共查询到20条相似文献，搜索用时 46 毫秒
1.
2.
3.
针对RTCM委员会推出的GNSS差分数据传输格式RTCM 10403.2,该文介绍了其电文特点,并着重分析了其内部循环算法和CRC校验算法。RTMC 3.2格式相比之前版本增加了MSM电文组,在数据格式上最大的特点是采用了内部循环,并首次支持了北斗卫星导航系统。针对这些特点,文章设计了编解码算法,编写软件予以实现并对编码算法和解码算法分别进行实验。实验结果表明:所设计的编解码算法及编写的软件能够正确,并可靠地处理RTCM 3.2数据格式,可以在实际的GNSS差分定位中进行应用。 相似文献
4.
5.
在全球卫星导航系统的研究和测量工作中,需要对GNSS测量数据进行分析和计算,解码GPS接收机原始数据是实时获得以上数据的主要方法。原始电文的二进制格式由各接收机板卡厂商及板卡集成厂家定义本文介绍了常用原始GNSS数据格式内容并对其进行解码转化为标准的RINEX格式文件。该解码软件可以对多种数据格式的电文进行分析解码得到相应的多系统观测文件和星历文件,包括BDS三频数据,并可以根据需要选择生成的RINEX文件中系统类型。使用TEQC软件对数据质量进行进一步的质量分析,为后续的数据分析和处理提供了可靠的保障。 相似文献
6.
DGNSS差分电文解码算法研究 总被引：1，自引：1，他引：0
DGNSS是提高GNSS系统定位精度的有效途径。本文在分析DGNSS电文格式的基础上,提出针对本格式电文的完整解码算法,并采用C++编程语言进行实现;通过对实际数据的解码测试,验证了解码算法的正确性。 相似文献
7.
随着互联网技术的发展,利用互联网将观测站的实时GNSS数据高速传输给数据处理中心,可以打破GNSS数据事后处理的传统模式,从而实现GNSS数据的实时处理。对于数据处理中心而言,具备实时GNSS数据流管理功能的软件平台就显得尤为重要。本文主要对自主实现的实时GNSS数据流管理平台软件的实现及应用进行了介绍。该软件采用C/S框架设计,实现后端服务与前端用户界面相分离的效果,可通过网络与观测站建立连接来获取实时GNSS数据流,支持TCP/IP通信协议及NTRIP通信协议,支持解码RTCM3.X、BINEX等多种数据传输格式,能够汇聚分布在各地的观测站的GNSS数据,为后续的数据实时处理工作提供数据支撑,并在我国所发起的国际GNSS监测评估系统建设中得到应用。 相似文献
8.
通过分析虚拟参考站技术和主辅站技术的不足,提出了一种新的网络RTK技术——增强参考站技术(ARS).分析了这种技术的原理并阐述了该技术中改正数的生成方法,同时,提出了一种基于RTCM编码的适合于该技术的改正数编码格式.在此基础上,分析了该技术的RTK定位精度、数据传输效率和系统可靠性,从理论上说明了增强参考站的技术优势.最后,以四川综合GPS服务网(SIGN)的子网数据对该技术进行了验证,结果表明,该技术具有高定位精度、高数据传输效率的特点,是一种理想的网络RTK技术. 相似文献
9.
RTK技术具有实时高效等特点,使其在测量与导航领域得以广泛应用。传统的RTK数据传输模式为电台数传链路,其时空局限性的特点制约了RTK技术应用的进一步发展。随着Internet网络应用的蓬勃发展,GPS差分定位与RTK定位测量模式也相应产生巨大的变革,网络技术为GPSRTK技术提供了新的突破点:结合Inter-net技术来进行GPS高精度实时动态定位。本文通过分析TCP/IP和UDP两种Internet传输协议、GPS差分数据RTCM类型和字节大小,及其在两种网络协议下数据传输速度的比较,对应用Internet作为差分GPS数据传输方式进行测试与分析。 相似文献
10.
11.
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
12.
SVG是一种基于XML的用来描述二维矢量图形和矢量/栅格混合图形的标记语言,虽然SVG不是为了面向地理空间数据发布而制定的标准,但它的许多特性都能被广泛地应用到WebGIS中,从而实现矢量WebGIS。由于SVG通过简单的文本语句描述矢量图像,所以SVG通常数据量很小,并且SVG支持GZIP压缩,所以基于SVG构建WebGIS能减轻网络传输负载,加快地图显示速度。SVG内置了对JavaScript的支持,且SVG可通过DOM解析映像成内存中的树型结构,所以客户层可通过JavaScript对DOM的操作实现对地图的缩放、漫游、查询、图层控制等交互操作。 相似文献
13.
本文在讨论DDE技术的基础上，对MapInfo的DDE机制的实现作了探讨和分析。根据技园区域GIS的实际开发工作，介绍了利用DDE技术在MapInfo中成功地集成Foxpro和Autocad. 相似文献
14.
遥感技术在土地利用动态监测中的应用 总被引：8，自引：0，他引：8
金时华 《测绘与空间地理信息》2006,29(1):98-101
主要论述遥感技术在土地监测中的应用,以某地区土地利用动态遥感监测研究项目的运作过程为例进行阐述。首先介绍了土地利用动态监测的具体内容和技术路线。其次,对数据预处理与信息采集的方法与手段进行了探讨。最后,对作业的内、外业主要过程以及应提交的成果作了介绍。 相似文献
15.
16.
Automatic 3D extraction of building roofs from remotely sensed data is important for many applications including city modelling. This paper proposes a new method for automatic 3D roof extraction through an effective integration of LIDAR (Light Detection And Ranging) data and multispectral orthoimagery. Using the ground height from a DEM (Digital Elevation Model), the raw LIDAR points are separated into two groups. The first group contains the ground points that are exploited to constitute a ‘ground mask’. The second group contains the non-ground points which are segmented using an innovative image line guided segmentation technique to extract the roof planes. The image lines are extracted from the grey-scale version of the orthoimage and then classified into several classes such as ‘ground’, ‘tree’, ‘roof edge’ and ‘roof ridge’ using the ground mask and colour and texture information from the orthoimagery. During segmentation of the non-ground LIDAR points, the lines from the latter two classes are used as baselines to locate the nearby LIDAR points of the neighbouring planes. For each plane a robust seed region is thereby defined using the nearby non-ground LIDAR points of a baseline and this region is iteratively grown to extract the complete roof plane. Finally, a newly proposed rule-based procedure is applied to remove planes constructed on trees. Experimental results show that the proposed method can successfully remove vegetation and so offers high extraction rates. 相似文献
17.
遥感和GIS技术应用于伊拉克南部Basrah省土地利用/覆盖变化及城市扩张研究(英文) 总被引：2，自引：0，他引：2
In recent years, land use/cover dynamic change has become a key subject that needs to be dealt with in the study of global
environmental change. In this paper, remote sensing and geographic information systems (GIS) are integrated to monitor, map,
and quantify the land use/cover change in the southern part of Iraq (Basrah Province was taken as a case) by using a 1:250
000 mapping scale. Remote sensing and GIS software were used to classify Landsat TM in 1990 and Landsat ETM+ in 2003 imagery
into five land use and land cover (LULC) classes: vegetation, sand, urban area, unused land, and water bodies. Supervised
classification and normalized difference build-up index (NDBI) were used respectively to retrieve its urban boundary. An accuracy
assessment was performed on the 2003 LULC map to determine the reliability of the map. Finally, GIS software was used to quantify
and illustrate the various LULC conversions that took place over the 13-year span of time. Results showed that the urban area
had increased by the rate of 1.2% per year, with area expansion from 3 299.1 km2 in 1990 to 3 794.9 km2 in 2003. Large vegetation area in the north and southeast were converted into urban construction land. The land use/cover
changes of Basrah Province were mainly caused by rapid development of the urban economy and population immigration from the
countryside. In addition, the former government policy of “returning farmland to transportation and huge expansion in military
camps” was the major driving force for vegetation land change. The paper concludes that remote sensing and GIS can be used
to create LULC maps. It also notes that the maps generated can be used to delineate the changes that take place over time.
Supported by the Al-Basrah University, Iraq, the Geo-information Science and Technology Program (No. IRT 0438)China). 相似文献
18.
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
19.
随着城市面貌日新月异,地下管网的建设也在持续推进,作为城市的地下“神经网络”,全天24 h保障城市的正常运转和发展。本文以实现城市管网管理系统的高可用、无插件、智能化为目标,采用“地上地下一体”“二三维一体”的设计理念,研究基于WebGL的三维智慧管网系统的关键技术,实现了管线设施管理的信息数字化、空间化与图形化。 相似文献
20.
We aim a better understanding of the effect of spring-time snow melt on the remotely sensed scene reflectance by using an extensive amount of optical spectral data obtained from an airborne hyperspectral campaign in Northern Finland. We investigate the behaviour of thin snow reflectance for different land cover types, such as open areas, boreal forests and treeless fells. Our results not only confirm the generally known fact that the reflectance of a melting thin snow layer is considerably lower than that of a thick snow layer, but we also present analyses of the reflectance variation over different land covers and in boreal forests as a function of canopy coverage. According to common knowledge, the highly variating reflectance spectra of partially transparent, most likely also contaminated thin snow pack weakens the performance of snow detection algorithms, in particular in the mapping of Fractional Snow Cover (FSC) during the end of the melting period. The obtained results directly support further development of the SCAmod algorithm for FSC retrieval, and can be likewise applied to develop other algorithms for optical satellite data (e.g. spectral unmixing methods), and to perform accuracy assessments for snow detection algorithms.A useful part of this work is the investigation of the competence of Normalized Difference Snow Index (NDSI) in snow detection in late spring, since it is widely used in snow mapping. We conclude, based on the spectral data analysis, that the NDSI -based snow mapping is more accurate in open areas than in forests. However, at the very end of the snow melting period the behavior of the NDSI becomes more unstable and unpredictable in non-forests with shallow snow, increasing the inaccuracy also in non-forested areas. For instance in peatbogs covered by melting snow layer (snow depth < 30 cm) the mean NDSI -0.6 was observed, having coefficient of variation as high as 70%, whereas for deeper snow packs the mean NDSI shows positive values. 相似文献