海图深度基准面传递算法的精度分析     

孙新轩  刘雁春  暴景阳  靳军 《测绘学院学报》2009,(3)

基于最小二乘潮位拟合传递法的数学模型,对短期验潮站海图深度基准面确定方法进行了研究。用实例对所提方法和《海道测量规范》中求取短期验潮站海图深度基准面方法进行了分析比较;探讨了影响最小二乘潮位拟合传递法精度的因素。结果表明:最小二乘潮位拟合传递法用于确定短期验潮站海图深度基准面,具有较高精度,并且可从同步时间、地理环境及站间距离等方面进一步提高该法所得海图深度基准面的精度。  相似文献   

基于双重网格的矢量地图数字水印算法   总被引：1，自引：0，他引：1       下载免费PDF全文

车森  邓术军 《海洋测绘》2008,28(1):13-17

通过分析数字水印技术和矢量地图的结合方式，提出了一种基于双重网格的数字水印算法，该算法通过双重网格划分，将水印信息分散隐藏到节点坐标的最低有效位上。实验证明，该算法具有良好的隐蔽性、较强的鲁棒性，可以抵抗常规的节点编辑和地图裁切对水印信息的破坏，适合于矢量地图的版权保护。  相似文献   

基于Web服务的海洋矢量场远程可视化研究   总被引：2，自引：2，他引：0  

杨峰  杜云艳  苏奋振  肖如林 《地球信息科学学报》2008,10(6):749-756

目前,GIS大部分空间数据的静态网络可视化共享及其服务器端数据集中管理提供底层数据服务的方式,不仅难以满足与日剧增的多源异构海量空间数据共享需求,同时从应用角度也难以满足对动态性较强的海洋环境信息进行实时可视化共享的需求。而网络Web服务和网格技术的快速发展及其与网络GIS的有机结合,使得分布式、一站式的空间数据实时动态网络可视化共享成为可能。因此,本文针对海洋矢量场信息,深入分析其网络实时动态可视化需求及相应的技术难点,并以Web服务为基础,探讨了在Web服务与网络GIS技术基础上建立一站式海洋环境矢量场网络动态可视化共享系统的技术方法和具体系统结构。文章最后以海洋流场数据为例,具体采用ArcGIS Server的网络服务技术,以及Arc Engine的高效可视化技术,具体实现海洋流场的网络动态可视化共享平台。实践证明,基于Web服务的海流网络可视化系统较好地满足了用户对矢量场数据网络共享与可视化的需求。  相似文献   

测量平差中求解协因数的简化算法   总被引：3，自引：1，他引：2  

杨雪峰  龚涛  汪精河 《测绘科学》2009,34(1)

本文从测量平差精度评定的求解协因数阵的过程中,寻找了一种有关协因数阵的简便算法,此算法的特点在于从已知的解法中,提炼出一种便于理解和记忆的方法,从经典的平差解答中找出规律,从而避免了去死记硬背复杂的结论。本文针对提出的简便算法,在条件平差、间接平差、附参数的条件平差和附限制条件的间接平差中通过验证,结果是正确的。  相似文献   

Correlation methods of base-level cycle based on wavelet neural network     

Xingke XU  Changwei CHEN  Jing SUN  Qinglong MENG College of Earth Sciences  Jilin University  Changchun  China 《东北亚地学研究》2007,10(1):25-28

The authors discussed the method of wavelet neural network(WNN) for correlation of base-level cycle.A new vectored method of well log data was proposed.Through the training with the known data set,the WNN can remenber the cycle pattern characteristic of the well log curves.By the trained WNN to identify the cycle pattern in the vectored log data,the ocrrelation process among the well cycles was completed.The application indicates that it is highly efficient and reliable in base-level cycle correlation.  相似文献   

A lightweight ensemble spatiotemporal interpolation model for geospatial data     

Shifen Cheng  Peng Peng 《International journal of geographical information science》2020,34(9):1849-1872

ABSTRACT

Missing data is a common problem in the analysis of geospatial information. Existing methods introduce spatiotemporal dependencies to reduce imputing errors yet ignore ease of use in practice. Classical interpolation models are easy to build and apply; however, their imputation accuracy is limited due to their inability to capture spatiotemporal characteristics of geospatial data. Consequently, a lightweight ensemble model was constructed by modelling the spatiotemporal dependencies in a classical interpolation model. Temporally, the average correlation coefficients were introduced into a simple exponential smoothing model to automatically select the time window which ensured that the sample data had the strongest correlation to missing data. Spatially, the Gaussian equivalent and correlation distances were introduced in an inverse distance-weighting model, to assign weights to each spatial neighbor and sufficiently reflect changes in the spatiotemporal pattern. Finally, estimations of the missing values from temporal and spatial were aggregated into the final results with an extreme learning machine. Compared to existing models, the proposed model achieves higher imputation accuracy by lowering the mean absolute error by 10.93 to 52.48% in the road network dataset and by 23.35 to 72.18% in the air quality station dataset and exhibits robust performance in spatiotemporal mutations.  相似文献   

澳门居民对“自由行”政策支持意向研究:地方依恋的调节作用     

胡孝平  李玺 《世界地理研究》2019,28(2):179-190

居民态度是影响旅游地持续发展的关键因素。借助态度ABC模型的标准学习层级理论，运用结构方程模型研究澳门居民对自由行政策支持意向的形成机理，并对地方依恋在其中的调节作用进行验证。结果表明：澳门居民对自由行政策支持意向主要受正面影响感知和积极情感的影响，澳门居民对自由行政策的经济与社会作用感知能激发其对旅游发展的满意感，并抑制对内地自由行游客的厌恶感，社会成本感知将导致居民对自由行游客的厌恶感，居民满意感对其支持行为意向有显著正向影响，地方依恋在澳门居民态度形成过程中发挥部分调节作用。根据研究结论，提出了提升澳门居民对自由行政策支持意向的管理举措。  相似文献   

Crop characterization using an improved scattering power decomposition technique for compact polarimetric SAR data     

《International Journal of Applied Earth Observation and Geoinformation》2020

Crop characterization using Compact-Pol Synthetic Aperture Radar (CP-SAR) data is of prime interest with the rapid advancements of SAR systems towards operational applications. It is noteworthy that as a good compromise between the dual and quad-polarized SAR systems, the CP-SAR offer advantages in terms of the larger swath and lower data rate. The m − χ CP decomposition considers two out of the three Stokes child parameters: degree of polarization (m), ellipticity (χ), and orientation angle (ψ) to describe the polarized part of the quasi-monochromatic partially polarized wave. An improvement in the scattering powers was proposed in the S − Ω decomposition, which takes into accounts both the transmitted and received wave ellipticities (χ_t, χ_r) and the orientation angles (ψ_t, ψ_r). In this decomposition, S denotes the Stokes vector and Ω is the polarized power fraction. However, it may be noted that the S − Ω decomposition intrinsically ignores dominance in the target scattering mechanism while calculating the powers. In this work, improvement is proposed for the S − Ω decomposition by utilizing the degree of dominance in the scattering mechanism. The improved S − Ω (named as iS − Ω) decomposition powers are first compared with the existing m − χ and S − Ω powers for elementary (viz., trihedral and dihedral corner reflectors) and distributed targets using simulated CP-SAR data from quad-pol RADARSAT-2 data. An increase of ∼2% for odd and even-bounce powers obtained from the iS − Ω decomposition is observed for the trihedral and dihedral corner reflectors respectively. The analysis of the scattering powers for distributed targets shows that an increase of 15% and 12% in the even and odd-bounce powers is observed from iS − Ω for urban and bare soil areas respectively as compared to the m − χ and S − Ω decompositions. Besides, temporal variations in the scattering powers obtained from the iS − Ω decomposition are also analyzed for rice, cotton, and sugarcane crops at different growth stages.  相似文献   

影像地形图产品模式设计与关键技术     

杨辉山  林超  雷丽珍  戴江鸥 《测绘通报》2020,(5):138-141

以广东省1：10 000影像地形图为例，在需求调研分析和生产试验的基础上，设计了影像地形图产品模式，探讨了等高线生成、高程点提取、矢量要素选取、注记及其符号化、图廓整饰等关键技术，研制了相应的生产工艺和技术方法，并制作了产品样本。该研究成果已形成系列技术文档，可为影像地形图的设计和规模化生产提供参考。  相似文献   

Public Support for Land Acquisition: A Key Instrument for Successful Land Conservation,Governance and Management     

Beatrice Frank  Michael Walton  Rick Rollins 《社会与自然资源》2019,32(6):720-729

While it is recognized that protected areas are important for biodiversity conservation and human wellbeing, governments struggle to establish and/or enlarge protected areas. Land acquisition and the challenges encountered by governing institutions in funding protected area systems expansion is discussed in this paper using the Capital Regional District (CRD) Land Acquisition Fund as a case study. We briefly discuss land acquisition in British Columbia and in the CRD, and offer an overview of the CRD Land Acquisition Fund and the public participation process that led to its establishment. We emphasize the importance of developing political and citizen support, and a shared vision about expanding protected areas systems - a key element for nearly doubling the parkland base of CRD Regional Parks in less than 20?years. We conclude by offering the lessons learned through the case study and provide guidance for policy and governance directions with regard to land acquisition.  相似文献