1,720,956 research outputs found
Tracking human motion with multiple cameras using articulated ICP with hard constraints
Get PDFQuesta tesi propone un nuovo algoritmo basato su ICP per il tracking di un modello
scheletrico articolato di un corpo umano. L’algoritmo proposto prende in input immagini
calibrate di un soggetto, calcola la ricostruzione volumetrica e la linea mediale del corpo
e quindi posiziona in modo adeguato il modello, composto di segmenti, in ogni frame
usando una versione di ICP modificata (versione che usa una strategia di attraversamento
alberi gerarchica che mantiene connessi tutti i segmenti del modello nei giunti relativi).
L’approccio proposto usa limiti cinematica per i giunti e un filtro di Kalman esteso per
fare il tracking del modello.
Il primo contributo originale di questa tesi è l’algoritmo per trovare i punti sullo scheletro
di un volume tridimensionale. L’algoritmo, usando una tecnica di slicing trova l’asse
mediale di un volume 3D in modo veloce utilizzando il processore della scheda grafica e
le texture units della scheda stessa. Questo algoritmo produce ottimi risultati per quanto
riguarda la qualità e le prestazioni se comparato con altri algoritmi in letteratura.
Un altro contributo originale è l’introduzione di una nuova strategia di tracking basata su
un approccio gerarchico dell’algoritmo ICP, utilizzato per trovare le congruenze tra un
modello di corpo umano composto da soli segmenti e un insieme di punti 3D.
L’algoritmo usa una versione di ICP dove tutti i punti 3D sono pesati in funzione del
segmento del corpo preso in considerazione dall’algoritmo in quel momento.
L’applicazione di queste tecniche dimostra la bontà del metodo e le prestazioni ottenute
in termini di qualità della stima della posa sono comparabili con altri lavori in letteratura.
I risultati presentati nella tesi dimostrano la fattibilità dell’approccio generale, che si
intende utilizzare in un sistema completo per il tracking di corpi umani senza l’uso di
marcatori. In futuro il lavoro può essere esteso ottimizzando l’implementazione e la
codifica in modo da poter ottenere prestazioni real-time.This thesis proposed a new ICP-based algorithm for tracking articulated skeletal model of
a human body. The proposed algorithm takes as input multiple calibrated views of the
subject, computes a volumetric reconstruction and the centerlines of the body and fits the
skeletal body model in each frame using a hierarchic tree traversal version of the ICP
algorithm that preserves the connection of the segments at the joints. The proposed
approach uses the kinematic constraints and an Extended Kalman Filter to track the body
pose.
The first contribution is a new algorithm to find the skeletal points of a 3D volume. The
algorithm using a slicing technique find the medial axis of a volume in a fast way using
the graphic card processor and the texture units. This algorithm produce good results in
quality and performance compared to other works in literature.
Another contribution is the introduction of a new tracking strategy based on a
hierarchical application of the ICP standard algorithm to find the match between a stick
body model and a set of 3D points. The algorithm use a traversing version of ICP where
also all the 3D points are weighted in such a way every limbs of the model can best fit on
the right portion of the body.
The application of these techniques shown the feasibility of the method and the
performances obtained in terms of quality of estimate pose are comparable
with other works in literature.
The results presented here demonstrate the feasibility of the approach, which is is
intended to be used in complete system for vision-based markerless human body
tracking. Future work will aimed at optimizing the implementation, in order to achieve
real-time performances
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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