An efficient image-mosaicing method based on multifeature matching

Mosaicing is connecting two or more images and making a new wide area image with no visible seam-lines. Several algorithms have been proposed to construct mosaics from image sequence where the camera motion is more or less complex. Most of these methods are based either on the interest points matching or on theoretical corner models. This paper describes a fully automated image-mosaicing method based on the regions and the Harris points primitives. Indeed, in order to limit the search window of potential homologous points, for each point of interest, regions segmentation and matching steps are being performed. This enables us to improve the reliability and the robustness of the Harris points matching process by estimating the camera motion. The main originality of the proposed system resides in the preliminary manipulation of regions matching, thus making it possible to estimate the rotation, the translation and the scale factor between two successive images of the input sequence. This estimation allows an initial alignment of the images along with the framing of the interest points search window, and therefore reducing considerably the complexity of the interest points matching algorithm. Then, the resolution of a minimization problem, altogether considering the couples of matched-points, permits us to perform the homography. In order to improve the mosaic continuity around junctions, radiometric corrections are applied. The validity of the herewith described method is illustrated by being tested on several sequences of complex and challenging images captured from real-world indoor and outdoor scenes. These simulations proved the validity of the proposed method against camera motions, illumination variations, acquirement conditions, moving objects and image noise. To determine the importance of the regions matching stage in motion estimation, as well as for the framing of the search window associated to a point of interest, we compared the matching points results of this described method with those produced using the zero-mean normalized cross correlation score (without regions matching). We made this comparison in the case of a simple motion (without the presence of a rotation around optical axis and/or a scale factor), in the case of a rotation and in the general case of an homothety. For justifying the effectiveness of this method, we proposed an objective assessment by defining a reconstruction error.

Oracle 7的空间数据管理技术

由于空间数据的非结构化特点,传统的管理方法是采用文件系统,导致数据一致性、完整性及完全性等问题。如何利用数据库技术管理空间数据是同行关注的问题。Ｏｒａｃｌｅ７的空间数据管理技术成功解决了两个关键问题：如何在单一数据库中存取及管理不同类型的数据;如何改善拥有浩翰空间数据的空间数据库的性能。本文拟详细分析和讨论该技术。     

基于感兴趣区的图象近无损压缩

无损感兴趣区（Lossless Region of Interest (ROI)图象压缩方法,即在感兴趣区采用无损压缩,而在其他区域采用有损压缩,从而保证了重要信息不丢失,并尽可能提高衅象的压缩比,在整形小波变换（IWT）和嵌入式零树编码的基础上,实现了无损感兴趣区（Lossless ROI)的图象近无损压缩,并提出了一种小波变换域形状编码算法－－树映射形状编码,同时给出了算法的原理及实现,并进行了相关实验,实验结果表明,该算法能够提高压缩效率,且压缩效率取决于感兴趣区的大小以及对不感兴趣区图象的质量要求。     

改进的拼凑算法实现水印嵌入和盲检测

提出一种改进的拼凑算法,用来在空间域实现水印的嵌入和盲检测,算法在不影响原始图像视觉效果的基础上,对常见的图像攻击具有较好的鲁棒性.水印检测不需要原始图像的参与,有效实现了盲检测.     

基于冬季适老风环境模拟的寒地建筑形态优化方法

严寒地区冬季漫长而寒冷,人口老 龄化严重,而老年人作为健康状况相对脆弱 的群体,是寒地冬季室外公共空间的主要使 用者,如何通过合理的建筑布局营造更为舒 适的室外公共空间是亟待解决的科学问题。 本文通过现场实测结合问卷调查、SPSS数 理统计等方法实证研究冬季室外各种环境因 素对老年人活动舒适度的影响机制。分析结 果显示,在极低的室外温度作用下,风速成 为影响老年人室外活动舒适度的主要因素, 进一步结合TS-Givoni指标归纳出在严寒地 区特殊气候条件作用下的室外风速限值。基 于此对黑龙江省博物馆改扩建设计的多种空间形态风环境进行CFD模拟及评估优选,尝试对建筑设计形态优化提供理论方法指导。     

融合区域和全局特征提取的医学图像检索技术

针对胸部CT扫描图像库,提出了一种融合区域和全局特征提取的医学图像检索方法。为了提取局部感兴趣区域,给出了一种基于灰度层共现矩阵的区域增长算法,分割出病灶区域,再结合迭代阈值算法进行病灶边界的磨合。为了避免身体姿势问题造成的图像角度差异,利用具有旋转不变性的Zernike矩提取图像的全局特征,融合感兴趣区域的形状和分布特性以及整幅图像Zernike矩全局特征作为图像匹配准则的客观依据。实验结果表明,该算法能够比较有效地应用于基于内容的医学图像检索系统中。     

Constructing a typology of H2 in cities and regions: An international review

This paper primarily develops a seven-fold conceptual typology of place-based hydrogen initiatives. Through an international review of place-based hydrogen initiatives we reveal a plethora of projects, demonstrations, test-beds, ambitions and expectations at a wide range of spatial scales. We ask whether there is anything distinctive about how these different spatial scales attempt to develop the hydrogen economy. In particular, we seek to identify whether patterns emerge around the social interests involved at different scales of activity and the degree to which hydrogen links to different place-based agendas—political and resource autonomy, economy and employment. The paper addresses these questions and draws out a series of three key conclusions. First, there is wide ranging and significant diversity in the motivations for cities and regions to become involved in hydrogen economy developments—wider than conventional energy policy objectives. Second, there are still significant overlaps between different scales of action. Third, there is a tension between the more bounded concepts of using hydrogen to build self-reliance at a particular scale and those initiatives oriented around developing a more systemic technological system which is rolled out elsewhere. Finally, we argue that a key issue for further research is in understanding the social interests and institutions that attempt to both learn from across these activities at different scales and provide some sense of coordinated action between them. In our review the role of corporates—rather than national government—seems to be critical to such attempt to provide coordination across places and needs to be the focus of further research.     

蜀地"三国演义"漫谈成都当前的建筑创作格局

针对当前成都三种建筑创作“势力”鼎足的局面,文章研究了来自境外设计机构、国内发达地区和蜀地本土设计力量的博弈,评述了他们各自的创作特点、影响力和发展趋势,并对今后成都的建筑创作格局,尤其是本土力量的创作进行了展望。     

超大规模MIMO系统中基于交叠可视区域的功率分配方法

该文解决了超大规模多输入多输出(MIMO)系统中不同用户的可视区域(VR)存在相互交叠时的下行功率分配问题。考虑单个基站服务多个单天线用户的超大规模MIMO通信场景,由于基站配备的阵列较大,各个用户受障碍物遮挡仅能与基站部分天线进行通信,这部分天线即为各用户的可视区域。该文考虑不同用户的可视区域分布两两交叠,并依此划分子阵,并在各子阵上进行规则化迫零预编码以降低复杂度。接着基于大维随机矩阵理论,推导了系统下行遍历和速率的确定性近似表达式。然后,通过最大化该表达式,给出了基于统计信道状态信息的最优用户功率分配方法的闭式解。最后,仿真结果表明,和速率近似表达式的精度很高,所提功率分配方法能有效提高系统性能。     

中国天然气市场可持续发展分析

承接2016年回暖之势,2017年中国天然气市场迎来爆发式增长,全年天然气消费量达2 335×10~8 m~3、年消费增量达353×10~8 m~3。为此,有必要剖析推动中国天然气市场爆发式增长的主要因素并预测其未来发展的可持续性。研究结果表明:(1)2017年爆发式增长主要受益于宏观经济形势好转、大气污染防治措施深入实施、化工等大宗产品价格回升、华东地区天然气发电负荷增加、管道天然气供应价格相对较低、LNG汽车市场整体呈现回暖态势等因素;(2)经济发展形势、"煤改气"的推进、政策实施方向、油气价格趋势等外部因素将能继续支持天然气市场的快速增长;(3)但天然气产业的自身条件、资源和基础设施条件将对市场发展造成制约。结论认为:(1)2020年之前我国天然气市场需求量仍会保持快速增长的趋势,但难以维持每年300×10~8 m~3的增长规模;(2)工业燃料和发电是天然气市场发展的主要方向;(3)环渤海等地区是未来天然气需求量增长的主要区域。为了保持我国天然气市场的发展态势,提出如下建议:(1)千方百计扩大天然气供应规模,在认真做好国产非常规天然气资源开发的同时,积极落实进口天然气资源;(2)毫不松懈地建设基础设施,管道要超前建设,LNG接收站要加大力度建设,地下储气库等调峰设施要鼓励建设;(3)科学合理地理顺天然气价格,居民价格与非居民价格并轨首当其冲,确立价格是平衡供需关系的杠杆作用,减少行政干涉。