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311.
基于本体的地理空间信息集成框架与实现 总被引:1,自引:0,他引:1
论述了地理本体的基本概念、结构,介绍了地理本体的建模方法,提出了基于地理本体的空间数据集成框架,包括构建地理本体、数据预处理、概念映射、数据映射和数据抽取与转换5个步骤;设计了基于本体的空间数据集成方案,以数字地形图数据、海图数据向标准本体的集成为例对方案进行验证试验,并取得了初步成果。 相似文献
312.
Wenbin Shen Jin Li Jiancheng Li Zhengtao Wang Jinsheng Ning Dingbo Chao 《地球空间信息科学学报》2008,11(4):273-278
Given the second radial derivative Vrr(P) |δs of the Earth's gravitational potential V(P) on the surface δS corresponding to the satellite altitude, by using the fictitious compress recovery method, a fictitious regular harmonic field rrVrr(P)^* and a fictitious second radial gradient field V:(P) in the domain outside an inner sphere Ki can be determined, which coincides with the real field V(P) in the domain outside the Earth. Vrr^*(P)could be further expressed as a uniformly convergent expansion series in the domain outside the inner sphere, because rrV(P)^* could be expressed as a uniformly convergent spherical harmonic expansion series due to its regularity and harmony in that domain. In another aspect, the fictitious field V^*(P) defined in the domain outside the inner sphere, which coincides with the real field V(P) in the domain outside the Earth, could be also expressed as a spherical harmonic expansion series. Then, the harmonic coefficients contained in the series expressing V^*(P) can be determined, and consequently the real field V(P) is recovered. Preliminary simulation calculations show that the second radial gradient field Vrr(P) could be recovered based only on the second radial derivative V(P)|δs given on the satellite boundary. Concerning the final recovery of the potential field V(P) based only on the boundary value Vrr (P)|δs, the simulation tests are still in process. 相似文献
313.
扩展了现有的属性委托授权机制的二值信任为主观区间信任,提出了可信角色和信任约束概念的定义,建立了依据角色信任评估的角色委托控制策略,建立了依据实体信任评估的授权控制规则,给出了委托策略中实体信任度递减的计算方法,将这些策略和规则用逻辑的语法形式表示,并进一步对逻辑程序赋予计算推导的语义,在属性委托授权机制的逻辑语义基础上实现了委托和授权的主观信任控制。 相似文献
314.
Synthetic aperture radar (SAR) image formation for a ground moving target necessitates the compensation of the unknown target trajectory. The keystone transform has been employed to remove the linear component of the range migration for the moving target, where interpolation is required. In this letter, a realization of the keystone transform avoiding interpolation is presented. The kernel of this transform, i.e., the range-frequency-dependent azimuth time rescaling, is implemented using only complex multiplications and fast Fourier transforms based on the scaling principle, which has been successfully applied in the equalization of the space-variant range cell migration in SAR processing. In addition, the moving target is coarsely focused according to the SAR geometry and the platform velocity while exploiting the scaling principle. This preliminary focusing is helpful in the isolation of the moving target from ground clutter, so as to facilitate a more refined processing with respect to each mover. SAR raw data combined with simulated echoes of moving targets are utilized to validate the presented approach 相似文献
315.
Automatic Extraction of Power Lines From Aerial Images 总被引:1,自引:0,他引:1
Guangjian Yan Chaoyang Li Guoqing Zhou Wuming Zhang Xiaowen Li 《Geoscience and Remote Sensing Letters, IEEE》2007,4(3):387-391
There has been little investigation for the automatic extraction of power lines from aerial images due to the low resolution of aerial images in the past decades. With increasing aerial photogrammetric technology and sensor technology, it is possible for photogrammetrists to monitor the status of power lines. This letter analyzes the property of imaged power lines and presents an algorithm to automatically extract the power line from aerial images acquired by an aerial digital camera onboard a helicopter. This algorithm first uses a Radon transform to extract line segments of the power line, then uses the grouping method to link each segment, and finally applies the Kalman filter technology to connect the segments into an entire line. We compared our algorithm with the line mask detector method and the ratio line detector, and evaluated their performances. The experimental results demonstrated that our algorithm can successfully extract the power lines from aerial images regardless of background complexity. This presented method has successfully been applied in China National 863 project for power line surveillance, 3-D reconstruction, and modeling. 相似文献
316.
317.
单人智能测绘系统主要由野外用加固型便携式计算机、高精度GPS接收机、专业软件组成,可以实现单个测量员承担全流程测量作业,高效地进行成图与更新。系统集成创新了现代测绘技术手段,其精度适用于各种不同比例尺地图的测绘与更新,成为信息化测绘体系中的现代测绘技术装备之一。 相似文献
318.
319.
ZHANG Yi YAN Li 《地球空间信息科学学报》2007,10(4):276-281
A scheme for an automatic road surface modeling from a noisy point cloud is presented. The normal vectors of the point cloud are estimated by distance-weighted fitting of local plane. Then, an automati... 相似文献
320.
CHEN Luyao YUE Jianwei JIANG Weiguo LI Jing CHEN Yunhao 《地球空间信息科学学报》2007,10(4):299-302
The unceasing change problem of land information systems can be resolved through the refactoring and design pattern. To promote the implementation of design pattern and refactoring methods in developin... 相似文献