An Improved Hilbert Curve for Parallel Spatial Data Partitioning

A novel Hilbert-curve is introduced for parallel spatial data partitioning, with consideration of the huge-amount property of spatial information and the variable-length characteristic of vector data i...     

Imaging spectroscopy in soil-water based site suitability assessment for artificial regeneration to Scots pine

In a humid northern boreal climate, the success rate of artificial regeneration to Scots pine (Pinus sylvestris L.) can be improved by including a soil water content (SWC) based assessment of site suitability in the reforestation planning process. This paper introduces an application of airborne visible-near-infrared imaging spectroscopic data to identify suitable subregions of forest compartments for the low SWC-tolerant Scots pine. The spatial patterns of understorey plant species communities, recorded by the AISA (Airborne Imaging Spectrometer for Applications) sensor, were demonstrated to be dependant on the underlying SWC. According to the nonmetric multidimensional scaling and correlation results twelve understorey species were found to be most abundant on sites with high soil SWCs. The abundance of bare soil, rocks and abundance of more than ten species indicated low soil SWCs. The spatial patterns of understorey are attributed to time-stability of the underlying SWC patterns. A supervised artificial neural network (radial basis functional link network, probabilistic neural network) approach was taken to classify AISA imaging spectrometer data with dielectric (as a measure volumetric SWC) ground referencing into regimes suitable and unsuitable for Scots pine. The accuracy assessment with receiver operating characteristics curves demonstrated a maximum of 74.1% area under the curve values which indicated moderate success of the NN modelling. The results signified the importance of the training set’s quality, adequate quantity (>2.43 points/ha) and NN algorithm selection over the NN algorithm training parameter optimization to perfection. This methodology for the analysis of site suitability of Scots pine can be recommended, especially when artificial regeneration of former mixed wood Norway spruce (Picea abies L. Karst) - downy birch (Betula pubenscens Ehrh.) stands is being considered, so that artificially regenerated areas to Scots pine can be optimized for forestry purposes.     

非对称缓和曲线坐标计算方法

本文重点阐述高等级公路非标准缓和曲线的施工放样测量.缓和曲线是设置在直线和圆曲线之间的一种线型,起缓和过渡作用,其目的在于保证车辆由直线进入圆曲线(或由圆曲线进入直线)时的横向稳定,缓和曲线的曲率半径随曲线长度的增加而均匀连续地变小,本文综合了各种情况下的曲线计算,给出了直接计算和间接计算两种计算方法,并用C编写了计算...     

基于最小二乘法道路平面曲线拟合

结合最小二乘法的基本原理,利用其进行道路平面曲线拟合,实例表明,与三次样条函数设计计算结果接近,同样能满足路线设计要求,且简化了计算过程,在平面设计工作中具有很强的实用性。     

实时动态差分法测量精度模型及实验研究

从实时动态差分（RTK）测量精度的表现结果出发,通过综合分析RTK测量误差特性,推导出反映RTK测量精度的数学模型,并用实例验证。为实时预测评价RTK局域性控制测量提供可行依据,切实指导RTK测量实践,具有较好借鉴价值。     

GIS中曲线综合平差模型的建立

针对大中比例尺地图中的行政界线、地块权属界线的制图综合问题,利用Douglas Peuker算法,提出距离阈值自适应求解算法对图形进行综合;将平差理论应用于综合后图形的处理中,保证图形的综合质量。讨论了面积、长度、固定点、直角/直线条件的建立,结合实例,研究了综合、平差的算法框架与实施步骤。     

GIS中3维空间圆曲线的不确定性εσ模型

随着GIS向3维领域的不断发展,对3维空间元素的不确定性研究日趋重要.基于不确定性理论及概率统计理论,研究GIS中3维空间圆曲线的不确定性模型.首先建立3维空间圆曲线上任意点坐标的微分关系式,然后得到圆曲线上任意点坐标的方差, 进而获得3维空间圆曲线的εσ模型.实际算例表明,3维空间圆曲线误差分布呈现出"两端大,中间小"的趋势.     

变形曲线的SVM分类及在变形等级划分中的应用

变形等级的划分对信息化施工和及时采取相应针对性防治措施以及地震形变在线式分析和预警系统的研究中具有重要的理论与实践意义.本文提出以曲线的曲率和二阶导数来描述变形曲线的特征,并作为SVM输入量对变形进行自动多类分类.     

指数曲线模型预测基坑周边地面沉降

结合天津富裕广场三期工程基坑周围地面沉降观测的工作实践,利用指数曲线法对该工程的地面沉降过程进行了预测,得出实际观测值与预测值之间的拟合曲线,并通过比较得出该预测方法的优劣。     

数字原稿色域的定量分析与比较

提出了一种科学、准确地定量分析数字原稿色域的方法,通过相关实验比较了各种成像环境对数字原稿色域的影响,并获得了一些有价值的成果。