Cyclododecane as opcifier for digitalization of archaeological glass

[EN] This paper faces the problem of acquiring archaeological artifacts using triangulation based 3D laser scanners and focusing on reflective/refractive surfaces. This kind of artifacts are mostly made of glass or polished metal, and the properties of their surfaces violate most of the fundamental assumptions made by vision algorithms. Also, the unique and fragile nature of archaeological artifacts adds an extra constraint to the acquisition process: the use of industrial whitening sprays has to be avoided, due to the physicochemical processes required to clean the surface after scanning and because the chemical properties of these sprays may damage the original object. As an alternative to them, a new way to use a common conservation material is proposed: the use of cyclododecane as a whitening spray. Thanks to its chemical stability and to the fact that it sublimes at room temperature, together with its good filmforming capabilities, a set of evaluation tests is presented to prove thatthe error introduced by the opaque thin layer created on the surface of the artifact is smaller than the accuracy of the 3D scanner and, thus, no acquisition errors are introduced. A comparison with general-purpose industrial whitening sprays is also presented, and achieved results show no significant differences in the quality of the resulting 3D models.This work is supported by the "Programa de Ayudas de Investigacion y Desarrollo (PAID)" of the Universitat Politecnica de Valencia and the "Plan Nacional de I+D+i 2008-2011" from the Ministerio de Economia y Competitividad of Spain, Projects ID: HAR2012-38391-C02-01 and HAR2012-38391-C02-02.Díaz Marín, MDC.; Aura Castro, E.; Sánchez Belenguer, C.; Vendrell Vidal, E. (2016). Cyclododecane as opcifier for digitalization of archaeological glass. Journal of Cultural Heritage. 17:131-140. https://doi.org/10.1016/j.culher.2015.06.003S1311401

A 3D deformable model-based framework for the retrieval of near-isometric flattenable objects using Bag-of-Visual-Words

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Review and comparison of Non Conventional Imaging Systems for 3D Digitization of Transparent Objects

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Developing 3D vision systems for transparent objects

International audienceNoncontact method captures UV-induced fluorescence to digitize clear objects

Optimization of transparent objects digitization from visible fluorescence UV-induced

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Novel automated methods for coarse and fine registrations of point clouds in high precision metrology

International audienceSeveral measuring systems can be combined to perform accurate assessments at the sub-micrometre level in dimensional metrology. The obtained data are fused into a common coordinate system using registration methods for which the optimal transformation parameters from the common parts of the data called correspondences are computed. New original automated coarse and fine registration methods are proposed here using discrete curvatures: an improved Hough Transformation method for the coarse registration and three Iterative Closest Points (ICP) variants for the fine registration. The enhancement of Hough consists of exploiting the curvature parameters in order to minimize the basic algorithm complexity. Thus local transformation parameters are only computed for points presenting similar precalculated surface type. While the rough alignment of the scene data and the model data is thereafter optimized through the fine registration using commonly ICP algorithm, the first ICP variant includes the curvedness and surface type similarity constraints, especially to reduce the searching area during the matching step. For the proposed second ICP variant, correspondences are searched using a specific distance criterion involving curvature features similarity measure defined from principal curvatures. The third ICP variant combines both point-to-point and point-to-plane minimizations automatically-2-weighted in the objective function, with the use of Moving Least Squares (MLS) surface technique to determine the corresponding point in point-to-point part. The three developed methods are tested on simulated and real data obtained from a computer tomography (CT) system. The results reveal the benefit of the proposed new automated coarse and fine registration approaches

Non-conventional imaging systems for 3D digitization of transparent objects: Shape from polarization in the IR and shape from visible fluorescence induced UV

International audienceThis paper presents a comparison between recent advances made in the field of non conventionnal imaging techniques for 3D digitization of transparent object. After a large survey, this paper will focus on two recent techniques later called : shape from Visible Fluorescence UV-induced and shape from polarisation in the IR which recently emerged. Results obtained with the technique of Scanning from Heating which, originaly developed in 2008 for the digitization of transparent objects, has sucessfully been modified and applied to the digitization of specular objects

Shape from polarization in the far IR applied to 3D digitization of transparent objects

International audienceThis paper presents an application of “shape from polarization” method in the far Infrared range with applications for three-dimensional reconstruction oftransparent objects. Shape from polarization is a recent application of more general polarization imaging technique having the aim to digitize the shape of the observed object. The principle is to evaluate the normal on each observed point followed by an integration procedure. The technique is well developed in the visible domain, but not in the far infrared domain due to the requirement of telecentric optics. We propose here a complete setup in the 8-13 micrometer spectral band with an appropriate source and a reconstruction method including the pinhole camera model in order to use standard optics for the camera. We present primary results of three-dimensional digitization of transparent objects