Reconstruction of freeform surfaces for metrology
Article dans une revue sans comité de lecture
Date
2014Journal
Journal of Physics: Conference SeriesAbstract
The application of freeform surfaces has increased since their complex shapes closely express a product's functional specifications and their machining is obtained with higher accuracy. In particular, optical surfaces exhibit enhanced performance especially when they take aspheric forms or more complex forms with multi-undulations. This study is mainly focused on the reconstruction of complex shapes such as freeform optical surfaces, and on the characterization of their form. The computer graphics community has proposed various algorithms for constructing a mesh based on the cloud of sample points. The mesh is a piecewise linear approximation of the surface and an interpolation of the point set. The mesh can further be processed for fitting parametric surfaces (Polyworks® or Geomagic®). The metrology community investigates direct fitting approaches. If the surface mathematical model is given, fitting is a straight forward task. Nonetheless, if the surface model is unknown, fitting is only possible through the association of polynomial Spline parametric surfaces. In this paper, a comparative study carried out on methods proposed by the computer graphics community will be presented to elucidate the advantages of these approaches. We stress the importance of the pre-processing phase as well as the significance of initial conditions. We further emphasize the importance of the meshing phase by stating that a proper mesh has two major advantages. First, it organizes the initially unstructured point set and it provides an insight of orientation, neighbourhood and curvature, and infers information on both its geometry and topology. Second, it conveys a better segmentation of the space, leading to a correct patching and association of parametric surfaces.
Files in this item
- Name:
- Reconstruction of Freeform ...
- Size:
- 1.537Mb
- Format:
- Description:
- Article de revue
Related items
Showing items related by title, author, creator and subject.
-
Article dans une revue avec comité de lectureEL HAYEK, Nadim; NOUIRA, Hichem; ANWER, Nabil; DAMAK, Mohamed; GIBARU, Olivier (Korean Society of Precision Engineering,, 2014)Both contact and non-contact probes are often used in dimensional metrology applications, especially for roughness, form and surface profile measurements. To perform such kind of measurements with a nanometer level of ...
-
Article dans une revue avec comité de lectureIn the framework of form characterization of aspherical surfaces, European National Metrology Institutes (NMIs) have been developing ultra-high precision machines having the ability to measure aspherical lenses with an ...
-
Article dans une revue avec comité de lectureEL HAYEK, Nadim; NOUIRA, Hichem; ANWER, Nabil; DAMAK, Mohamed; BOURDET, Pierre; GIBARU, Olivier (ELSEVIER, 2014)Aspheric surfaces have become widely used in various fields ranging from imaging systems to energy and biomedical applications. Although many researches have been conducted to address their manufacturing and measurement, ...
-
Communication sans acteIn the context of coordinate metrology and reverse engineering, freeform curve reconstruction from unorganized data points still offers ways for improvement. Geometric convection is the process of fitting a closed shape, ...
-
Article dans une revue avec comité de lectureVISSIERE, Alain; NOUIRA, Hichem; DAMAK, Mohamed; GIBARU, Olivier; DAVID, Jean-Marie (IOP Publishing, 2012)Advanced manufacturing processes require improving dimensional metrology applications to reach a nanometric accuracy level. Such measurements may be carried out using conventional highly accurate roundness measuring machines. ...