Search results for "Projection"
showing 10 items of 378 documents
Projection of speckle patterns for 3D sensing
2008
In this communication we present the use of projected speckle patterns coming from a phase random mask for sensing depths and thicknesses. The sensing is based on the change of the speckle pattern with propagation and the lack of correlation between speckle patterns recorded at different depths or lateral locations. The principle is used for mapping thickness of transparent media, for depth ranging and for 3D mapping of diffuse objects.
Projection-based improvement of 3D reconstructions from motion-impaired dental cone beam CT data.
2019
Purpose Computed tomography (CT) and, in particular, cone beam CT (CBCT) have been increasingly used as a diagnostic tool in recent years. Patient motion during acquisition is common in CBCT due to long scan times. This results in degraded image quality and may potentially increase the number of retakes. Our aim was to develop a marker-free iterative motion correction algorithm that works on the projection images and is suitable for local tomography. Methods We present an iterative motion correction algorithm that allows the patient's motion to be detected and taken into account during reconstruction. The core of our method is a fast GPU-accelerated three-dimensional reconstruction algorith…
Oil prices and inflation dynamics: Evidence from advanced and developing economies
2018
Abstract We study the impact of fluctuations in global oil prices on domestic inflation using an unbalanced panel of 72 advanced and developing economies over the period from 1970 to 2015. We find that a 10% increase in global oil inflation increases, on average, domestic inflation by about 0.4 percentage points on impact, with the effect vanishing after two years and being similar between advanced and developing economies. We also find that the effect is asymmetric, with positive oil price shocks having a larger effect than negative ones. The impact of oil price shocks, however, has declined over time due in large part to a more credible monetary policy and less reliance on energy imports.…
Efficiency in constrained continuous location
1998
Abstract We present a geometrical characterization of the efficient, weakly efficient and strictly efficient points for multi-objective location problems in presence of convex constraints and when distances are measured by an arbitrary norm. These results, established for a compact set of demand points, generalize similar characterizations previously obtained for uncontrained problems. They are used to show that, in planar problems, the set of constrained weakly efficient points always coincides with the closest projection of the set of unconstrained weakly efficient points onto the feasible set. This projection property which are known previously only for strictly convex norms, allows to e…
Towards 3D Television Through Fusion of Kinect and Integral-Imaging Concepts
2015
We report a new procedure for the capture and processing of light proceeding from 3D scenes of some cubic meters in size. Specifically we demonstrate that with the information provided by a kinect device it is possible to generate an array of microimages ready for their projection onto an integral-imaging monitor. We illustrate our proposal with some imaging experiment in which the final result are 3D images displayed with full parallax.
Digital slicing of 3D scenes by Fourier filtering of integral images
2008
We present a novel technique to extract depth information from 3D scenes recorded using an Integral Imaging system. The technique exploits the periodic structure of the recorded integral image to implement a Fourier-domain filtering algorithm. A proper projection of the filtered integral image permits reconstruction of different planes that constitute the 3D scene. The main feature of our method is that the Fourier-domain filtering allows the reduction of out-of-focus information, providing the InI system with real optical sectioning capacity.
Elemental images for integral-imaging display
2013
One of the differences between the near-field integral imaging (NInI) and the far-field integral imaging (FInI), is the ratio between number of elemental images and number of pixels per elemental image. While in NInI the 3D information is codified in a small number of elemental images (with many pixels each), in FInI the information is codified in many elemental images (with only a few pixels each). The later codification is similar that the one needed for projecting the InI field onto a pixelated display when aimed to build an InI monitor. For this reason, the FInI cameras are specially adapted for capturing the InI field with display purposes. In this contribution we research the relation…
3D Integral Microscopy based in far-field detection
2018
Lately, Integral-Imaging systems have shown very promising capabilities of capturing the 3D structure of micro- scopic and macroscopic scenes. The aim of this work is to provide an optimal design for 3D-integral microscopy with extended depth of field and enhanced lateral resolution. By placing an array of microlenses at the aperture stop of the objective, this setup provides a set of orthographic views of the 3D sample. Adopting well known integral imaging reconstruction algorithms it can be shown that the depth of field as well as spatial resolution are improved with respect to conventional integral microscopy imaging. Our claims are supported on theoretical basis and experimental images …
Computation of microimages for plenoptic display
2014
We report a new algorithm for the generation of the microimages ready for their projection into an integral imaging monitor. The algorithm is based in the transformation properties of the plenoptic field captured with an array of digital cameras. We show that a small number of cameras can produce the microimages for displaying 3D scenes with resolution and parallax fully adapted to the monitor features.
Pas de titre
2011
A number of phonetic and phonological changes have lately been observed in most geographical varieties of British English. This phenomenon seems to have been accelerated by increasing social and geographical mobility in the past decades. Based on a corpus mainly consisting of several hours of spontaneous interaction between a number of native NW Yorkshire speakers divided into different age groups, this research identifies and analyses several segmental and suprasegmental innovations observed in apparent time in a set of accents associated with a circumscribed geographical area. This thesis discusses the motivation behind some of these changes and addresses the question of whether the same …