Examinando por Materia "Image analysis"
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Ítem Analysis of vibrations in a plate using interferometric methods(SPIE-INT SOC OPTICAL ENGINEERING, 2004-01-01) Rueda, E.; Angel, L.; Velasquez, D.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this work some frequencies and modes of vibration of a thin plate were determined using interferometric methods like: real-time holographic interferometry, time-average holographic interferometry, digital speckle pattern interferometry DSPI. And the results obtained are compared with those obtained with the program of finite elements COSMOS.Ítem Double exposure specklegrams obtained by using scaled aperture pupils(SPIE-INT SOC OPTICAL ENGINEERING, 2001-01-01) Angel, L; Tebaldi, M; Trivi, M; Bolognini, N; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn speckle photography the pupil aperture is usually not modified between exposures. In our work, the change of the pupil aperture scale between exposures is analysed on the basis of double-exposed image speckle, before and after a diffuser inplane displacement is done. The apertures have the same shape but its scale is modified between exposures. Note that the relative position of the aperture is maintained. In particular, we analyse a simple case that uses a circular aperture whose diameter is modified for recording each image. The intensities in the image plane and the fringe visibility are evaluated, in terms of the geometric characteristics of the pupils. © 2001 SPIE · 0277-786X/01/$15.00.Ítem EMIR: The GTC NIR multi-object imager-spectrograph(SPIE-INT SOC OPTICAL ENGINEERING, 2006-01-01) Garzón, F.; Abreu, D.; Barrera, S.; Becerril, S.; Cairós, L.M.; Díaz, J.J.; Fragoso, A.B.; Gago, F.; Grange, R.; González, C.; López, P.; Patrón, J.; Pérez, J.; Rasilla, J.L.; Redondo, P.; Restrepo, R.; Saavedra, P.; Sánchez, V.; Tenegi, F.; Vallbé, M.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaEMIR, currently entering into its fabrication and AIV phase, will be one of the first common user instruments for the GTC, the 10 meter telescope under construction by GRANTECAN at the Roque de los Muchachos Observatory (Canary Islands, Spain). EMIR is being built by a Consortium of Spanish and French institutes led by the Institute de Astrofisica de Canarias (IAC). EMIR is designed to realize one of the central goals of 10m class telescopes, allowing observers to obtain spectra for large numbers of faint sources in an time-efficient manner. EMIR is primarily designed to be operated as a MOS in the K band, but offers a wide range of observing modes, including imaging and spectroscopy, both long slit and multiobject, in the wavelength range 0.9 to 2. 5 µm. It is equipped with two innovative subsystems: a robotic reconfigurable multislit mask and disperssive elements formed by the combination of high quality difracction grating and conventional prisms, both at the heart of the instrument. The present status of development, expected performances, schedule and plans for scientific exploitation are described and discussed. The development and fabrication of EMIR is funded by GRANTECAN and the Plan Nacional de Astronomia y Astrofisica (National Plan for Astronomy and Astrophysics, Spain).Ítem Fringe visibility analysis with different scale apertures in speckle photography(TAYLOR & FRANCIS LTD, 2001-09-15) Angel, L; Tebaldi, M; Trivi, M; Bolognini, N; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe use of different scale aperture pupils for image recording in speckle photography is analysed. In particular a double-exposure specklegram is considered. The ensemble-average intensity in the Fourier plane is analytically derived and fringe visibility is investigated. The theoretical results are verified by in-plane displacement translation experiments.Ítem Properties of speckle patterns generated through multiaperture pupils(ELSEVIER SCIENCE BV, 2001-05-15) Angel, L; Tebaldi, M; Trivi, M; Bolognini, N; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe characteristics of the image speckles obtained through multiple aperture pupils are theoretically analyzed in terms of the parameters defining the pupils. The possibility of interpreting and synthesizing the image speckle distribution in terms of rather elementary structures is considered, based on the Fourier optics analysis. Then, first and second order statistical properties of the speckle patterns are studied by evaluating both the mutual intensity and the auto-correlation intensity of speckle distributions obtained by means of pupils consisting of identical apertures. Experimental results are presented to confirm the analysis. © 2001 Published by Elsevier Science B.V.Ítem Statistical tuning of adaptive-weight depth map algorithm(SPRINGER, 2011-01-01) Hoyos, Alejandro; Congote, John; Barandiaran, Inigo; Acosta, Diego; Ruiz, Oscar; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosIn depth map generation, the settings of the algorithm parameters to yield an accurate disparity estimation are usually chosen empirically or based on unplanned experiments. A systematic statistical approach including classical and exploratory data analyses on over 14000 images to measure the relative influence of the parameters allows their tuning based on the number of bad-pixels. Our approach is systematic in the sense that the heuristics used for parameter tuning are supported by formal statistical methods. The implemented methodology improves the performance of dense depth map algorithms. As a result of the statistical based tuning, the algorithm improves from 16.78% to 14.48% bad-pixels rising 7 spots as per the Middlebury Stereo Evaluation Ranking Table. The performance is measured based on the distance of the algorithm results vs. the Ground Truth by Middlebury. Future work aims to achieve the tuning by using significantly smaller data sets on fractional factorial and surface-response designs of experiments. © 2011 Springer-Verlag.