战场地理空间信息可视化系统设计与研究

对当前流行的3DGIS系统进行了介绍,并研究提出了采用面向对象的方法来表达3D场景中的空间数据,基于栅格金字塔模型来组织和管理地形数据,基于视点相关的地形LoD方法实现了大范围漫游,基于参数化3D建模方法和矢量地物LoD来实现地物数据的建模和可视化的方法,设计和构建西北地区战场地理空间信息可视化系统(3DMGIS)。     

高光谱数据的降维及Tabu搜索算法的应用

在高光谱影像的分类过程中,如何有效地降低特征空间的维数,又能保证原始数据所包含的丰富地物信息是一项十分重要而繁琐的工作.深入分析了这种降维的必要性,并针对当前常用的降维方法存在的问题,提出了运用Tabu搜索算法获取对分类最为有利的特征波段的思想.考虑到高光谱数据的特点,指出了算法运行中应该注意的若干关键参数设置问题.实验表明,Tabu搜索算法在求解质量和执行效率方面都有着良好的表现,可以用于高光谱数据的降维处理.     

多源遥感影像配准技术分析

图像配准技术是近年来发展迅速的图像处理技术之一,是图像融合、目标提取与定位、变化监测、高分辨率影像重建等处理工作不可缺少的步骤.首先给出了多源遥感影像配准的概念和基本过程,然后着重从匹配基元、转换函数、相似性测度、匹配策略4个方面对国内外现有的影像配准技术和方法进行了分析和评述,最后指出了影像配准技术所面临的主要难题和发展方向.     

在图形简化中面状目标间拓扑关系渐进式转换的研究

拓扑关系是空间关系中最为重要的关系,在空间抽象中,拓扑关系会发生变化,如何控制这种变化?如何在更抽象的层次上维护空间拓扑关系的一致性,就是一个非常重要的问题。本文以拓扑关系成分抽象的转换方法为基础,研究了面之间拓扑关系的抽象规则,并详细探讨了这些拓扑关系的渐进式转换方法,绘制了相应的面之间基本拓扑关系渐进式转换图。     

Cartographic Symbol Design Considerations for the Space–Time Cube

The cartographic representation of geographic phenomena in the space–time cube comes with special challenges and opportunities when compared with two-dimensional maps. While the added dimension allows the display of attributes that vary with time, it is difficult to display rapidly varying temporal data given the limited display height. In this study, we adapt 2D cyclic point symbols to construct 3D surfaces designed along a helical path for the space–time cube. We demonstrate how these complex?3D helical surfaces can display detailed data, including data reported daily over 100 years and data reported in four-hour intervals over a year. To create the point symbols, each value is plotted along the curve of a helix, with each turn of the helix representing one year or week, respectively. The model is modified by varying the radii from the time axis to all points using the attribute value, in these cases maximum daily temperature and four-hourly ridership, and then creating a triangulated surface from the resulting points. Using techniques common to terrain representation, we apply hue and saturation to the surface based on attribute values, and lightness based on relief shading. Multiple surfaces can be displayed in a space–time cube with a consistent time interval facing the viewer, and the surfaces or viewer perspective can be rotated to display synchronized variations. We see this method as one example of how cartographic design can refine or enhance operations in the space–time cube.     

Re-examining urban region and inferring regional function based on spatial–temporal interaction

Urban system is shaped by the interactions between different regions and regions planned by the government, then reshaped by human activities and residents’ needs. Understanding the changes of regional structure and dynamics of city function based on the residents’ movement demand are important to evaluate and adjust the planning and management of urban services and internal structures. This paper constructed a probabilistic factor model on the basis of probabilistic latent semantic analysis and tensor decomposition, for purpose of understanding the higher order interactive population mobility and its impact on urban structure changes. First, a four-dimensional tensor of time (T)?×?week (W)?×?origin (O)?×?destination (D) was constructed to identify the day-to-day activities in three time modes and weekly regularity of weekday/weekend pattern. Then we reclassified the urban regions based on the space clustering formed by the space factor matrix and core tensor. Finally, we further analysed the space–time interaction on different time scales to deduce the actual function and connection strength of each region. Our research shows that the application of individual-based spatial–temporal data in human mobility and space–time interaction study can help to analyse urban spatial structure and understand the actual regional function from a new perspective.     

关于我国天测与测地VLBI网络未来建设的讨论

结合国内外VLBI技术发展的历史、现状与动态,从天体测量、空间大地测量和深空探测等角度,对我国天测与测地VLBI观测网络的未来建设进行了需求分析和测站配置技术指标分析。     

利用四元数描述线阵CCD影像的空间后方交会

将四元数理论引入高分辨率线阵CCD影像的空间后方交会解算中,提出了一种利用四元数描述线阵CCD影像的单片空间后方交会方法。该方法利用四元数描述角度旋转矩阵,对严格的共线条件方程进行线性化,并采用正则化的数学方法克服线阵CCD影像外方位元素的相关性。试验证明了本算法的正确性和可靠性。     

基于小波包分解的结构自振特征提取及多路径误差分离

为了准确获取结构自振特性,通过分析多路径误差和结构振动的频率特征,采用小波包分解和频谱分析相结合的方法,在不同尺度下进行特定成分的提取,再作频率特性分析。实验结果表明,小波包能够有效地分离多路径误差,实现结构振动特征的提取,GPS测定的结构自振频率与理论值吻合较好,并且具有很好的稳定性。     

基于面片裁切技术的点云轮廓线生成算法

随着点云在各个领域的广泛应用,对点云处理相关技术的研究更为活跃。目前,研究的热点主要集中在点云去噪、配准、分割、增强、特征提取和重建等方面。其中,特征提取起着承前启后的作用,具有十分重要的研究价值。基于面片裁切技术的点云轮廓线生成算法。首先,对点云数据进行面片提取,通过面片生长、融合生成特征面片,并根据提出的面片双向索引法快速构造特征线,最终实现点云平面轮廓线的生成。实验证明,本算法可快速、准确、有效地实现点云轮廓线的生成。