共查询到20条相似文献，搜索用时 433 毫秒
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传统条件下处理注记与同色符号压盖关系的方法,通常会存在增加数据量、破坏被压盖符号的数据完整性以及操作不灵活等问题。针对这种现象,提出基于GDI+裁剪技术处理注记与同色符号压盖关系的方法。通过计算获取到注记压盖范围内同色符号占据的绘图区域,当绘制被压盖同色符号时,利用GDI+裁剪特性来限制该符号在上述区域内的图形绘制,从而达到"裁剪"注记压盖区域内同色符号的目的。文中方法的整个处理过程完全不需要人工干预就能自动完成,且能够突破过去流水线式的生产作业模式,随机选择不同阶段的编辑内容进行处理,在很大程度上提高了注记与同色符号压盖关系处理的质量和效率。 相似文献
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通过分析地图上各类统计制图符号的图形结构及其图元生成模式,引入统计制图符号布局的概念。在对布局分类及形式化描述的基础上,提出了基于布局的统计制图符号建造模型;设计并实现了统计制图符号快速生成模块,最终应用到统计地图制作过程中。结果表明该模型不仅能快速生成科学美观的单指标统计制图符号,而且还能生成结构复杂的多指标组合统计制图符号,为快速制作多样化统计地图提供了新方法。 相似文献
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《测绘科学技术学报》2013,(6)
地图注记与图形同色压盖关系处理是地图出版编辑的重要内容之一。本文引入了绘图设备的裁剪区原理,建立了注记裁剪区及其分色对应表模型,基于"图层-要素-图元"地图文档结构,实现了一种自动计算注记裁剪区范围并压盖同色线划和填充点符的处理方法。该方法可快速更新裁剪区,快速检索分色对应表,在每次地图绘制过程应用裁剪区。较传统的图形剪断、蒙版等方法,该方法具有不增加地图文档存储数据量,压盖效果好,不限制地图出版编辑工序的特点。 相似文献
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《测绘科学技术学报》2013,(2)
分析现有地图符号构建方法的结构特点及优缺点。从地图符号学研究符号语义表达和图形结构出发,充分利用SVG的描述能力,将地图符号的构建设计为两个部分:SVG结构化描述的语义图元库与符号节点树,提出了基于SVG的地图符号描述模型。该方法丰富符号构建方式,且能够很好地与SVG映射,便于符号共享应用。 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
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Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引：5，自引：0，他引：5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献
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Piyoosh Rautela Ramesh Chandra Lakhera 《International Journal of Applied Earth Observation and Geoinformation》2000,2(3-4)
The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies. 相似文献
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ZHAN F. Benjamin 《地球空间信息科学学报》2011,(1)
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200... 相似文献
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GNSS系统及其技术的发展研究 总被引：3，自引：1，他引：2
阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议. 相似文献
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“4D”技术及其应用 总被引：13，自引：0，他引：13
介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。 相似文献
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《International Journal of Digital Earth》2013,6(1):66-87
Abstract Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised. 相似文献
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自动车辆定位导航系统中传感器的误差分析 总被引：1，自引：0，他引：1
对国界定位导航系统中几种常见的辅助传感器所产生的误差进行了分析，导出了不同传感器的误差模型。这些误差模型是估计车辆位置的扩展卡尔曼滤波器的基础，同时也为选择适当的传感器提供了理论根据。 相似文献