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A method for computing the visible regions of free-form surfaces is proposed in this paper. Our work is focused on accurately
calculating the visible regions of the sequenced rational Bézier surfaces forming a solid model and having coincident edges
but no inner-intersection among them. The proposed method calculates the silhouettes of the surfaces without tessellating
them into triangle meshes commonly used in previous methods so that arbitrary precision can be obtained. The computed silhouettes
of visible surfaces are projected onto a plane orthogonal to the parallel light. Then their spatial relationship is applied
to calculate the boundaries of mutual-occlusion regions. As the connectivity of the surfaces on the solid model is taken into
account, a surface clustering technique is also employed and the mutual-occlusion calculation is accelerated. Experimental
results showed that our method is efficient and robust, and can also handle complex shapes with arbitrary precision.
Project supported by the National Basic Research Program (973) of China (No. 2002CB312106) and the National Natural Science
Foundation of China (Nos. 60533070, and 60403047). The third author was supported by the project sponsored by a Foundation
for the Author of National Excellent Doctoral Dissertation of China (No. 200342) and a Program for New Century Excellent Talents
in University (No. NCET-04-0088), China 相似文献
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文章从单色光强的计算出发,探讨了光源的线度对干涉条纹可见度的影响。并以杨氏双缝干涉为例做定量分析,计算出了光源的临界宽度。 相似文献
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Automatic web image annotation is a practical and effective way for both web image retrieval and image understanding. However, current annotation techniques make no further investigation of the statement-level syntactic correlation among the annotated words, therefore making it very difficult to render natural language interpretation for images such as ＂pandas eat bamboo＂. In this paper, we propose an approach to interpret image semantics through mining the visible and textual information hidden in images. This approach mainly consists of two parts： first the annotated words of target images are ranked according to two factors, namely the visual correlation and the pairwise co-occurrence; then the statement-level syntactic correlation among annotated words is explored and natural language interpretation for the target image is obtained. Experiments conducted on real-world web images show the effectiveness of the proposed approach. 相似文献
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Jamie Skerski 《传播与批判/文化研究》2013,10(4):363-381
Ellen DeGeneres was celebrated. She was chastised. And then she was cancelled. Her current success makes it easy to forget how short-lived her lesbianism initially lasted on television (less than two years). Ironically, in the aftermath of Ellen's, demise we witnessed a profound increase in queer characters, themes, and programming as well as her own spectacular comeback. Moving beyond most academic consideration of Ellen DeGeneres’ initial emergence as lesbian celebrity, I highlight the cancellation of her sitcom as a particularly crucial moment for understanding the fierce multilayered disciplining of Ellen's public persona. Further, I consider the disparate discourses and entertainment journalism that articulated a public/private DeGeneres with her television character(s), working to shape her public persona in the interest of preserving prevailing cultural norms. 相似文献
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马太效应对于科学成果的能见度的作用和影响是深刻而广泛的。文章以中国科学技术信息研究所自行研制的“中国高层次科技人才信息数据库”为基础,分析了材料领域获得国家级奖励的高层次科技人才中,马太效应对其科研成果能见度的影响,得到结论：首先,马太效应对于科学成果的能见度具有普遍性;其次,马太效应对于科学成果能见度的影响存在一个由高峰逐渐衰减的周期过程;最后,马太效应存在两面性,对于科学成果的能见度既有积极作用,又存在消极作用。 相似文献
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Armando Menéndez-Viso 《Ethics and Information Technology》2009,11(2):155-162
Transparency has evolved from an individual, dangerous power in Plato to a desirable, collective property in the contemporary world. This paper intends to give a brief account of this long and somehow surprising path and extract some interesting consequences for economic and political activities, as well as for information technologies. Six literary masterpieces are used to highlight the contradictions and dangers entailed by the abuse of the fascinating metaphor of transparency. In the end, what is usually intended when demanding transparency from a corporation, a firm or a state is more (or more accessible) information about it, i.e., understandable and abundant black and white data. This means reporting, picturing, producing material, becoming apparent, which is precisely the contrary of being transparent. We don’t want to look through, but to look directly at. The question, then, is not transparency, but opacity: what do we need and want to see, and how is this going to be produced? 相似文献
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为了解长江三角洲地区能见度区域状况,选取嘉兴市作为代表站点进行气象和大气污染物的同步监测分析能见度的,特征和影响因素。结果表明：晴天时能见度随相对湿度和PM2．5的变化而变化的规律很明显,雨天时能见度变化复杂。能见度与污染因子的相关性受气象因子影响很大,当控制风速时,就会减小污染因子对能见度的贡献,气象因子和能见度的相关性很复杂,不同因子作用下,气象因子对能见度的贡献不同。 相似文献
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This essay demonstrates how visual works of art may operate rhetorically to articulate public knowledge, to illustrate the moral challenges facing citizens, and to shape commemorative practices, through an analysis of Norman Rockwell's civil rights paintings of the 1960s. By examining the rhetorical aspects of these paintings, including their form and composition, the essay demonstrates the power of visual works of art to evoke common humanity in three significant ways: (1) disregarding established caricatures; (2) creating recognition of others through particularity; and (3) depicting material aspects of American society, thereby reminding viewers that abstract political concepts are always relative to the individuals or groups whose lives are most directly influenced by their presence or absence. 相似文献