1,720,966 research outputs found
Path tracing in Production: The Path of Water
No full textPhysically-based light transport simulation has become a widely established standard to generate images in the movie industry. It promises various important practical advantages such as robustness, lighting consistency, progressive rendering and scalability. Through careful scene modelling it allows highly realistic and compelling digital versions of natural phenomena to be rendered very faithfully. The previous Path Tracing in Production courses have documented some of the evolution and challenges along the journey of adopting this technology, yet even modern production path-Tracers remain prone to costly rendering times in various classes of scenes, of which water shots remain among those most notoriously demanding. While this series in the past years covered a wide range of different topics within one course, this year we took the unusual step to focus on just one, the water-related challenges that we encountered during our work on Avatar: The Way of Water. Despite its seemingly simple nature, water causes a very multifaceted range of issues: specular surfaces cause spiky and sparse radiance distribution at various scales and in different forms, such as underwater caustics, godrays as well as fast-moving highlights and complex indirect on FX elements such as splashes, droplets and aeration bubbles. The purpose of this course is to share knowledge and experiences on the current state of the technology to stimulate active exchange in the academic and industrial research community that will advance the field on some of the challenging industrial benchmark problems. We will first give an overview of the nature of the singularities and its practical implications and then dive deeper into appearance and material aspects of water and the objects it interacts with. In the remaining sections, the course will focus on some specific aspects in more technical detail, providing both a solid mathematical background as well as practical strategies. Furthermore, we discuss some of the remaining unsolved problems that hopefully will inspire future research
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
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
On variational problems and gradient flows in image
No full textThis thesis treats different methods and theoretical aspects of the calculus of variations and their applications in image processing, especially those in which gradient flows for the minimization of the variational problems are used. The focus lies on geometrical methods for image registration, as well as numerical methods for computing the solution for an implicit variant of Willmore flow (level set method). The problem of image registration aims at finding a suitable correspondence map by means of a deformation of one image domain to the other, such that significant structures are overlaid correctly. In practical applications, these images are often aquired by different sensors and hence yield different image modalities.
Image registration plays an important role in the clinical evaluation of medical data as for example from computed tomography or magnetic resonance imaging, as well as diagnosis and surgery planning. The proposed method aims at an alignment of geometrical descriptors instead of merely comparing image intensities. In particular, the approach is morphological (contrast invariant).
Registration methods are in general ill-posed inverse problems, hence regularization methods are necessary. In order to ensure a robust and stable minimization process, three complementary regularization strategies are incorporated and linked to each other, namely multiscale methods, Tikhonov-regularization and regularized gradient flows. The latter are based on the definition of a regularizing metric, that is used to define the representation of the regularized gradient of the energy functional. Furthermore, a nonlinear polyconvex and hyperelastic energy functional that takes the role of the Tikhonov-regularization functional allows to devise an existence proof of the geometric registration approach.
The theoretical justification of the multiscale approach is given by the study of the variational convergence of the regularized functionals by means of Gamma-convergence. In order to further stabilize the registration process, a new Mumford-Shah-based method to align significant edges is proposed. It aims the simultaneous process of registration, segmentation (feature detection) and image restoration, since these processes typically interdepend on each other.
Here, two different approaches are proposed, numerically incorporated and compared: a phase-field approach, that is based on the Ambrosio-Tortorelli approximation of the Mumford-Shah functional and a corresponding level set approach. The minimization of the Willmore functional via a semi-implicit numerical scheme is
applied to the recontruction of destroyed regions of surfaces that are given by a level set representation. The introduction of an implicit narrow band method allows a significant acceleration of the geometrical evolution
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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