A tile-based method for geodesic buffer generation in a virtual globe

Geometric buffers are important for spatial analysis in many applications of geographic information systems (GISs), such as environmental measurement and management, human health, urban planning, etc. Geometric buffer generation algorithms are well studied in the Euclidean space where the buffer distance is measured by Euclidean metrics; however, very few algorithms are available for generating geometric buffers on the terrain surface in a virtual globe where the buffer distance is measured by geodesic metrics. This paper proposes a tile-based method for geodesic buffer generation according to the characteristics of a virtual globe. It extends the vector tile model (VTM) to organize terrain and vector data, and the XYH algorithm is improved to build geodesic distance fields for terrain meshes. Based on the data organization and the improved XYH algorithm, a geodesic buffer is generated via three main steps: selecting and assembling tiles, updating geodesic distance fields and tracing the boundaries of buffer zones. This method is implemented with multi-scale terrain and vector data, and the experimental results show that it is valid and exact and can be applied in practical applications.     

Synthetic seismic illumination of small-scale growth faults,paralic deposits and low-angle clinoforms: A case study of the Triassic successions on Edgeøya,NW Barents Shelf

Fault activity and sandstone-body geometries and spread, all bear significant weight to understanding the potential hydrocarbon systems on the NW Barents Shelf. Synthetic seismic modelling of onshore sedimentary successions provides insight into the seismic resolution and expression of various sedimentological features on Edgeøya: (i) sandy growth basins in pro-delta mudstones (ii) paralic sedimentary deposits and (iii) low-angle tidally influenced progradational successions.Synthetic modelling suggests that the lithological contrast associated with sand-infilled growth basins in pro-deltaic shales, even with offsets as small as 50–75 m, will create distinct geometries in seismic data. Modelling suggests that while optimal 90° illumination, low frequency bands and more typical sedimentary velocities around 2000 m/s will generate very clear discernible growth faults, the angular lithological contrast should generate discernible features even with the high velocities and typical 20–30 Hz frequency band of seismic sections on the NW Barents Shelf. Comparing to actual seismic data in which multiples, noise and in places overburden are influential, it is possible to identify growth-fault geometries more confidently, and to link them to larger planar fault activity.Modelling other features identified in the paralic sedimentary system it is apparent that many of the massive channel or lenticular shaped sandstone bodies should be identifiable in the actual seismic, although their expression is less distinct and more easily misinterpreted than that of growth faults. It is apparent that features such as igneous intrusions, unless imaged in a “perfect” survey, can be difficult to properly identify, particularly near-vertical connections. The velocity contrast creates strong impedance along horizontal sections, but heavily fractured igneous intrusions with lower velocities could easily be assumed to be isolated sandstone bodies. While the modelling appreciates the overall wedging nature of the successions, the simplified lithological observations onshore cannot predict the probable erosion/condensation contrast associated with low-angle clinoforms which are visible in the seismic data, and hence not reproduce them easily in the models.     

National Virtual Core Library HyLogging data and Ni–Co laterites: a mineralogical model for resource exploration,extraction and remediation

The National Virtual Core Library (NVCL) HyLogging core-scanning system generates mineralogical information from visible, short-wave infrared and thermal infrared spectroscopic data. Currently, HyLogging data are freely available for more than 1500 drill holes via the AuScope Discovery Portal and various Geological Survey websites. With any new technology, there is commonly a lag between provision and take-up by users that can be aided by the publication of case studies in the scientific literature. This paper uses the Mt Davies nickel–cobalt (Ni–Co) laterite deposits, located in northwest South Australia, as a case study to assess the accessibility and representation of HyLogger data and provides an example of its application to all aspects of resource mining: exploration, extraction and processing, and remediation. In this study, we combine HyLogger-derived scalars indicating Fe-oxide and clay mineralogy with historical geological logs and assay data. In general, background Ni grades (<0.1 wt%) are linked to the presence of montmorillonite + hematite ± goethite, moderate grades (0.1–1.0 wt%) are associated with goethite ± nontronite ± saponite ± kaolinite ± montmorillonite, and higher grades (1.0–2.0 wt%) are coincident with goethite and minimal clay alteration, suggesting that goethite hosts Ni mineralisation. Gibbsite, where it occurs, is found immediately above zones of moderate to high Ni grades and may be an important proximal indicator mineral of nickeliferous laterite. Such a case study serves to suggest opportunities for further data modelling and search and query functionality that could facilitate increased use of this important digital geoscience data resource by the Australian minerals industry for all aspects of resource exploitation: exploration, extraction, processing, and environmental remediation.     

The international outer planets watch atmospheres node database of giant-planet images

The Atmospheres Node of the International Outer Planets Watch (IOPW, formerly known as International Jupiter Watch; Russell et al., 1990) intends to encourage and coordinate the imaging observations and study of the atmospheres of the Giant Planets. The main activity of the atmospheres node is to provide an interaction between the professional and amateur astronomical communities maintaining a large database of images of the giant planets (primarily Jupiter and Saturn but with increasing contributions of Uranus and Neptune too). The observational datasets of Jupiter and Saturn correspond to images obtained in the visible range (300 nm-1 μm), during the last decade, most of them performed by amateur observers. We here describe the organization and structure of the database as posted on the Internet and in particular the PVOL software (Planetary Virtual Observatory Laboratory) designed to manage the site in the spirit of the Virtual Observatory projects. We also describe with examples the important role of the amateur-professional collaboration in the study of the atmospheres of Jupiter and Saturn in an epoch of large telescopes and spacecraft observations of both planets.     

地质找矿改革发展面临的突出问题与对策

国有地勘单位的改革始于20世纪末,以原地矿部所属的地勘队伍以及工业部门所属的大部分地勘单位属地化为标志,国有地勘单位开始了企业化进程。国家一系列优惠政策,给地勘单位的发展注入了新的活力。国家在加大对地勘单位投入的同时,放开了民营资本进入地勘市场的限制,商业性地勘市场出现了前所未有的繁荣,并取得了一大批重要的地质找矿成果。但国民经济的快速发展及国际矿业巨头的垄断,致使国内矿产品供需矛盾日益突出,经济发展对地质技术保障能力的要求被迅速放大,同时地勘单位体制机制的不和谐性也显现出来,具体表现为:勘查体制不顺、找矿机制不活、政策落实不够、勘探能力不强等。针对上述突出问题,提出了完善勘查体制、创新找矿机制、推进政策落实、提升勘探能力等相应的对策。     

中国虚拟天文台可视化服务

虚拟天文台将使天文资料和相关资源的获取更加方便，阐述了可视化对虚拟天文台的必要性和重要性，着重说明了coneSearch界面可视化的内容以及实现方法和开发工具。     

虚拟天文台教育门户建设构想

本文从天文教育的重要性及现状出发，探讨了基于虚拟天文台建设天文教育门户的必要性和可行性；初步设想了结合元数据描述方法，利用虚拟天文台的资源注册和发现机制、元数据记录自动生成机制、元数据集管理机制以及对元数据所标记的资源的查询机制来建设天文教育门户；提供了对我们有借鉴意义的美国教育资源门户网站的运行管理机制；最后对基于虚拟天文台的科学教育的发展前景作了展望。     

基于虚拟天文台的HXMT卫星数据检索发布系统设计与实现

目前,国际上诸多天文项目均遵循虚拟天文台（Virtual Observatory,VO）标准协议开发各天文数据检索发布系统,对外公开发布数据,并对数据资源进行VO注册,从而使用户通过虚拟天文台门户网站即可访问获取不同天文项目的数据集.硬X射线调制望远镜（HXMT）卫星项目也将虚拟天文台技术引入HXMT卫星数据检索发布系统的设计与实现过程中,既满足HXMT卫星数据发布需求,又将HXMT卫星数据融入虚拟天文台环境,实现国际天文数据的共享共用.系统提出了符合虚拟天文台规范的体系架构,并选取SCS锥形检索、VOTable数据格式等虚拟天文台标准协议加以实现,采用MVC模式、SSH框架以及各种J2EE技术进行软件研发,提供检索访问、浏览下载和可视化功能.实践和应用结果表明,系统在解决天文数据资源互操作、共享发布、检索访问及异构应用集成方面均具有可操作性,对我国空间天文卫星数据检索发布系统的研制具有参考意义.     

基于Virtual Globe的地质灾害监测数据集成及可视化

应用Virtual Globe技术和面向服务的软件构架SOA模型.通过综合分析地质灾害的空间数据和业务数据的特点,确定了不同数据类型之间的联系与服务方式.构建了一个地质灾害监测预警三维可视化数据集成框架,实现地质灾害空间数据和业务数据的集成和地质灾害相关信息的三维可视化显示.开发了基于B/S模式的华蓥山地质灾害监测预警...     

街区突发性泄漏的气体扩散过程仿真技术的集成试验

突发性泄漏事故已成为我国城市公共安全的一个潜在威胁.本文以福建省福州市某街区为案例,采用高分辨率遥感影像、各种敏感目标和人口的分布信息等空间数据,利用事件触发机制,建立基础数据库与虚拟现实仿真试验平台.针对威胁城市公共安全的突发性泄漏事故,选择一种适合城市街区尺度的点源气体扩散模型与GIS集成,以构建泄漏气体扩散的三维...