一种提高精密单点定位实时性的方法

由于要获取PPP需要的精密钟差文件至少有2d的时间延迟,因此通过提取IGS当天发布的超快星历中的卫星钟差数据,并对钟差数据进行插值,将插值结果做成标准格式钟差数据文件应用到PPP中,可以将精密单点定位的实时性提高为3~9h。基于Bernese软件,采用生成的钟差文件以及当天的超快星历文件对大量实测数据进行PPP。结果表明,对于4h的观测数据,该方法解算精度达到厘米级;当观测时间大于6h时,解算精度基本能够稳定在1~5cm。     

Algorithm for generating dem based on cone

Digital elevation model (DEM) has a variety of applications in GIS and CAD. It is the basic model for generating three-dimensional terrain feature. Generally speaking, there are two methods for building DEM. One is based upon the digital terrain model of discrete points, and is characterized by fast speed and low precision. The other is based upon triangular digital terrain model, and slow speed and high precision are the features of the method. Combining the advantages of the two methods, an algorithm for generating DEM with discrete points is presented in this paper. When interpolating elevation, this method can create a triangle which includes interpolating point and the elevation of the interpolating point can be obtained from the traingle. The method has the advantage of fast speed, high precision and less memory.     

面雨量空间扩展估算法

以温州地区1991～2001年90个观测站的月平均降雨为例,在GIS支持下,对样条函数法、克立格内插法及距离平方反比法这3种插值方法进行了对比研究;并在90个观测站中筛选出最少量的、能达到稳定结果的站点数;还考虑了插值的空间分辨率对结果的影响。对上述3点进行大量的计算、统计分析的结果表明:①在选择距离平方反比法及样条函数法对月平均降雨量插值效果均较好;②利用这两种插值方法对不同站点密度选取不同空间分辨率插值后得出,选取50站误差趋于稳定,利用距离平方反比法插值结果误差较小,而空间分辨率对结果几乎没有影响。利用距离平方反比法,选择50个站得到了温州地区1km×1km面雨量空间扩展结果,为水文预报工作提供一种较精确的面雨量估算和输入方法。     

Algorithm for generating dem based on cone

Digital elevation model (DEM) has a variety of applications in GIS and CAD.It is the basic model for generating three-dimensional terrain feature.Generally speaking,there are two methods for building DEM.One is based upon the digital terrain model of discrete points,and is characterized by fast speed and low precision.The other is based upon triangular digital terrain model,and slow speed and high precision are the features of the method.Combining the advantages of the two methods,an algorithm for generating DEM with discrete points is presented in this paper.When interpolating elevation,this method can create a triangle which includes interpolating point and the elevation of the interpolating point can be obtained from the triangle.The method has the advantage of fast speed,high precision and less memory.     

三维地质建模中虚拟钻孔的引入及其确定

三维地质建模中由于地质数据缺乏导致模型难以控制三维形体边界特征,直接影响到模型的实用价值.针对这一问题,文章引入了虚拟钻孔,用于增加数据点密度,有效控制三维形体边界.以地层受断层破坏为例,分别就地层与断层4种典型空间分布组合特征下虚拟钻孔的确定方法进行了研究,提出了相应解决方案.由于虚拟钻孔具有普通钻孔的性质,在数据存储方式、数据结构和表达方式等方面具有一致性,可以加快三维地质建模,提高建模精度.     

利用锥构建DEM生成算法的研究

在综合基于离散点数模和三角网数模生成DEM两种方法优点的基础上 ,提出了一种基于离散无序点的快速生成DEM的方法。该方法有内插速度快、精度高及占用内存小的优点。