1,721,004 research outputs found
Spectral Synchronization of Multiple Views in SE(3)
Full text linkThis paper addresses the problem of rigid-motion synchronization (a.k.a. motion averaging) in the Special Euclidean Group SE(3), which finds application in structure-from-motion and registration of multiple three-dimensional (3D) point-sets. After relaxing the geometric constraints of rigid motions, we derive a simple closed-form solution based on a spectral decomposition, which is then projected onto SE(3). Our formulation is extremely efficient, as rigid-motion synchronization is cast to an eigenvalue decomposition problem. Robustness to outliers is gained through Iteratively Reweighted Least Squares. Besides providing a theoretically appealing solution, since our method recovers at the same time both rotations and translations, we demonstrate through experimental results that our approach is significantly faster than the state of the art, while providing accurate estimates of rigid motions
Geografia attiva con la cartografia: una proposta
No full textIl contributo è finalizzato a far acquisire la “carta mentale” di un determinata area in modo operativo, e anche piacevole, soprattutto a studenti della Secondaria di primo grado. Dopo l’esposizione della tecnica dello “smontaggio” della carta geografica su idonei foglietti di carta da lucido, si cerca di favorire la riflessione degli studenti sulle ubicazione delle varie componenti territoriali disegnate e impresse nella mente, senza particolare sforzo mnemonico. Da questa geografia “descrittiva”, è necessario far sperimentare allo studente, con la sovrapposizione dei lucidi e l’uso delle carte tematiche dell’atlante, che è possibile realizzare una geografia “interpretativa”, convalidata dal libro di testo, usato come prima “fonte” e risposta immediata a quesiti e richieste.“EXPERIMENT” GEOGRAPHY: A PROPOSAL. The contribution aims at making secondary school students acquire the "mental map" of a specific area in a practical and pleasant way. After exposing the geographic map "dismantling" technique on suitable sheets of tracing paper, we try to encourage students to reflection on the spatial location of various territorial components, previously drawn and fixed in their mind without any special memory effort. From this "descriptive" geography, it is important to make the student experiment, by superimposing tracing paper sheets and using atlas thematic maps, that it is possible to create "interpretative" geography, confirmed by their textbook, which is used as the first "source" for any question or doubt
Tra due mondi (o in un mondo nuovo?)
No full textL'articolo esamina i problemi degli immigrati di seconda generazione che frequentano le scuole italiane, dal bilinguismo alla mediazione tra due sistemi culturali differenti e spesso contrastanti. Si tratta di una trattazione di geografia culturale e di geografia delle lingue, con particolare attenzione al fenomeno migratorio. Caso di studio è una studentessa marocchina iscritta alla secondaria di secondo grado
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
Robust synchronization in SO(3) and SE(3) via low-rank and sparse matrix decomposition
Full text linkThis paper deals with the synchronization problem, which arises in multiple 3D point-set registration and in structure-from-motion. The problem is formulated as a low-rank and sparse matrix decom- position that caters for missing data, outliers and noise, and it benefits from a wealth of available decomposition algorithms that can be plugged-in. A minimization strategy, dubbed R-GoDec, is also proposed. Experimental results on simulated and real data show that this approach offers a good trade-off between resistance to outliers and speed
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
Camera Motion from Group Synchronization
No full textThis paper deals with the problem of estimating camera motion in the context of structure-from-motion. We describe a pipeline that consumes relative orientations and produces absolute orientations (i.e. camera position and attitude in an absolute reference frame). This pipeline exploits the concept of 'group synchronization' in most of its stages, all of which entail direct solutions such as eigenvalue decompositions or linear least squares. A comprehensive introduction to the group synchronization problem is provided, and the proposed pipeline is evaluated on standard real datasets
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
- …
