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《测绘科学技术学报》2018,(6)
在对圆形目标进行图像处理以实现精密测量的各种任务中,圆心定位的精度直接决定了测量结果的精度。目前,成熟的圆心定位算法包括重心法、Hough变换法、高斯拟合法、圆拟合法以及椭圆拟合法等。这些常用算法各具优缺点,因此有不同的适用场景。本文提出了一种新的研究思路,利用高斯过程模型解决圆心定位的问题,并且提出了分别基于标准圆和椭圆方程的高斯过程圆心定位算法。实验结果表明,高斯过程标准圆中心定位算法与圆拟合算法的精度相当,而且在残缺圆的圆心定位中抗噪能力更好,精度更高;高斯过程椭圆中心定位算法比椭圆拟合法的抗噪能力更强,精度更高。 相似文献
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对基于空间向量的空间圆拟合算法进行研究,将空间圆看成过球心的空间平面和球壳相交而成的圆,根据球心在空间圆上任意两点连线的中垂面上的性质,利用空间向量组建中垂面方程,与拟合的平面方程联立求解圆心坐标和半径。采用C#语言编写程序进行了算法实现,利用索佳全站仪采集断面数据,使基于该算法的程序在管道准直分析的工程中得到实际应用。 相似文献
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本文提出了水平截面法精细分割树木点云的方法。首先根据点云数据在XOY平面内建立二维格网,求取每个格网内点云数据高度的均值,根据格网内点云数据的高度阈值滤除地面点云和低矮地物点云数据;其次对滤除地面和低矮地物的点云运用八邻域算法提取树木点云,运用水平截面法对树木分层处理,求取每一层树木点云的轮廓线;再次将轮廓线连成多边形,求取多边形的最小外接圆的圆心,运用最小二乘直线拟合算法对各层圆心进行直线拟合,根据拟合直线与地面的交点,可以求取树木的精确位置;最后根据距离最近的原理,对树木进行了精细分割。实验表明:本文研究的方法可以较好的实现树木点云的提取,避免了传统方法设置参数过多的弊端。 相似文献
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全站仪三维坐标法在桥梁施工测量中的应用 总被引:1,自引:0,他引:1
尽管全站仪三维坐标法已在工程测量领域得到广泛采用,但其测量精度及其影响因素还需要深入分析,使之能合理地应用于具体工程。推导了三维坐标的精度计算公式,分析了测量精度的影响因素,针对特定的测量仪器、测量条件和大气折光误差,计算和分析了测点所能达到的精度,阐明了控制和提高测量精度的措施。将该方法应用于苏通大桥墩塔基础施工测量,根据具体的测量仪器和环境条件等,计算测点的点位中误差和高程中误差分别为±5.9mm和±6.9mm,其精度完全满足施工测量的限差要求,表明测量结果具有较高的精度和可信度。 相似文献
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圆曲线的拟合方法与精度分析 总被引:7,自引:0,他引:7
本文给出了测量三点或多点拟合圆的具体公式 ,推出了相应的精度估算式 ,据此研究了拟合圆时测点的最优构形及其对拟合圆的精度影响问题 ,所得结论对实际工作中根据圆周或圆弧段拟合圆心及半径有指导意义 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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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
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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
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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
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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
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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
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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
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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
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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