Hugues Favreliere

Bio: Hugues Favreliere is an academic researcher from University of Savoy. The author has contributed to research in topics: Polynomial texture mapping & Rendering (computer graphics). The author has an hindex of 10, co-authored 43 publications receiving 409 citations. Previous affiliations of Hugues Favreliere include Polytech'Savoie.

Modeling of 2D and 3D Assemblies Taking Into Account Form Errors of Plane Surfaces

Abstract: The tolerancing process links the virtual and the real worlds. From the former, tolerances define a variational geometrical language (geometric parameters). From the latter, there are values limiting those parameters. The beginning of a tolerancing process is in this duality. As high precision assemblies cannot be analyzed with the assumption that form errors are negligible, we propose to apply this process to assemblies with form errors through a new way of allowing to parameterize forms and solve their assemblies. The assembly process is calculated through a method of allowing to solve the 3D assemblies of pairs of surfaces having form errors using a static equilibrium. We have built a geometrical model based on the modal shapes of the ideal surface. We compute for the completely deterministic contact points between this pair of shapes according to a given assembly process. The solution gives an accurate evaluation of the assembly performance. Then we compare the results with or without taking into account the form errors. When we analyze a batch of assemblies, the problem is to compute for the nonconformity rate of a pilot production according to the functional requirements. We input probable errors of surfaces (position, orientation, and form) in our calculus and we evaluate the quality of the results compared with the functional requirements. The pilot production then can or cannot be validated.

Multi Scale Modal Decomposition of Primary Form, Waviness and Roughness of Surfaces

Abstract: This article introduces an innovative method for the multi-scale analysis of high value-added surfaces, which consists of applying a method based on a new parameterization. This kind of surface parameterization refers to natural modes of vibration, and is therefore named modal parameterization. It allows us to characterize the form, waviness and roughness defects of a surface. This parameterization opens up new fields of analysis, such as the appearance quality of surfaces. It is thereby possible to decompose a measured surface in a vector basis, of which vectors are represented by plane natural eigenmodes sorted by frequency and complexity. Different filtering operations can then be produced, such as extracting the primary form of the surface. To analyze the perceived quality of surfaces, these investigations focus on two approaches: that appearance defects have small periodicity, and that there is a link between curvatures and the visual impact of an anomaly. This methodology is applied to two prestige lighters, whose surfaces were measured by extended field confocal microscopy. Moreover, a prospect of this work is to develop an augmented-reality-type monitoring tool for sensory experts.

Outlier filtering: a new method for improving the quality of surface measurements

Abstract: This paper introduces a new filtering technique that aims to improve the quality of measured surface data by removing measurement artefacts, such as spikes and batwings, that impact the data analysis. The methods currently available for measuring surfaces allow a large number of heights on a surface to be measured with high lateral and vertical resolution. However, measured data often contain outliers, which take the form of sharp peaks on the surface (Dirac type) and are particularly common in optical measuring methods. By nature, these peaks cannot belong to a 'real' surface; thus, an outlier filtering step is necessary and should be the initial preparation step for the measured data prior to any further analysis. The measurement artefacts can strongly influence the topographic characterization parameters and adversely influence quality control efforts as well as functional analyses for discrimination and correlation of the surfaces. The proposed method makes the filtering of such outliers easier and more effective with criteria linked to the standard deviation (Peirce method) and associated with a modal form-filtering method that is independent of the presence of these peaks. The filter is then applied to the surface at different scales; thus, the method is scale sensitive and improves the filter efficiency. This new method is applied to surface data that were measured by optical means from different surfaces. The surfaces were measured with a 3D-measuring laser microscope and laser scanning confocal microscopy. The results of testing these examples will determine the extent to which this method can improve the quality of measured data and thus influence the results of further analyses.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

A reflectance model for computer graphics

Abstract: This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic.