基于Java3D的网络地理信息可视化

在分析WebGIS中地理信息可视化研究现状的基础上，详细介绍了Java3D开发库的基本开发机制，并讨论其关键技术与解决方案，成功实现了基于Java3D的网络地理信息Web浏览器。实验表明，通过Java3D建立数字球面，并利用Java3D空间数据模型表达地理信息模型，实现在数字球面上映射地理信息，是实现网络地理信息可视化的新途径和新思路。     

数字地球网格计算雏议

数字地球将为人类提供关于我们地球的海量自然和人文数据与信息 ,是我们生活的行星的一个多分辨率 ,四维虚拟表达。网格计算被认为是解决数字地球问题的最好方法。数字地球问题的解决必须通过异构的计算资源 ,信息系统 ,设备 ,人之间的相互协作 ,而这些都是地理位置或组织结构分散的。本文介绍我们在生成用于解决数字地球问题的核心中间件的研究工作以及结果。因为网格计算本身是一门比较新的领域 ,网格计算与数字地球的有机结合将为数字地球提供一个全新的计算工具     

Kaiser filter for antialiasing in digital photogrammetry

Image aliasing is a problem appearing as artefacts in digitally resampled images, which degrades the quality of the image. In digital rectification and texture mapping, pixels from an input image are transformed to pixels of an output image. The discrete nature of a digital image causes aliasing in the transformed image. In this paper the source of aliasing and the theory of antialiasing are described. The necessity of a precise filter design in antialiasing is discussed and a filter based on a Kaiser adjustable window is designed. Different practical antialiasing methods are described as well as interpolation methods, which are conventional in photogrammetry. Selected antialiasing methods are implemented and applied to a close range image. An objective analysis is carried out by applying inverse transformations to rectified images and deriving some measures to estimate the information loss for each method by comparing original and reconstructed images. Results indicate that interpolation methods are not capable of removing or reducing aliasing in highly decimating transformations. The output images of interpolation methods therefore suffer from edge corruption and interfusion of small features. Applying a Kaiser filter with a precise antialiasing method results in the least information loss and considerably reduces aliasing at the expense of higher computation load.     

Coastal cliff retreat rates at Beit‐Yannay,Israel, in the 20th century

Research indicates that the aeolianite (Kurkar) cliffs along the Israeli Mediterranean coastline have continuously retreated eastward during the last few decades. There seems to be no dispute among Earth scientists regarding the general trend of cliff retreat. However the majority of papers displaying cliff retreat rates are based upon comparison of aerial photographs. Their lack of advanced geometric measurement methods causes a high margin of error. Public attention is focused upon the Beit‐Yannay coastal cliff since private homes are located along the southern section of the cliff crest. The current research compares the historic location of the cliff crest edge at Beit‐Yannay as observed in a series of aerial photographs taken during the period 1918–2000. Quantitative measurement methods included applications of satellite geodesy and digital photogrammetry and mapping. Research results offer quantitative, consecutive and highly accurate data regarding retreat rates over a relatively long period of 82 years. It is concluded that: 1. Annual average cliff retreat rates of the cliff crest is 20 cm/year. 2. Categorization of the study time span reveals periods displaying varying retreat rates such as 27 cm/year during 1918–1946, 21 cm/year during 1946–1973 and 10 cm/year during 1973–2000. 3. Maximum retreat distances of the cliff crest, over the study period were found to be approximately 25 m along the northern, lowest section of the cliff. Minimum distances of 11 m were identi?ed at the highest, southern section of the cliff. 4. The eolianite (Kurkar) cliffs along the Israeli Mediterranean coast throughout the 20th century have been an important source of sediment, contributing approximately 24 × 10⁶ m³ of sediments to the sediment balance of Israeli beaches. Copyright © 2004 John Wiley & Sons, Ltd.     

Application of lidar digital terrain modelling to predict intertidal habitat development at a managed retreat site: Abbotts Hall,Essex, UK

A key question in designing any managed retreat site concerns the nature of the habitats which will be created, and their likely long‐term sustainability and development. Studies of historical sea wall failures in Essex have shown that former reclaimed areas may respond to renewed tidal ?ooding in different ways depending on a number of factors, most importantly the elevation of the land at the time of breach, which governs the frequency and duration of tidal ?ooding. This paper demonstrates how digital terrain modelling using airborne lidar data can be used to calculate the elevation of the land behind a breach and to predict the likely habitats which will be created. When combined with data from sites of historical sea wall failure, predictions can also be made about the likely geomorphological and biological evolution of the created habitats in the longer term. At Abbotts Hall on the northern side of Salcott Creek, Essex, where a managed retreat scheme was activated in October 2002, the highest areas above 2·35 m OD were predicted to develop stable saltmarsh, intermediate areas between 2·1 and 2·34 m OD to develop potentially unstable saltmarsh which is likely undergo internal dissection, and the lowest areas below 2·1 m OD to remain as mud?at or lagoon. Approximately 38 per cent of the site was predicted to develop stable saltmarsh, and nearly 50 per cent to remain as lagoon or mud?at. Monitoring is now being undertaken but it will be several years before the accuracy of the predictions can be assessed. Copyright © 2004 John Wiley & Sons, Ltd.     

昆明区域数字遥测台网技术系统的改进及完善

昆明区域数字遥测台网从开始建设至今,一系列台网软件的相继研制并完善,特别是解决了数字地震仪系统传递函数的计算、定位精度、地震震级、大地震信息发布等相关的一系列技术难题,通过对技术系统的改进和完善,地震监测和大震速报相对于以往的模拟台网取得了长足的进步。从1999年11月25日的澄江5.2级地震,到2003年11月15日的鲁甸5.1级地震共18次5级以上地震,昆明台网都以快速准确的地震参数向中国地震局和云南省地震局速报,为抗震救灾争取了宝贵的时间,得到了云南省和云南省地震局的一致好评,在云南的防震减灾事业中做出了相应的贡献。     

山西数字遥测地震台网各子台台址地脉动噪声分析

通过对山西数字遥测地震台网11个子台台址背景噪声进行分析和计算，得出了各台址背景噪声地脉动速度均方根值(RMS值)、观测动态范围、噪声信号功率谱。结果表明各台址背景噪声水平基本符合数字地震观测技术规范要求。     

数字海图无缝拼接方法研究

在分析相关理论的基础上，提出了拼接前的数据要求，并给出了实现数字海图逻辑无缝拼接的具体步骤和无缝数据结构。论述了实现数字海图无缝拼接的意义。     

高分辨率数字航测相机现状和思考

本文根据国内外数字航测相机发展的实际情况，对于新型数字航测相机视场角、影像分辨率、像移补偿、摄影间隔和影像存贮器容量、相机系统的动态定位与定向以及真彩色与多光谱摄影等技术问题进行了分析并给出了相应的结论。     

月球探测摄影测量数据处理系统方案分析

本文提出了月球摄影测量数据处理系统的设计原则，探讨了月球摄影测量数据处理系统的组成和研究的内容，分析了在月球探测摄影测量数据处理中，首先应该解决的关键技术问题。结论：对月球探测摄影测量数据处理系统的研究，可以保障月球探测卫星工程测绘月球表面三维影像图及地形图任务的完成，同时，也可以为后续的月球探测计划提供摄影测量的基础理论、技术、方法和实践经验。