共查询到20条相似文献，搜索用时 375 毫秒
1.
DEM Compression Based on Integer Wavelet Transform 总被引：1，自引：0，他引：1
CHEN Renxi LI Xinhui 《地球空间信息科学学报》2007,10(2):133-136
DEM data is an important component of spatial database in GIS. The data volume is so huge that compression is necessary. Wavelet transform has many advantages and has become a trend in data compression. Considering the simplicity and high efficiency of the compression system, integer wavelet transform is applied to DEM and a simple coding algorithm with high efficiency is introduced. Experiments on a variety of DEM are carried out and some useful rules are presented at the end of this paper. 相似文献
2.
SUGuozhong YANLi LIUNan LIURenyi 《地球空间信息科学学报》2004,7(3):180-186
A practical method for visualizing flood area and evaluating damage is presented, which consists of two technical approaches: self-programming and adapting commercial GIS platforms. The low-cost and easy-to-use GIS-Based model developed by self-programming can meet current requirements of most local authorities, especially in developing countries. In this model, two cases, non-source flood and source flood, are distinguished and the Seed-spread algorithm suitable for source-flood is discussed; The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data. and all the-matic maps are converted to raster format before overlay analysis. Two measures are taken to improve the operation efficiency of speed seed-spread algorithm. The accuracy of the model mainly depends on the resolution and precision of the DEM data, and the accuracy of registering all raster layers and the quality of attribute data. 相似文献
3.
WANGZhenjie OUJikun LIUGenyou RENChao 《地球空间信息科学学报》2004,7(4):284-289
A new algorithm, called as Double-Epoch Algorithm (DEA) is proposed in GPS rapid positioning using two epoch single frequency phase data in this paper. Firstly, the structure characteristic of the normal matrix in GPS rapid positioning is analyzed. Then, in the light of the characteristic, based on TIKHONOV regularization theorem, a new regularizer is designed to mitigate the ill-condition of the normal matrix. The accurate float ambiguity solutions and their MSEM (Mean Squared Error Matrix) are obtained, using two epoch single frequency phase data. Combined with LAMBDA method, DEA can fix the integer ambiguities correctly and quickly using MSEM instead of the covariance matrix of the ambiguities. Compared with the traditional methods, DEA can improve the efficiency obviously in rapid positioning. So, the new algorithm has an extensive application outlook in deformation monitoring, pseudokinematic relative positioning and attitude determination, etc. 相似文献
4.
The capability of humancomputer interaction reflects the intelligent degree of mobile navigation system.The navigation data and functions of mobile navigation system are divided into system commands and non-system commands in this paper,And then a group of speech commands are abstracted.This paper applies speech recognition technology to intelligent mobile navigation system to process speech commands and does some deep research on the integration of speech recognition technology with mobile navigation system.The navigation operation can be performed by speech commands,which makes humancomputer interaction easy during navigation.Speech command interface of navigation system is implemented by Dutty Software,which is based on speech recognition system-Via Voice of IBM.Through navigation experiments,navigation can be done almost without keyboard,which proved that human-computer interaction is very convenient by speech commands and the reliability is also higher. 相似文献
5.
Data Fusion in Distributed Multi-sensor System 总被引：5，自引：0，他引：5
GUOHang YUMin 《地球空间信息科学学报》2004,7(3):214-217
This paper presents a data fusion method in distributed multi-sensor system including GPS and INS sensors“ data processing. First, a residual X^2-test strategy with the corresponding algorithm is designed.Then a coefficient matrices calculation method of the information sharing principle is derived. Finally, the federated Kalman filter is used to combine these independent, parallel, real-time data. A pseudolite (PL) simulation example is given. 相似文献
6.
ZHUQing TIANYixiang 《地球空间信息科学学报》2005,8(2):85-89
The methodology of catchment extraction especially from regular grid digital elevation models (DEMs) is briefly reviewed. Then an efficient algorithm, which combines vector process and traditional neighbourhood raster process, is designed for extracting the catchments and subcatchments from depressionless DEMs. The catchment area of each river in the grid DEM data is identified and delineated, then is divided into subcatchments as required. Compared to traditional processes, this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena. Last, the algorithm is tested with a set of DEMs of different sizes, and the result proves that the computation efficiency and accuracy are better than existent methods. 相似文献
7.
Classification is always the key point in the field of remote sensing. Fuzzy c-Means is a traditional clustering algorithm that has been widely used in fuzzy clustering. However, this algorithm usually has some weaknesses, such as the problems of falling into a local minimum, and it needs much time to accomplish the classification for a large number of data. In order to overcome these shortcomings and increase the classification accuracy, Gustafson-Kessel （GK） and Gath-Geva （GG） algorithms are proposed to improve the traditional FCM algorithm which adopts Euclidean distance norm in this paper. The experimental result shows that these two methods are able to detect clusters of varying shapes, sizes and densities which FCM cannot do. Moreover, they can improve the classification accuracy of remote sensing images. 相似文献
8.
WANG Yanbing WU Lixin SHI Wenzhong 《地球空间信息科学学报》2007,10(3):208-212
Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point (IDRVP), to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases. 相似文献
9.
WU HuayiWANG YandongGONG Jianya WU Huayi Associate Professor National Laooratory for momation tngineering in Surveying Mapping Remote Sensing Luoyu Road 《地球空间信息科学学报》1999,2(1):63-67
Polygonal object is a fundamental type of geometric data in vector GIS. The key step of cleaning topological relationship after data collection of polygonal layer is to build polygonal objects from digital arcs. The raw digital arcs may intersect with each other. The algorithm for building polygonal objects after the raw arcs have been split at all intersections is presented. The build-up of polygonal objects in this paper is designed to be implemented by two steps. The first step is to extract all the polygons needed for build-up of polygonal objects from arcs. The second step is to organize polygonal objects from these polygons. For the first step, a tracing algorithm is proposed. The algorithm merely extracts the polygons needed for the build-up of polygonal objects, which is a subset of all the possible polygons that can be induced from the arcs. For the second step, an algorithm based on a specially designed order of polygons is advanced. All the topological relationships among the polygons are sho 相似文献
10.
An optimum vehicular path algorithm for traffic network based on hierarchical spatial reasoning 总被引：5，自引：0，他引：5
Human beings' intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms.It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic,so as to improve running efficiency and suitability of shortest path algorithm for traffic network.The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path.It is argued that the shortest path,no matter distance shortest or time shortest,is usually not the favorite of drivers in practice.Some factors difficult to expect or quantify influence the drivers' choice greatly.It makes the drivers prefer choosing a less shortest,but more reliable or flexible path to travel on.The presented optimum path algorithm,in addition to the improvement of the running efficiency of shortest path algorithms up to several times,reduces the emergence of those factors,conforms to the intellection characteristic of human beings,and is more easily accepted by drivers.Moreover,it does not require the completeness of networks in the lowest hierarchy and the applicability and fault tolerance of the algorithm have improved.The experiment result shows the advantages of the presented algorithm.The authors argued that the algorithm has great potential application for navigation systems of large-scale traffic networks. 相似文献
11.
嵌入式环境下导航地图数据表示和并行调度显示算法 总被引：5，自引：0，他引：5
构造了满足导航要求的地图数据表示多维要素集NDIS_SET，针对嵌入式环境下计算、存储等资源有限的情况，提出了地图数据并行调度显示算法N_PDIS（navigation data parallel display），该算法根据地图显示操作进行模糊图幅预判，并通过动态图幅调度生成两块住图，实时将其中的一块切换至屏幕，算法通过两个并行线程完成。实验结果表明，N_PDIS在显示速度和平滑性方面有明显的优势。 相似文献
12.
兴趣点,又称POI(points of interest)是网络地图、导航地图中重要的表达要素,包括餐饮、娱乐、金融机构、旅游景点、地标建筑、加油站、停车场等人们日常生活中最为经常使用的信息。其数据的准确性、属性的丰富程度、表达的清晰度及其实时显示效率都将影响地图的服务质量。当前POI表达存在许多问题,特别是在用户搜索特定信息时,由于查询结果数据量较大,造成POI的叠置、压盖等,这一问题严重影响了用户对POI信息的查询与检索。地图综合提供了大量的算子算法以实现点或点群要素的选取,但是它们在综合效率方面亟待提高。面向矢量数据处理的并行计算,其数据划分不仅需要满足负载均衡、划分算法高效等要求,而且对于划分后各部分数据在计算前后拓扑关系的保持也显得尤为重要。兴趣点与路划网络是密切相关的要素,两者之间存在着相互依存的空间关系。本文提出基于路划网眼划分兴趣点的方法,既能保证兴趣点的划分效率,又能保证不同分区内POI选取计算的正确性。选择点选取算法中的"圆"增长算法,采用典型试验区域的路划网眼数据,基于不同节点数划分兴趣点数据,实现兴趣点选取并行计算。试验证明,该方法不仅保证了兴趣点划分的均衡性,而且可以提高兴趣点选取计算效率。通过这一研究,对面向矢量数据的地理信息分析、地图制图综合等复杂算法的并行计算具有重要意义。 相似文献
13.
14.
15.
NMEA0183 协议解析模块是导航系统中至关重要的软件模块,该模块的健壮性和高效性直接关系到整个导航系统的性能。为了能及时并高效解析NMEA数据流,分开处理NMEA数据流解析与数据显示,降低解析模块与显示模块的耦合性,提出一种基于正则表达式和MVC架构的NMEA0183协议解析方法。整个解析模块可分为四个阶段,原始NMEA数据流存储,NMEA数据流高效解析,NMEA数据校验,NMEA数据显示。目前该方法已应用到GPS 导航产品中,实测表明,该解析模块高效可靠,数据流解析显示实时性好。 相似文献
16.
17.
计算交叉点是卫星测高数据处理中的重要基础性工作。扩展了交叉点存在的判断条件,可用于判断任意两条卫星地面轨迹是否有交叉点。提出了一种快速计算交叉点的数值算法--矩形收缩算法。采用一个周期的Topex/Poseidon（T/P）卫星模拟轨道和一条海洋二号（HY-2）卫星实际轨迹设计了两个算例,以验证算法的精度和效率。结果表明矩形收缩法可以快速、高精度地计算出全部交叉点。以Envisat数据为例验证了算法计算近极轨道两极交叉点的适用性。该方法不仅可以计算单一卫星轨迹的交叉点,也可计算两个不同倾角卫星的轨迹交叉点,具有很强的通用性。 相似文献
18.
19.
基于功能的导航数据模型 总被引：2，自引：0，他引：2
为同时实现导航系统核心功能，提出了基于功能的导航数据模型，重点论述了该模型中的导航数据的总体组织原则和导航数据组织模型。试验结果表明，提出的数据模型能方便高效地同时实现导航系统的核心功能，适合于导航系统。 相似文献
20.
流域栅格河网提取是数字地形分析的一个重要应用。为减少数字高程模型(DEM)预处理而产生的伪河道及平行河道,提出基于并行化多流向策略的栅格河网提取算法。通过水流传输矩阵模拟水量的自然流动过程,可直接应用于原始DEM。从河网空间形态和算法运行效率两方面与串行MFD算法、R&N算法及D8算法进行对比,结果表明,多流向策略得到的河网与实际地形形态更加吻合,使用并行策略后,算法的效率比也较其他算法有明显提升。 相似文献