Direct Differential Photometric Stereo Shape Recovery of Diffuse and Specular Surfaces

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s10851-016-0633-0Recovering the 3D shape of an object from shading is a challenging problem due to the complexity of modeling light propagation and surface reflections. Photometric Stereo (PS) is broadly considered a suitable approach for high-resolution shape recovery, but its functionality is restricted to a limited set of object surfaces and controlled lighting setup. In particular, PS models generally consider reflection from objects as purely diffuse, with specularities being regarded as a nuisance that breaks down shape reconstruction. This is a serious drawback for implementing PS approaches, since most common materials have prominent specular components. In this paper, we propose a PS model that solves the problem for both diffuse and specular components aimed at shape recovery of generic objects with the approach being independent of the albedo values thanks to the image ratio formulation used. Notably, we show that by including specularities, it is possible to solve the PS problem for a minimal number of three images using a setup with three calibrated lights and a standard industrial camera. Even if an initial separation of diffuse and specular components is still required for each input image, experimental results on synthetic and real objects demonstrate the feasibility of our approach for shape reconstruction of complex geometries.The first author acknowledges the support of INDAM under the GNCS research Project “Metodi numerici per la regolarizzazione nella ricostruzione feature-preserving di dati.

Creació d’unitats formatives i la seva programació per al mòdul de Pedra Natural

En el centre on es van realitzar les pràctiques es va estar, bàsicament, amb alumnes que cursaven el Cicle Formatiu de Grau Mitjà (CFGM) d’Obres de la Construcció de la família d’Edificació i Obra Civil. Aquest Cicle Formatiu durant aquest curs 2011/2012 s’ha impartit en el format que marca la Llei Orgànica General del Sistema Educatiu de 3 d’octubre del 1990 (LOGSE). Malgrat això, l’any vinent s’haurà d’impartir segons les pautes que marca la nova llei d’educació, la Llei Orgànica de l’Educació del 3 de maig del 2006 (LOE). Amb les Hores de Lliure Disposició dels centres docents (HLLD) que marca la normativa, el centre, quan va començar a impartir aquest cicle formatiu, va decidir invertir-les en la creació d’un nou crèdit: el crèdit de Pedra Natural. Un crèdit únic, que només s’imparteix en aquest centre docent. Amb el canvi de normativa, aquest també és objecte de canvis, i aquests són l’objectiu principal d’aquest Treball Final de Màster (TFM), l'adaptació d’aquest crèdit a un nou mòdul. Per tant, s’ha fet la programació del nou mòdul de Pedra Natural i el disseny del seu currículum, com la creació de 3 noves Unitats Formatives (UF), amb els seus Resultats d’Aprenentatge (RA), Criteris d’Avaluació (CA) i Continguts (C). S’ha aprofitat també per introduir en el currículum continguts d’especial interès en la actualitat, com la rehabilitació o el disseny. Finalment, s’han dissenyat les Activitats d’Ensenyament – Aprenentatge d’un Nucli Formatiu (NF). Per al disseny d’aquestes activitats s’ha fet servir un mètode d’innovació docent, el mètode del puzle de Aronson. Mètode el qual treballa el constructivisme i l’aprenentatge cooperatiu. Dins d’aquestes activitats s’hi ha englobat una sortida al Museu de Geologia Valentí Masachs de la Escola Politècnica Superior d’Enginyeria de Manresa (EPSEM) de la Universitat Politècnica de Catalunya (UPC)

Volumetric Lissajous confocal microscopy with tunable spatiotemporal resolution

Dynamic biological systems present challenges to existing three-dimensional (3D) optical microscopes because of their continuous temporal and spatial changes. Most techniques are rigid in adapting the acquisition parameters over time, as in confocal microscopy, where a laser beam is sequentially scanned at a predefined spatial sampling rate and pixel dwell time. Such lack of tunability forces a user to provide scan parameters, which may not be optimal, based on the best assumption before an acquisition starts. Here, we developed volumetric Lissajous confocal microscopy to achieve unsurpassed 3D scanning speed with a tunable sampling rate. The system combines an acoustic liquid lens for continuous axial focus translation with a resonant scanning mirror. Accordingly, the excitation beam follows a dynamic Lissajous trajectory enabling sub-millisecond acquisitions of image series containing 3D information at a sub-Nyquist sampling rate. By temporal accumulation and/or advanced interpolation algorithms, the volumetric imaging rate is selectable using a post-processing step at the desired spatiotemporal resolution for events of interest. We demonstrate multicolor and calcium imaging over volumes of tens of cubic microns with 3D acquisition speeds of 30 Hz and frame rates up to 5 kHz

Time-resolved imaging of the laser forward transfer of liquids

Time-resolved imaging is carried out to study the dynamics of the laser-induced forward transfer of an aqueous solution at different laser fluences. The transfer mechanisms are elucidated, and directly correlated with the material deposited at the analyzed irradiation conditions. It is found that there exists a fluence range in which regular and well-defined droplets are deposited. In this case, laser pulse energy absorption results in the formation of a plasma, which expansion originates a cavitation bubble in the liquid. After the further expansion and collapse of the bubble, a long and uniform jet is developed, which advances at a constant velocity until it reaches the receptor substrate. On the other hand, for lower fluences no material is deposited. In this case, although a jet can be also generated, it recoils before reaching the substrate. For higher fluences, splashing is observed on the receptor substrate due to the bursting of the cavitation bubble. Finally, a discussion of the possible mechanisms which lead to such singular dynamics is also provided

Sub-wavelength laser nanopatterning using droplet lenses

When a drop of liquid falls onto a screen, e.g. a cell phone, the pixels lying underneath appear magnified. This lensing effect is a combination of the curvature and refractive index of the liquid droplet. Here, the spontaneous formation of such lenses is exploited to overcome the diffraction limit of a conventional laser direct-writing system. In particular, micro-droplets are first laser-printed at user-defined locations on a surface and they are later used as lenses to focus the same laser beam. Under conditions described herein, nanopatterns can be obtained with a reduction in spot size primarily limited by the refractive index of the liquid. This all-optics approach is demonstrated by writing arbitrary patterns with a feature size around 280 nm, about one fourth of the processing wavelength

Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia

Manufacturing of glass from tin mining tailings in Bolivia Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua,Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626º to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals

Permian-Triassic red-stained albitized profiles in the granitic basement of the NE Spain: evidence for deep alteration related to the Triassic Palaeosurface

Extensive areas of the Variscan granitic basement in NE Spain display profiles of red-stained albitized facies characterized by albitization of Ca-plagioclase, chloritization of biotite and microclinization of orthoclase, along with the alteration of igneous quartz to secondary CL-dark quartz. These profiles have a geopetal structure beneath the Triassic unconformity, with a very intense and pervasive alteration in the upper part that progressively decreases with depth to 150-200 m where the alteration is restricted to the walls of fractures. The red albitized facies contains secondary maghemite and hematite that indicate oxidizing conditions. Dating of microclinized orthoclase and secondary monazite that have formed in the red-stained albitized facies yielded K-Ar and U-Th-Pbtotal ages of 240 and 250 Ma, respectively, suggesting that the alteration developed during the Permian-Triassic period. The geopetal disposition of the red albitized profile with respect to the Triassic unconformity, its large regional extent, and the fracture-controlled alteration in the lower part of the profile indicate groundwater interaction. The δ18O values of albitized plagioclase (+ 11¿), microclinized orthoclase (+ 13¿), and secondary CL-dark quartz (+ 12¿) suggest that the alteration temperature was about 55 °C. This 'low' temperature suggests that the alteration occurred during interaction of the granitic rocks with Na-rich fluids below a surficial weathering mantle on the Permian-Triassic palaeosurface. The latter is possibly related to Triassic evaporitic environments in long-lasting, stable landscapes in which Na-rich solutions infiltrated deep regional groundwaters

L'estudi del museu de geologia d'Oruro (Bolívia)

Bolívia compta amb una de les majors riqueses mineralògiques del món (Hyršl i Petrov, 2009). Una bona representació d’elles es troba al Museo Mineralógico de la Facultad de Minas de la UTO en Oruro (Llanque, 2006; Neumeier, 2009; Petrov, 2009). La trajectòria de més de cent anys de la col∙lecció però, havia provocat que aquesta no presentavà la seva millor situació. És per això que es decideix dur a terme una catalogació, inventariat i reordenació de les mostres mineralògiques de què disposa. Per fer-ho s'utilitzen diverses tècniques d'identificació mineral, que van des de les clàssiques de visu fins a mètodes més sofisticats com l'estudi petrogràfic amb làmina prima o amb Difracció de RX. Es procedeix també a la renovació de les fitxes identificatòries i al fotografiat de les més de 3500 mostres. Amb aquesta finalitat se signa el projecte de col∙laboració entre la Universitat Politècnica de Catalunya (U.P.C.) i la Universidad Técnica de Oruro (U.T.O.), en què es busca una sol∙lució als problemes mencionats durant l’any 2010.Peer Reviewe