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水印技术作为一项新兴的信息安全技术,在保护矢量地图数据安全中能够发挥重要作用.本文通过分析矢量地图数据特点,研究矢量地图数据数字水印技术特性、常见攻击方式,提出了一种新的多级水印嵌入和检测的算法,嵌入水印时,利用经纬网对矢量地图数据进行划分,综合使用分块嵌入和叠加嵌入的方式,有效提高了水印嵌入级数;检测时,利用相关性原理检测水印信息.实验证明该算法有效可行. 相似文献
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不同类型的矢量地图水印嵌入算法对矢量地图几何特征的影响程度不同,导致含水印矢量地图的可用性遭到不同程度的破坏.针对这一问题,实现了一种现有的保持几何形状的矢量地图水印算法,将其应用于某居民地面矢量数据,并提出了几何形状和坐标精度评价方法,对该水印嵌入算法的普适性和有效性进行分析与评价. 相似文献
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一种鲁棒的矢量地图数据的数字水印 总被引:2,自引:1,他引:1
数字水印是多媒体数据版权保护的一种有效方法。为了将水印技术应用于矢量地图数据的版权保护,根据矢量地图数据各要素层所合数据的多少,设计两种不同的数据分类规则,以实现嵌入不同大小的水印信息。通过仿真实验,可以看出算法具有很好的不可感知性和鲁棒性,尤其是抵抗矢量地图数据最常受到的对数据正常的增加、删除、修改、局部裁剪等更新操作。 相似文献
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矢量地图数据在网络环境下的共享机制,给各个领域都带来了极大的便利,但是其安全和版权保护问题也日益突出。数字水印技术作为版权保护的一种有效方法,成为人们关注的一个焦点。本文分析了矢量地图数据自身特点和常见处理方式;从建立映射关系、构造嵌入域、嵌入方式等3个步骤对空间域水印算法进行了详细分析,分析每种算法的优缺点,为下一步水印算法提供指导;对频率域水印算法进行了研究,并指出了频率域水印算法存在的问题;指出了矢量地图数据水印进一步的研究方向。 相似文献
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《武汉大学学报(信息科学版)》2020,(2)
针对矢量地图数据的完整性认证问题,提出了一种定位篡改实体组的脆弱水印算法。首先将各个地理实体用其最小外接矩形的中点表征,在此基础上采用优化的k均值聚类对地理实体进行分组;然后通过构建实体组的完整性特征参数并结合混沌映射生成脆弱水印;最后将认证信息嵌入到排序处理后的坐标中。水印检测与嵌入过程相对应,通过对比检测出水印和生成水印的一致性,判断实体组是否遭到了篡改。实验结果表明,该算法在有效保持矢量地图数据精度的同时,能够对矢量地图的完整性作出准确认证,具有良好的篡改定位精度。 相似文献
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针对传统矢量地图可逆水印算法往往因片面追求水印容量而容易暴露水印的问题,本文设计了一种扰动程度可控的矢量地图可逆水印算法。首先,基于量化索引调制的思想设计了坐标点的状态区间轴,利用水印信息调制坐标点的状态值实现水印的嵌入;然后,利用最大扰动区域方法限定坐标点状态区间的范围,确保水印信息的嵌入对数据的扰动控制在合理范围内,不会对数据质量造成较大影响;最后,将二进制水印信息十进制化,利用十进制数在最大扰动区域范围内调制坐标点的状态值,实现水印信息的大容量嵌入。试验结果表明,本文提出的矢量地图可逆水印算法不仅容量大,而且扰动程度可控,对常规几何攻击、坐标点攻击等具备较强的稳健性,能够较好地处理水印容量、不可见性及稳健性之间的相互制约关系。 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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Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei OGAWA Edward VERBREE Sisi ZLATANOVA Naohiko KOHTAKE Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118
Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
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地理数据库的关系模型及其实现 总被引:1,自引:0,他引:1
本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4~9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。 相似文献