1,721,030 research outputs found
3D relevance feedback via multilevel judgements
No full textRelevance feedback techniques are expected to play an important role in 3D search engines, as they help to bridge the semantic gap between the user and the system. Indeed, similarity is a cognitive process that depends on the observer.We propose a novel relevance feedback technique, which relies on the assumption that similarity may emerge from the inhibition of differences, i.e., from the lack of diversity with respect to the shape properties taken into account. To this end, a user is provided with a variety of shape descriptors, each analyzing different shape properties. Then the user expresses his/her multilevel relevance judgements, which correspond to his/her concept of similarity among the retrieved objects. Finally, the system inhibits the role of the shape properties that do not reflect the user\u27s idea of similarity. The feedback technique is based on a simple scaling procedure, which does not require neither a priori learning nor parameter optimization. We show examples and experiments on a benchmark dataset of 3D models
On converting sets of tetrahedra to combinatorial and PL manifolds
No full textWe investigate the problem of removing singularities from a non-manifold tetrahedral mesh so as to convert it to a more exploitable manifold representation. Given the twofold combinatorial and geometrical nature of a 3D simplicial complex, we propose two conversion algorithms that, depending on the targeted application, modify either its connectivity only or both its connectivity and its geometry. In the first case, the tetrahedral mesh is converted to a combinatorial 3-manifold, whereas in the second case it becomes a piecewise linear (PL) 3-manifold. For both the approaches, the conversion takes place while using only local modifications around the singularities. We outline sufficient conditions on the mesh to guarantee the feasibility of the approaches and we show how singularities can be both identified and removed according to the configuration of their neighborhoods. Furthermore, besides adapting and extending surface-based approaches to a specific class of full-dimensional simplicial complexes in 3D, we show that our algorithms can be implemented using a flexible data structure for manifold tetrahedral meshes which is suitable for general applications. In order to exclude pathological configurations while providing sound guarantees, the input mesh is required to be a sub-complex of a combinatorial ball; this makes it possible to assume that all the singularities are part of the mesh boundary
Multilevel relevance feedback for 3D shape retrieval
No full textRelevance feedback techniques are expected to play an important role in 3D search engines, as they help to bridge the semantic gap between the user and the system: similarity is a cognitive process, depending on the observer. We propose a novel relevance feedback technique, whose basic idea is threefold. First of all, the user is provided with a variety of shape descriptors, analysing different shape properties. The user then expresses her similarity concept through a friendly interface which supports multilevel relevance judgements. Finally, the system inhibits the role of the shape properties that do not reflect the user\u27s idea of similarity. The assumption is that similarity may emerge as an inhibition of differences, i.e., as a lack of diversity with respect to the shape properties taken into account. The proposed technique is based on a simple scaling procedure, which does not require any a priori learning or optimization of parameters
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
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