顾及语义的室内三维模型数据组织与可视化     

朱泽洲  熊汉江  戴雪峰 《测绘与空间地理信息》2015,(4)

本文提出了一种顾及语义的"实体-区域-入口"数据组织机制,有效整合了现有的城市三维地理空间数据与建筑物室内精细模型数据,实现了高效的室内场景数据调度与可视化;并基于此构建了三维可视化系统,验证了该方法的有效性和可行性。  相似文献   

基于语义网的地名本体服务框架研究     

梁汝鹏  李文娟  李勤超  姜海林 《测绘科学》2011,36(3):230-233

本文在总结地名本体的基本概念基础上,根据基于地理空间语义网的日常地理信息查询需要,进行了地名本体的概念设计.地名本体的设计可以分为两个阶段,第一阶段主要偏重于初级本体的设计,它主要支持地理对象的标示和检索等较为初级的任务.第二阶段将支持更多高级的任务,例如空间推理等.本文通过地名本体模型的构建,探讨了基于语义网的地名本...  相似文献   

Terrestrial laser scanning to estimate plot-level forest canopy fuel properties     

Mariano García  F. Mark Danson  David Riaño  Emilio Chuvieco  F. Alberto Ramirez  Vishal Bandugula 《International Journal of Applied Earth Observation and Geoinformation》2011

This paper evaluates the potential of a terrestrial laser scanner (TLS) to characterize forest canopy fuel characteristics at plot level. Several canopy properties, namely canopy height, canopy cover, canopy base height and fuel strata gap were estimated. Different approaches were tested to avoid the effect of canopy shadowing on canopy height estimation caused by deployment of the TLS below the canopy. Estimation of canopy height using a grid approach provided a coefficient of determination of R² = 0.81 and an RMSE of 2.47 m. A similar RMSE was obtained using the 99th percentile of the height distribution of the highest points, representing the 1% of the data, although the coefficient of determination was lower (R² = 0.70). Canopy cover (CC) was estimated as a function of the occupied cells of a grid superimposed upon the TLS point clouds. It was found that CC estimates were dependent on the cell size selected, with 3 cm being the optimum resolution for this study. The effect of the zenith view angle on CC estimates was also analyzed. A simple method was developed to estimate canopy base height from the vegetation vertical profiles derived from an occupied/non-occupied voxels approach. Canopy base height was estimated with an RMSE of 3.09 m and an R² = 0.86. Terrestrial laser scanning also provides a unique opportunity to estimate the fuel strata gap (FSG), which has not been previously derived from remotely sensed data. The FSG was also derived from the vegetation vertical profile with an RMSE of 1.53 m and an R² = 0.87.  相似文献   

2010年2月27日智利Mw8.8地震前全球地震活动特征分析          下载免费PDF全文

薛艳  刘杰  李纲 《地震学报》2011,33(3):292-303

通过对智利地震前全球不同时空范围地震活动特征分析,发现:①智利地震前出现了两类地震空区:第一类空区为1900年以来形成的360 km长的Mw≥8.0地震空段,第二类空区为震前5年形成的780 km长的M≥5.5地震空段;②1986-2010年,智利中南部仅发生1次Mw7.1地震,表现为显著的Mw≥7.0地震平静异常;③...  相似文献   

太康4．7级地震前地震活动图像和趋势分析     

林眉  刘希强  郑建常  徐长朋  冀东普 《地震地磁观测与研究》2011,32(4):7-11

对苏、鲁、皖、豫交界地区地震活动进行研究,指出该区2006年10月-2010年10月出现一个长轴约230km的3级地震空区。该空区及附近地区存在多项中期异常,即ML≥3地震活动具有频度高、能量强,中等地震震中空间分布相对集中及低b值等。讨论认为,苏、鲁、皖、豫交界地区存在多项中期异常,与2004年10月24日太康4．7级地震的强度不匹配,未来具有发生中强以上地震的危险。  相似文献   

地质灾害领域本体的研究与应用     

王艳妮  刘刚 《地理与地理信息科学》2011,27(6)

引入了由斯坦福大学医学院开发的七步法,并采用OWL DL语言描述本体,利用目前成熟的且流行的本体可视化构建工具Protégé完成地质灾害信息领域本体库的构建。基于行业标准、地质灾害信息处理标准、专家知识等相关标准,建立地质灾害领域本体。用OWL形式化描述基于多层结构的地质灾害空间数据本体应用模型来实现三层地质灾害本体。以具有优势的三峡库区丰富地质灾害资料为依托,以地质灾害多源异构空间信息集成与共享为主线,引入本体理论和GeoSciML,研究建立基于顶级、领域及应用多层本体的地质灾害空间数据语义集成和共享模型,实现地质灾害信息系统数据集成和应用集成,目标是解决横向各部门间的有效沟通和信息共享,以及单体灾害和群体灾害发生时的应急指挥和决策支持等问题。  相似文献   

一种胶体光子晶体修饰的光纤     

刘青  王鸣  郭文华  闫海涛  喻平 《海洋学报》2010,32(10):7086-7090

设计了一种胶体光子晶体修饰的光纤. 采用恒温快速蒸发法直接在经切割刀处理后的光纤端面生长胶体晶体,再与另一根切割后的光纤在毛细玻璃管中完成对接,制备成胶体光子晶体修饰的光纤. 用扫描电子显微镜和光谱分析仪对样品的形貌、结构以及光学特性进行分析. 实验结果表明,粒径为640 nm、体积分数约为0.5%的SiO₂胶体微球溶液在60 ℃的情况下沉积,大约12 h后可得到质量较高的胶体光子晶体. 在SEM下,观察到端面的胶体晶体为面心立方(fcc)结构. 透射光谱证明,该结构在(111)面上  相似文献   

Numerical study of an oscillating smaller cylinder in the wake of an upstream larger cylinder     

TAN Soon Keat 《中国海洋大学学报(英文版)》2012,11(2):111-117

A numerical study of flow around two tandem cylinders with unequal diameters was carried out. The upstream larger cylinder was fixed and the downstream smaller cylinder was allowed to oscillate in the transverse direction only. Comparisons of the experimental and numerical results were made to investigate the effects of the gap ratio on the maximum vibration amplitude and vortex shedding frequency. The results showed that the vibration response of the smaller cylinder was significantly affected by the presence of the upstream larger cylinder, and resulted in greatly reduced vibration amplitudes. With an increasing gap ratio, the vibration amplitude increased. However, the magnitude was lower than that corresponding to a single cylinder (with the same diameter as that of the downstream smaller cylinder) under the same flow conditions.  相似文献   

Effects of different gap filling methods and land surface energy balance closure on annual net ecosystem exchange in a semiarid area of China     

DU Qun  LIU HuiZhi  FENG JianWu  WANG Lei 《中国科学:地球科学(英文版)》2014,57(6):1340-1351

Based on eddy covariance measurements over two kinds of land surfaces(a degraded grassland and a maize cropland)in a semiarid area of China in 2005 and 2008,the effects of different gap filling methods,energy balance closure and friction velocity threshold(u*)on annual net ecosystem exchange(NEE)were analyzed.Six gap filling methods,including mean diurnal variation(MDV),marginal distribution sampling(MDS),and nonlinear regressions method,were investigated by generating secondary datasets with four different artificial gap lengths(ranging in length from single half-hours to 12 consecutive days).The MDS generally showed a good overall performance especially for long gaps,with an annual sum bias error less than 5 g C m-2 yr-1.There was a large positive annual sum bias error for nonlinear regressions,indicating an overestimate on net ecosystem respiration.The offset in the annual sum NEE for four nonlinear regressions was from 8.0 to 30.8 g C m-2 yr-1.As soil water content was a limiting factor in the semiarid area,the nonlinear regressions considering both soil temperature and soil water content as controlling variables had a better performance than others.The performance of MDV was better in daytime than in nighttime,with an annual sum bias error falling between-2.6 and-13.4 g C m-2 yr-1.Overall,the accuracy of the gap filling method was dependent on the type of the land surface,gap length,and the time of day when the data gap occurred.The energy balance ratio for the two ecosystems was nearly 80%.Turbulent intensity had a large impact on energy balance ratio.Low energy balance ratio was observed under low friction velocity during the night.When there was a large fetch distance in a wind direction,a low energy balance ratio was caused by mismatch of the footprints between the available energy and turbulent fluxes.The effect of energy balance correction on CO2 flux was evaluated by assuming the imbalance caused by the underestimation of sensible heat flux and latent heat flux.The results showed an average increase of 10 g C m-2 yr-1 for annual NEE in both ecosystems with an energy balance correction.On the other hand,the u*threshold also have a large impact on annual sum NEE.Net carbon emission increased 37.5 g C m-2 yr-1 as u*threshold increased from 0.1 to 0.2 m s-1,indicating a large impact of imposing u*threshold on net ecosystem carbon exchange.  相似文献   

语义驱动的层次化地图符号设计方法     

田江鹏  贾奋励  夏青  吴金兵 《地球信息科学学报》2012,14(6):736-743

地图符号是地图学的重要组成部分。当前有关地图符号的研究,主体均集中在地图符号的视觉图形方面,而对地图符号的概念语义缺乏足够的重视。本文提出了一种语义驱动的层次化地图符号设计方法,即以语义关系作为符号图形构造的基准,通过语义关系控制地图符号的图形构成,以充分发掘地图符号的概念语义成分在符号设计中的内在价值。重点论述了本体层次的语义特征提取、符素设计、聚合语义结构建模和语义驱动的符号生成4个关键步骤。利用本文符号设计方法对现有符号标准进行改进设计和认知实验。结果表明,该方法在符号认识效率方面表现较优,且在模拟信息传输过程中体现了较为稳定的高传输效率,具备有效提升地图符号的信息感知效率的潜力。  相似文献