1,720,986 research outputs found
Geometry engine architecture with early backface culling hardware
No full textMost graphics accelerators waste valuable performance on transforming invisible vertices. To solve this problem, we have performed backface culling (BFC) earlier than transform and lighting (TnL). This paper proposes a survived vertex decision (SVD) algorithm to remove invisible vertices, and also suggests a geometry engine architecture that performs the early BFC with the SVD algorithm. This approach requires less hardware overhead. The SVD algorithm discards a vertex only if all triangles sharing that vertex are invisible in the mesh representing triangle lists or strips. The dedicated hardware performing the early BFC guarantees better performance in our approach, since it runs with the vertex engines in parallel. Particularly for a standalone engine, we introduce a unified architecture named the VP-Engine, which can perform the same tasks of the vertex engine and also handle the early BFC. Our architecture is designed using an instruction set simulator with a C + + library for cycle-accurate simulations. The early BFC removes half of the vertices that are transformed in the conventional approach, and as such the performance of our proposed architecture is twice as fast at maximum. Even with the sequential operations of early BFC and typical TnL, the VP-Engine is faster while the length of a vertex program is larger than 24. (c) 2005 Elsevier Ltd. All rights reserved
A method to generate soft shadows using a layered depth image and warping
No full textWe present an image-based method for propagating area light illumination through a Layered Depth Image (LDI) to generate soft shadows from opaque and nonrefractive transparent objects. In our approach, using the depth peeling technique, we render an LDI from a reference light sample on a planar light source. Light illumination of all pixels in an LDI is then determined for all the other sample points via warping, an image-based rendering technique, which approximates ray tracing in our method. We use an image-warping equation and McMillan's warp ordering algorithm to find the intersections between rays and polygons and to find the order of intersections. Experiments for opaque and nonrefractive transparent objects are presented. Results indicate our approach generates soft shadows fast and effectively. Advantages and disadvantages of the proposed method are also discussed
Head design scheme for perpendicular recording with single layered media
No full textFor ultra high areal recording density, we suggest the perpendicular recording scheme with ring head and single layered media for easy implementation. To improve the perpendicular head field and its gradient, conventional ring head is modified by cutting the top pole edge. Head field was calculated with nonlinear finite element method. The write process was simulated with micromagnetics using the calculated head field of two heads (original and modified) at each magnetic grain of recording disk, instead of using Karlqvist head field. Both simulated and measured MFM images show that the transition of modified head is clearer than original one. Also, TAA and SNR of modified head are higher than results of original head. With simple modification, currently used ring head can be easily applied to high density perpendicular recording HDD system.
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
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