In the field of quality control, automatic inspection systems can greatly improve the production process, both in terms of precision and time consumption. In particular, for small superficial defect detection, high resolution techniques are required for surface profile measurement and 3D modeling with errors of units of microns. Among active systems for precise measurements, those based on laser triangulation scanners are very promising since they are contactless and not invasive, and at the same time it provides high precision and fast measurements. In the last decade, laser triangulation scanners have been widely used for quality inspection, surface profile measurement, 3D modeling and reverse engineering applications. These systems use a camera and a laser light to model 3D objects as the appearance of the laser spot changes according to the distance between the light source and the object surface. The design of a laser triangulation scanner presents many challenges as the project of the optical routing, the detection of the laser spot in the camera image plane, and the overall system calibration greatly affect the measure ability. Moreover, issues such as the laser reflective properties on the object surface, speckle noise, occlusions and sub-pixel precision in the detection of laser stripe peaks are fundamental to increase the precision of the final measurement. The objective of this project is the development of a 3D reconstruction system for the detection of surface defect with high precision. The system is based on a laser triangulation scanner that, by using an innovative acquisition procedure, overcomes the occlusion problems due to the presence of grooves on the object surface. In particular, the proposed system has a resolution of 15 µm which, to the best of our knowledge, has never been reached by using a standard laser triangulation scanner.
Study and Development of a Prototypal System for 3D Reconstruction of Industrial Toolmakers
Ettore Stella
2012
Abstract
In the field of quality control, automatic inspection systems can greatly improve the production process, both in terms of precision and time consumption. In particular, for small superficial defect detection, high resolution techniques are required for surface profile measurement and 3D modeling with errors of units of microns. Among active systems for precise measurements, those based on laser triangulation scanners are very promising since they are contactless and not invasive, and at the same time it provides high precision and fast measurements. In the last decade, laser triangulation scanners have been widely used for quality inspection, surface profile measurement, 3D modeling and reverse engineering applications. These systems use a camera and a laser light to model 3D objects as the appearance of the laser spot changes according to the distance between the light source and the object surface. The design of a laser triangulation scanner presents many challenges as the project of the optical routing, the detection of the laser spot in the camera image plane, and the overall system calibration greatly affect the measure ability. Moreover, issues such as the laser reflective properties on the object surface, speckle noise, occlusions and sub-pixel precision in the detection of laser stripe peaks are fundamental to increase the precision of the final measurement. The objective of this project is the development of a 3D reconstruction system for the detection of surface defect with high precision. The system is based on a laser triangulation scanner that, by using an innovative acquisition procedure, overcomes the occlusion problems due to the presence of grooves on the object surface. In particular, the proposed system has a resolution of 15 µm which, to the best of our knowledge, has never been reached by using a standard laser triangulation scanner.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
