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1.
静态视点图像由于起点坐标和视线方向出现视觉偏移,在三维视景仿真中图像平滑过渡效果不好。传统方法中采用基于光线Ray光线程基元算法,光亮度产生像素色差干扰,视景仿真效果欠佳,提出一种基于归一化线性滤波的改进的Ray光线程基元算法,通过图像的每个像素沿着固定的方向虚拟构建一条发射光线,获取Ray光线程基元,采用归一化线性滤波处理,优化光线强度的衰减,修正起点坐标和视线方向出现的视觉偏移,实现静态视点的平滑过渡,仿真实验得到位置静态视点、角度静态视点和相对距离静态视点模型下的大型运动舰船视景仿真结果,仿真表明,采用该算法对静态视点的复杂图像进行三维视景仿真,能在操作进程和虚拟数据资源配置中实现并行处理,静态视点的纹理的寻址和遍历均匀,实现了平滑过渡,有较高的配准率,视景仿真效果真实可靠。 相似文献
2.
《科技通报》2015,(8)
三维虚拟成像通过对场景的动态模拟和优质的图像处理,从而给人强烈的视觉上的冲击。传统的三维成像技术采用纹理映射技术,当纹理特征受到不均匀光线干扰时,成像效果不好。提出一种基于光线滤波平滑处理的三维成像技术,结合静态视点图像的运动方程,计算视点控制视觉切换偏角,按内插点的分布范围,可以将内插分为整体内插、分块内插和逐点内插,提高三维成像的立体型,实现了三维成像的特征提取预处理。将一个归一化的灰度图像通过矩估计测得二值图中的图像面积,三维模型通过多层网格面来表示,使得三维实体模型成为一个连续的整体,生成多层网络面,通过光线滤波平滑处理,当纹理特征受到不均匀光线干扰时,仍然保持较好的成像效果。仿真结果表明,算法能通过图像分割,实现图像特征提取,并实现光线滤波平滑处理,进行三维成像,成像误差较小,三维成像的测量值逼近理论值,性能优越。 相似文献
3.
《科技通报》2016,(3)
对三维草地进行视景仿真,实时绘制随机风场作用下的草体元素,提高草地模拟的真实感。由于三维草地视景中的草体实体数量巨大,随着风场的作用发生随机的形态变化,传统方法难以有效实现对草地视景仿真。提出一种基于四方连续纹理生成的随机风场作用下的三维草地视景仿真方法。采用层状纹理方法进行三维草地场景生成再现,在随机风场作用下,采用轮廓点标记方法进行三维草地的特征分类,采用直方图算法进行模板距离度量,对三维草地在风场作用下的关键帧和当前帧进行模板匹配,对草地的等效直方图、轮廓区域中心位置、草地的镜面反射光强度、灰度极值四个属性进行归一化处理,实现四方连续纹理生成,提高风场作用下的视景仿真真实度。仿真结果表明,采用该算法进行随机风场作用下三维草地视景仿真,草体摆动效果真实性较好,动态模拟效果较好,草体目标位置的中心误差比传统方法降低,性能优越。 相似文献
4.
在三维模型视景仿真建模中,常因视觉切换和光线强度衰减,产生轮廓块间混淆,需要进行混淆分离算法设计。提出一种基于二阶累积泰勒展开的三维模型轮廓块间混淆分离方法,进行高精度多轮廓三维立体模型视景建模,对于遍历后的建模点进行模型重构,实现三维多轮廓立体模型建模。构建多轮廓三维模型视景建模视点切换运动方程,得到边缘轮廓特征检测结果。提取轮廓块间的混淆像素值二阶累积量特征,采用二阶累积量泰勒展开算法,对三维图像模型的轮廓边缘块间混淆进行分离的改进。仿真结果表明,采用该算法,混淆分离效果较好,三维图像模型的视景仿真效果真实度较高,轮廓信息保真度好,展示了算法的优越性能。 相似文献
5.
在计算机辅助三维桥梁重构和桥梁目标识别中,桥梁图像曲线曲面的形状平滑处理是关键。传统方法采用Bézier曲线曲面的自然生成方法,算法没有提升桥梁曲面多项式生成的次数,所以计算复杂度较大,三维平滑效果不佳。提出一种基于曲线端点插值平面起控的三维桥梁航拍图像HC-Bézi-er生成方法实现,对航拍图像识别。定义具有凸包性、对称性等基本性质的新曲线,对三维桥梁平面曲线端点进行控制边重合插值,组合曲线的各曲线段,构造了含积分递推多项式的平面起控基函数,实现三维桥梁图像曲线曲面的精确平滑处理和三维重构模拟。仿真实验表明,采用该算法进行三维桥梁图像模拟,桥梁曲线和曲面可以由不同数量的轮廓点控制,具有形状可调性,实现高阶的光滑拼接,信息分析准确,信息含有量饱满,实现准确三维重构,基于重构图像对航拍桥梁图像检测点的准确识别率较传统方法提高明显。 相似文献
6.
冶金过程中的温度控制受制于恶劣的环境和离散的温度样点分布,补偿困难,无法精确预测炉内各点的温度;传统的温度预测控制方法采用基于离散样本数据的最小二乘拟合方法,无法滤除冗余量干扰,实现平滑预测;提出一种内插连续预测的冶金精确温控实现方法,在炉内温度离散采集的基础上,通过温度值内插和平滑连续预测的方法,对采样的离散温度进行预测处理,算法沿用了一定的历史数据,具有更佳的预测性能;采用工业纯铁作为测试样本,仿真实验结果显示,基于内插连续预测的方法,炉内系统温度具有更加平滑的预测效果,温度稳定,对于精确温控预测具有很好的应用价值。 相似文献
7.
传统方法中采用二维层状纹理绘制方法生成草地动态视景,当草地出现层阶地势是草地视景的边界接缝处理不够理想,轮廓区域出现视觉的跳变。引入竖直纹理切片,对草地的视景生成进行优化,提出一种基于网络面偏移量递阶控制模型的草地视景生成算法,首先进行草地三维体纹理构造,采用高斯核平滑处理算法处理草叶数据,在草地动态模拟中,设计网络面偏移量递阶控制算法,根据草叶弯曲程度和地势平坦程度而自动进行网络面的层数调整的动态非均匀层递阶控制,消除视觉跳变现象。基于GPU可编程功能,实现不同大规模地形下风场作用下的草地动态视景生成模拟仿真。仿真实验表明,采用该方法进行草地动态实时模拟,能真实动态地模拟风力等作用下草地起伏视景,绘制执行效率和生动逼真性都优越于传统方法。 相似文献
8.
传统的基于二维小波变换的图像压缩方法在对高光谱图像细节部分进行量化编码时对低频部分进行全域矢量分解,噪点处理不够平滑,处理结果不好。提出一种改进的基于小波域子矢量的光谱图像压缩处理算法,对小波域的子矢量细节部分采用误差补偿编码的方法对高光谱图像的噪点进行平滑处理,对N级码书进行两级小波变换提取低频系数,通过算术编码实现城市、植被、水流多源信息高光谱图像压缩和解码恢复识别结果。仿真结果表明,采用该算法进行光谱图像压缩,图像经压缩处理后的恢复质量品质较高,峰值信噪比提高明显。 相似文献
9.
《科技通报》2015,(8)
通过对人体心脏器官的医学图像重建,为实现三维可视化手术及图像重构提供图像基础。传统的心脏医学图像重建方法采用的是三维坐标点动态数据采集算法,当测量点相对散乱时无法满足心脏器官重建的准确性要求。提出一种融入背景差分连续重构的心脏医学图像重建方法,进行图像细节纹理的灰度化图像进行提升分离,定义表面渲染的选项,计算二维层状图像纹理特征像素点检测沿幅角方向上模值的极大值点,得到三维成像的仿真视景图像的质心位置,采用二阶累积泰勒展开算法,对三维图像模型进行心脏图像的纹理特征提取,实现算法改进。仿真结果得出,采用该算法进行心脏医学图像重建,重建表面的最大误差显著减少,重建精度较高,重建时间减少,在实时性和精确性上性能优越。 相似文献
10.
《科技通报》2015,(8)
在浓雾环境下采集的视觉图像出现突兀点,需要进行平滑处理,提高对浓雾环境下的图像成像和识别能力。传统方法中采用差频控制的浓雾图像突兀点平滑处理算法,图像采集出现视觉偏移时平滑处理效果不好。提出一种基于视觉偏移修正的浓雾图像突兀点平滑处理算法,基于浓雾天气条件下单色大气散射模型,物体表面的反射光由于大气粒子的散射而损失,得到雾点散射损失,采用视觉偏移修正的算法,提高对浓雾图像的视觉偏移修正能力,由于起点坐标和视线方向出现视觉偏移,采用去雾滤波算法提高突兀点的平滑性能,得到浓雾图像的去雾滤波系统函数,通过边缘检测得到图像的突兀点平滑结构,进行Hough变换直线检测,实现视觉偏移修正和突兀点平滑改进。仿真结果表明,该算法具有较好的突兀点平滑处理性能,无论是细节还是浓雾图像的色彩都恢复得比较自然和清晰,去雾效果较好,平滑处理的图像有较高的配准率,展示了该算法的优越性能。 相似文献
11.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
12.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
13.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
14.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
15.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
16.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
17.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
18.
Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
19.
Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
20.
Leah A. Lievrouw 《The Information Society》1998,14(2):83-96
The main premise of this article is that in information societies generally, and in virtual social contexts particularly, a distinctive style of interaction to facilitate the communication of difference, heterotopic communication , has emerged. It rests on two cultural foundations: an ideological belief in the positive, socially integrating power of communication, and a prevailing ethic of instrumental rationality, subjective individualism, and strategically practiced self-interest. The former is demonstrated by the use of simulation and spectacle as sources of information; exhibitionism/voyeurism as a communicative style; and the awareness of surveillance. The latter is seen in the competitive use of knowledge as a commodity; a surface globalism masking deep parochialism; lateral as well as vertical information inequity; and the use of public versus private as strategies for engagement rather than as spaces. Those who engage in heterotopic communication resort to their 'own devices' both in the sense of personal agendas, strategies, interests, and interpretations, and in the form of the telecommunication tools that help realize them. These personal and technological devices allow individuals with the right educational and technical resources to avoid exposure to disagreement, difference, or other information that does not serve their direct purposes or reflect their particular views of the world; yet they also help convey the appearance of openness, availability, and cooperation. This style of interaction is used strategically in combination with information and communication technologies to gain social or economic advantages, but it may encourage social separatism and parochialism, inhibit the negotiation of disputes, and emphasize competing interests. 相似文献