner TOF qui nous permet de nous affranchir des contraintes industrielles (temps, difficulté de manœuvres) pour positionner les deux scanners. La troisième partie est consacrée à l’extraction des primitives 3D. Nous avons traité deux types de primitives : viroles et sphères avec deux approches différentes : méthode supervisée et méthode automatique. La première approche basée sur une méthode de croissance de région et de contour actif, permet d’extraire des formes extrudées complexes. Des problèmes d’ergonomie du système nous ont conduits à développer une deuxième approche, basée sur l’image de Gauss et l’extraction d’ellipse, qui permet l’extraction automatique de formes cylindriques ovales ou circulaires. Nous présentons également quatre méthodes d’extraction automatique de sphères basées sur des approches heuristiques : RANSAC (RANdom SAmple Consensus), algorithme génétique et algorithme génétique par niche. Dans la quatrième partie, nous étudions les différentes approches de recalage de données 3D traitées : le calibrage basé sur les cibles artificielles et le recalage fin basé sur l’algorithme ICP. Pour conclure, nous présentons la réalisation d’un système complet de caractérisation tridimensionnelle de pièces forgées de grande dimension. Ensuite, nous comparons les performances et les limites de ce système avec les systèmes de caractérisation cités dans la littérature.The main objective of this Phd project is to conceive a machine vision system for hot cylindrical metallic shells diameters measurement during forging process. The manuscript is structured by developing in the first chapter the state of the art and the limits of hot metallic shells measurement systems suggested in literature. Our implemented system which is based on two conventional Time Of Flight (TOF) laser scanners has been described in the same chapter along, chapter two, with presentation of its respective numerical simulator. Simulation series have been done using the digitizing simulator and were aimed to determine the optimal positions of the two scanners without any industrial constraints (time, difficulty of operations). The third part of the manuscript copes with 3D primitives extraction. Two major types of approaches have been studied according to the primitive’s form (cylinders or spheres) to be extracted: supervised method and automatic method. The first approach, based on a growing region method and active contour, enables to extract complex extruded forms; while problems of ergonomics have been solved using automatic methods that have been carried out along the programme research. The proposed methods consist in automatically extracting: oval or circular cylindrical forms, using Gauss map associated with ellipse extraction techniques : spherical forms, using heuristic approaches such as RANdom SAmple Consensus RANSAC, Genetic Algorithm (GA) and Niche Genetic Algorithm (NGA). Two varieties of 3D data registration approach have been presented and discussed in chapter 4: the registration based on the artificial targets and the fine registration based on algorithm ICP. A complete system for three-dimensional characterization of hot cylindrical metallic shells during forging process has been implemented and then compared with existing systems in order to identify its performances and limits in conclusion

Application des techniques de numérisation tridimensionnelle au contrôle de process de pièces de forge

L objectif de ces travaux de thèse est la conception et le développement d un système de caractérisation tridimensionnelle de pièces forgées de grande dimension portées à haute température. Les travaux se basent sur de nombreuses thématiques telles que l acquisition tridimensionnelle, l extraction, la segmentation et le recalage de primitives 3D. Nous présentons tout d abord les limites des systèmes de caractérisation de pièces forgées cités dans la littérature. Dans la deuxième partie, nous présentons la réalisation du système de caractérisation de pièces forgées, constitué de deux scanners temps de vol (TOF). Nous présentons également le simulateur de numérisation par scanner TOF qui nous permet de nous affranchir des contraintes industrielles (temps, difficulté de manœuvres) pour positionner les deux scanners. La troisième partie est consacrée à l extraction des primitives 3D. Nous avons traité deux types de primitives : viroles et sphères avec deux approches différentes : méthode supervisée et méthode automatique. La première approche basée sur une méthode de croissance de région et de contour actif, permet d extraire des formes extrudées complexes. Des problèmes d ergonomie du système nous ont conduits à développer une deuxième approche, basée sur l image de Gauss et l extraction d ellipse, qui permet l extraction automatique de formes cylindriques ovales ou circulaires. Nous présentons également quatre méthodes d extraction automatique de sphères basées sur des approches heuristiques : RANSAC (RANdom SAmple Consensus), algorithme génétique et algorithme génétique par niche. Dans la quatrième partie, nous étudions les différentes approches de recalage de données 3D traitées : le calibrage basé sur les cibles artificielles et le recalage fin basé sur l algorithme ICP. Pour conclure, nous présentons la réalisation d un système complet de caractérisation tridimensionnelle de pièces forgées de grande dimension. Ensuite, nous comparons les performances et les limites de ce système avec les systèmes de caractérisation cités dans la littérature.The main objective of this Phd project is to conceive a machine vision system for hot cylindrical metallic shells diameters measurement during forging process. The manuscript is structured by developing in the first chapter the state of the art and the limits of hot metallic shells measurement systems suggested in literature. Our implemented system which is based on two conventional Time Of Flight (TOF) laser scanners has been described in the same chapter along, chapter two, with presentation of its respective numerical simulator. Simulation series have been done using the digitizing simulator and were aimed to determine the optimal positions of the two scanners without any industrial constraints (time, difficulty of operations). The third part of the manuscript copes with 3D primitives extraction. Two major types of approaches have been studied according to the primitive s form (cylinders or spheres) to be extracted: supervised method and automatic method. The first approach, based on a growing region method and active contour, enables to extract complex extruded forms; while problems of ergonomics have been solved using automatic methods that have been carried out along the programme research. The proposed methods consist in automatically extracting: oval or circular cylindrical forms, using Gauss map associated with ellipse extraction techniques : spherical forms, using heuristic approaches such as RANdom SAmple Consensus RANSAC, Genetic Algorithm (GA) and Niche Genetic Algorithm (NGA). Two varieties of 3D data registration approach have been presented and discussed in chapter 4: the registration based on the artificial targets and the fine registration based on algorithm ICP. A complete system for three-dimensional characterization of hot cylindrical metallic shells during forging process has been implemented and then compared with existing systems in order to identify its performances and limits in conclusion.DIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

3D Scanning of specular and diffuse metallic surfaces using an infrared technique

International audienceFor the past two decades, the need for 3D Scanning of industrial objects has increased significantly. Therefore, many experimental techniques and commercial solutions have been proposed. However, difficulties remain for the acquisition of optically non-cooperative surfaces, such as transparent or specular surfaces. To address highly reflective metallic surfaces, we propose the extension of a technique that was originally dedicated to glass objects. In contrast to conventional active triangulation techniques that measure the reflection of visible radiation, we measure the thermal emission of a surface, which is locally heated by a laser source. Considering the thermophysical properties of metals, we present a simulation model of heat exchanges that are induced by the process, helping to demonstrate its feasibility on specular metallic surfaces and predicting the settings of the system. With our experimental device, we have validated the theoretical modeling and computed some 3D point clouds from specular surfaces of various geometries. Furthermore, a comparison of our results with those of a conventional system on specular and diffuse parts will highlight that the accuracy of the measurement no longer depends on the roughness of the surface

3D reconstruction of hot metallic surfaces for industrial part characterization

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3D characterization of hot metallic shells during industrial forging

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3D dimensional measurement of large hot metallic shells

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3D laser system for shell dimension measurement during forging

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