1,720,973 research outputs found
Toward wide-area camera localization for mixed reality
No full textThis paper describes a work in progress towards the implementation of a complete system that provides tourists with relevant visual information related to cultural heritage sites. Thanks to the diffusion of high-end mobile devices and the recent improvement in computer vision research on 3D Structure and Motion reconstruction, it is now possible to develop mobile mixed reality applications that can interact with spots of historical interest in the city. In particular we present an accurate localization of the mobile device that leverages on a pre-computed 3D structure to obtain image-model correspondences. Preliminary experiments with a calibrated camera – indoor and outdoor – demonstrate sufficient accuracy to support mixed reality
Combined use of ToF sensors and standard cameras for 3D video acquisition
No full text3D video applications usually require the availability of
high resolution depth and color information. Depth information
can be acquired at video rate by Time-of-Flight matrix
sensors, but these devices usually have a limited resolution
and image quality. A common solution to this issue is the
combined use of ToF sensors and color cameras. This paper
firstly presents a generalized multi-camera calibration technique
that aims at calibrating together the ToF sensor with
two synchronized cameras exploiting the color information
from both type of sensors but also the depth measures of the
ToF sensor. In the second part of the work we will present an
ad-hoc interpolation technique to obtain high resolution depth
information exploiting side information from the color camera
together with the ToF measures and a novel surface prediction
scheme. Finally we will show how the high resolution
depth map obtained with the proposed approach can be used
in order to warp the available video streams to arbitrary viewpoints
in 3D video applications. Experimental results have
shown how the proposed method allows to obtain a more accurate
calibration and to improve the quality of the depth data
and warped views if compared with standard approaches
A Novel Interpolation Scheme for Range Data with Side Information
Full text linkTime-of-Flight matrix sensors currently available allow for the acquisition of range maps at video rate but usually have a limited resolution. At the same time high resolution color cameras are widely available. This makes highly desirable methods that are able to exploit the combined use of ToF sensors and color cameras to obtain high resolution range maps. This work presents a novel interpolation technique that exploits side information from a standard color camera to increase the resolution of range maps. A segmented version of the high resolution color image is used in order to identify the main objects in the scene, while a novel surface prediction scheme is used to interpolate the available depth samples. Critical issues like the joint calibration of the two devices and the unreliability of the acquired data have also been taken into account with ad- hoc solutions. The performance of the proposed scheme has been verified with both synthetic and real-world data and experimental results have shown how the proposed method allows to obtain a more accurate interpolation with sharper edges if compared with standard approaches
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Solving the PnP Problem with Anisotropic Orthogonal Procrustes Analysis.
Full text linkIn this paper we formulate the Perspective-n-Point (a.k.a. exterior orientation) problem in terms of an instance of the anisotropic orthogonal Procrustes problem, and de- rive its solution. Experiments with synthetic and real data demonstrate that our method reaches the best trade-off be- tween speed and accuracy. The MATLAB code reported in the paper testifies that it is also exceedingly simple to im- plement
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