Extended FRAG-BASE schema-matching method for multi-version open GIS Web services retrieval

The OGC Web Service (OWS) schemas have the characteristics of a complex element structure, are distributed and large scale, have differences in element naming, and are available in different versions. Applying conventional matching approaches may lead to not only poor quality, but also bad performance. In this article, the OWS schema file decomposition, fragment presentation, fragment identification, fragment element match, and combination of match results are developed based on the extended FRAG-BASE (fragment-based) schema-matching method. Different versions of Web Feature Service (WFS) and Web Coverage Service (WCS) schema-matching experiments show that the average recall of the extended FRAG-BASE matching for the schemas is above 80%, the average precision reaches 90%, the average overall achieves 85%, and the matching efficiency increases by 50% as compared with that of the COMA and CONTEXT matcher. The multi-version WFS retrieval under the Antarctic Spatial Data Infrastructure (AntSDI) data service environment demonstrates the feasibility and superiority of the extended FRAG-BASE method.     

多尺度地图面/面目标匹配模式及变化探测方法研究

多尺度地图数据更新的一个重要途径就是通过目标匹配技术获得已更新与待更新的不同比例尺地图之间表达同一地物的候选空间目标,并对候选匹配目标对进行比较,以便获得匹配目标间的差异以及发现未匹配的目标;进而,分析判断差异是否由该目标所表达的地理要素的实际变化所导致。该文以面目标匹配为例,对多尺度地图面目标匹配对的差异驱动因素和变化类型进行分析,针对不同模式的目标匹配对提出了利用长度差异、面积差异和重叠度指标进行差异驱动因素判别、变化探测和变化类型判定的方法,并验证了该方法的有效性和实用性。     

Life‐cycle cost assessment of RC and ECC frames using structural optimization

In this study life‐cycle cost (LCC) assessment of structural frames is performed. Two different materials, reinforced concrete (RC) and reinforced engineered cementitious composites (ECC), with different response characteristics are used to model the frames. ECC is characterized by high tensile ductility and energy absorption and reduced crack widths when compared to conventional concrete. However, the material is more expensive than conventional concrete; therefore, in order to quantify the potential benefits that could be obtained by replacing concrete with ECC, the life‐cycle performance is evaluated in an optimization framework. Three different structural frames are considered: an RC only frame, an ECC only frame and a multi‐material (MX) frame in which ECC is selectively applied at the potential plastic hinge locations while the remainder of the frame is made of RC. The structural capacity and earthquake demand are evaluated using rigorous analysis methods to capitalize on different characteristics of concrete and ECC, and both aleatory and epistemic uncertainties are incorporated into the LCC formulation. It is found that both the initial and LCC of frames that use ECC are lower due to savings in material and labor cost of transverse reinforcement for the former and due to increased capacity and reduced demand for the latter. Copyright © 2012 John Wiley & Sons, Ltd.     

一种顾及影像间位置关系的匀光方法

提出了基于矩匹配的色彩平衡算法,在顾及影像间位置关系的基础上将影像的均值和均方差映射到给定的数值,并且使不同区域的灰度均值和均方差近似相等,在尽量保持影像原有色调的条件下消除影像之间以及影像内部的色调和亮度差异。     

基于Harris和SURF的遥感图像匹配方法研究

针对多源遥感图像匹配正确率低的问题,本文首先采用点空间约束的Harris角点检测算法,得到分布比较均匀的角点;接着构建Voronoi图进行图像分块;然后应用分块SURF特征点检测和匹配得到仿射变换参数;再利用灰度积相关算法实现同名点搜索;最后辅以两点对空间约束剔除误匹配。实验结果表明,本文采用的基于Harris和SURF的方法在遥感图像匹配正确率和效率上优于SURF算法。     

倾斜影像的量测方法研究

随着“数字地球”“数字城市”的提出,能够快速获取空间数据基础信息成为当今急需解决的问题之一。传统的航空摄影测量主要是对地物顶部信息的获取,而对侧面信息获取比较困难,因此倾斜航空测量技术成为国内外快速发展起来的一门高新技术。本文主要论述了基于倾斜影像量测的几种方法,并对以后量测方法的发展趋势进行了说明。     

浅谈VirtuoZo和MapMatrix在3D产品中的应用

主要论述了数字摄影测量系统MapMatrix和VirtuoZo的一些异同点。     

利用外部DEM辅助山区SAR立体像对匹配及地形制图

SAR立体像对的匹配是利用雷达摄影测量技术提取地形高程信息的关键,匹配精度将直接影响结果 DEM的高程精度。针对山区SAR立体像对匹配过程中同名点选取困难的问题,引入外部粗分辨率DEM作为辅助数据,将该DEM高程转换为视差,为匹配提供初值,同时采用金字塔匹配策略,不仅可以缩小搜索范围,提高搜索效率,而且能够减少粗差的产生。试验结果表明,采用外部DEM辅助之后,匹配粗差点数量相对于传统的雷达摄影测量处理结果明显减少,从而有效地提高了高程信息提取重建的精度。     

3维最小二乘表面匹配泛型数学模型及在机载LiDAR条带平差中的应用

以3维表面间共轭点欧氏距离之和最小为理论基础,提出一种泛型3维表面匹配数学模型,并推导其最小二乘平差理论模型,利用该模型进行机载LiDAR点云条带平差。针对真实机载LiDAR点云数据进行条带平差对比实验,结果表明本文所提出的表面匹配模型,不仅能准确估计出相邻重叠3维表面间的正形变换参数,较好地解决机载LiDAR点云条带间配准问题,而且能同时适用于多种同名点对应准则,是一种泛型的配准模型。     

基于改进SIFT算法的视频图像序列自动拼接

本文提出了一种自适应帧采样和限定特征提取区域的拼接方法,根据帧间重叠率和帧间隔建立线性模型,并把各帧图像对准到其前后的关键帧上。在特征点提取方面,提出了一种改进的SIFT算法进行特征点提取,并采用随机采用一致性(RANSAC)方法来更新匹配点,在图像融合中采用线性加权渐入渐出的自然融合算法。实验结果表明:该方法对一般场景能稳定的抽取到关键帧,并进行拼接,取得了较好的拼接效果。