Multi-resolution seamless image database

This paper presents the basic concepts and principles, data structure and high efficient spatial index for multi-resolution image database. The database is characterized by arrangement of multi-resource image data and seamless mosaic, distribution-based storage and management, integration with other spatial database software such as GeoStar and GeoGrid developed by Wuhan Technical University of Surveying and Mapping.     

Verification of net primary production estimation method in the Mongolian Plateau using landsat ETM+data

We plan to estimate global net primary production (NPP) of vegetation using the Advanced Earth Observing Satellite-II (ADEOS-II) Global Imager (GLI) multi-spectral data. We derive an NPP estimation algorithm from ground measurement data on temperate plants in Japan. By the algorithm, we estimate NPP using a vegetation index based on pattern decomposition (VIPD) for the Mongolian Plateau. The VIPD is derived from Landsat ETM+multi-spectral data, and the resulting NPP estimation is compared with ground data measured in a semi-arid area of Mongolia. The NPP estimation derived from satellite remote sensing data agrees with the ground measurement data within the error range of 15% when all above-ground vegetation NPP is calculated for different vegetation classifications.     

A 3-dimensional data model for visualizing cloverleaf junction in a city model

The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its main body is bestraddle in air, and has aerial intersections between its parts. This complex feature made cloverleaf junction quite different from buildings and terrain, therefore, it is difficult to express this kind of spatial objects in the same way as for buildings and terrain. In this paper, authors analyze spatial characteristics of cloverleaf junction, propose an all-constraint points TIN algorithm to partition cloverleaf junction road surface, and develop a method to visualize cloverleaf junction road, surface using TIN. In order to manage cloverleaf junction data efficiently, the authors also analyzed the mechanism of 3DCM data management, extended BLOB type in relational database, and combined R-tree index to manage 3D spatial data. Based on this extension, an appropriate data structure for cloverleaf junction in 3DCM is proposed.     

Using SPOT 5 fusion-ready imagery to detect Chinese tamarisk (saltcedar) with mathematical morphological method

Chinese tamarisk (saltcedar) is a deciduous shrub that occurs widely across the Yellow River Delta in China. The spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rare birds. In this study, first, Chinese tamarisk is detected using Canny edge detector and mathematical morphological operators based on SPOT 5 fusion-ready imagery. Then the numbers, areas, locations, and patch spacing of Chinese tamarisk patches are calculated. The experiments show that the detection accuracy of Chinese tamarisk patches is about 93.4% after the disconnection of connected patches. The distribution orientation of about 70% of the patches is approximately south–north. About 91% of the minimum distances among the patches are between 12.5 and 57.5 m. The rose graph indicates that the main azimuth between patches is north–northwest, and the second is northeast and southeast. The present study indicates that the integrating Canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting Chinese tamarisk patches and is easy to identify the spatial structure of Chinese tamarisk patches, which reduces the time and labor for the visual interpretation of Chinese tamarisk patches.     

利用轨迹大数据进行城市道路交叉口识别及结构提取

交叉口是城市交通路网生成、更新的重要组成部分。本文基于车辆时空轨迹大数据,提出了一种城市交叉口自动识别方法。该方法首先通过轨迹跟踪识别轨迹数据中包含的车辆转向点对;然后基于距离和角度的生长聚类方法进行转向点对的空间聚类,并采用基于局部点连通性的聚类方法识别交叉口;最后利用交叉口范围圆和转向点对提取城市各级别路网下的交叉口结构。以武汉市出租车轨迹大数据为例,对武汉市城区内189个交叉口进行了探测。试验结果表明,本文所提方法可以准确地从轨迹大数据中识别出城市交叉口及其结构。     

引潮位的Doodson规格化展开及其精度评定

基于引潮位Doodson规格化展开的基本原理以及ELP/MPP02月球历表、Newcomb太阳历表的结构,设计了一个用以代表三角函数的数据结构;并由此自定义了三角函数的乘法与加法算法,将月球、太阳引潮位分别展开至5阶、3阶,振幅绝对值截断阈值为10-7,在展开过程中对"伪波"进行"滤波"处理后,最终得到包含4 686项展开式的引潮位展开表(其中振幅绝对值超过10-6的展开式有2 441项)。以德国BFO(Black Forest Observatory)测站为例,基于DE431历表,通过天球参考系变换计算得到1950—2050年间时间间隔为1 h的法向引潮力基准序列BFDE431;并根据各个引潮位展开表计算得到相应的法向引潮力序列;通过与BFDE431基准序列求差,得到各个差值序列的统计值。计算结果表明,文中给出的展开表对应的差值序列数值在±58×10~(-11)m·s~(-2)(nGal)以内,均方差为12.5×10~(-11)m·s~(-2),与XI89展开表的精度相当。但由于没有考虑行星及地球扁率的影响,仍未达到HW95和RATGP95展开表的精度水平。     

地理要素的分布式空间近似查询处理方法

针对传统空间查询无法满足地理数据交互式可视化对处理时间要求的问题,以窗口查询为例,提出了一种空间近似查询处理方法。该方法包括预处理和查询两步:在预处理阶段,利用分布化的线简化算法对空间对象进行顾及误差的预处理采样,将采样过程及误差值用树型结构保存;在查询阶段,以豪斯多夫距离定义数据可视化的误差,进行误差可知的顶点即时采样与截取,从而实现针对可视化应用的高效的空间近似查询处理。在Hadoop集群上利用77GB的OpenStreetMap数据集进行了实验,证实了本方法的效力与效率。     

基于GIS的兰州市主城区牛肉面馆空间分布特征及趋向性分析

研究兰州市主城区牛肉面馆空间分布特征及趋向性,对今后兰州市城市规划、牛肉面行业投资等有重要的指导意义。本文基于GeoSharp V1.0提取的牛肉面馆和学校的点数据和兰州市主城区路网数据,运用核密度和缓冲区分析方法,研究牛肉面馆空间分布特征及趋向性。研究结果表明:从空间分布来看,兰州市牛肉面馆整体的分布格局呈现中心-外围结构,即中心城区为高聚集区,向外依次呈梯度递减的圈层状空间格局,对牛肉面馆与学校、道路的空间趋向性研究发现,牛肉面馆的分布对学校、道路有较强的趋向性。研究结果以期为兰州市主城区牛肉面产业发展提出决策建议、改善投资环境等提供科学依据。     

Delaunay三角网关键技术探讨

利用计算机技术,基于实际测量数据,利用逐点插入法,在不建立格网索引的情况下,提出一种高效的Delaunay三角网构建方法,与建立格网索引法搜索点所在的三角形相比,具有较高的执行效率.     

结构保持的图像序列自适应超分辨率重建

基于概率运动估计的超分辨算法能克服传统超分辨率方法过分依赖于准确运动估计的缺点,为了改善其重建效果,通过分析图像的局部结构模式,给出了局部空域活跃度的定义表征图像的局部结构特征,设计了形状、尺度自适应的非局部空时邻域窗口函数,进而提出了一种结构保持的超分辨率自适应重建算法。实验结果显示,本文方法具有更好的重建性能。