2005 Vol. 30, No. 12
In order to simulate crustal deformation in large scale,a 2D spherical NMM is developed from plane NMM.The new model adopts spherical triangles as mathematical covers.The stiffness matrix,initial stress matrix,point load matrix,body load matrix,inertia force matrix are derived,which lay a foundation for the new model.
This paper analyzes the effect of two kinds of altitudes provided by barometer and digital map on the position precision,and deduces the error expressions.Many simulation results show that in the two cases,the effects of the same altitude errors on the positioning precision is identical,and the rules that the two altitude errors affect positioning precision can be expressed that altitude error has little effect on the east-west position error,but has large effect on the south-north position error,the lower latitude the larger effect,the higher latitude the less effect.
The height changes of tide gauges directly influence ocean level observation.For research on ocean level variation in large region or globe,the land vertical displacement must be considered.In this paper,two sessions of GPS and absolute gravity observations in 2001 and 2003 are used to determine the horizontal and vertical motion of China coast in ITRF2000 and Eurasia frame.The difference between results of continuous observation and periodic observation is discussed.
A new data fusion method is put forward on the basis of analyzing the virtue and shortcoming of the previous data fusion methods of multiple sensors.The final results avoid the affection of the position errors accumulation because only the velocity and acceleration parameters of DR are used when combined with the GPS observations.When the GPS signal is interrupted,the final positions are predicted by using the velocity and acceleration parameters but not estimated directly from the DR system.The feasibility of this method is certified through a simulating example of GPS/DR.
This paper analyses the reason of the formal difference of p-norm distribution density functions,improve 2 problems in the deductions of p-norm formulating,and puts forward the equivalent proof of 2 different forms of p distribution density functions.It is convenient for popularization and application of the p-norm theory in surveying and mapping.
In this paper,a new method for edge detection from complex scenes based on gradient histogram and variance within clusters is proposed(cluster algorithm based on gradient histogram,CAGH).After analysing gradient histogramming by "Non-maximal suppression",edges can be extracted with the gradient threshold based on the variance within clusters.In comparision with other methods for edge detection of vehicle license plates from complex scenes,this method has better adaptability and more efficiency,which generates one pixel width edges with good connectivity and independence,is good to subsequent feature extraction and pattern recognition.
This paper proposes an approach for automatic extracting shadows of building from remote sensing image on the basis of the method that gray statistics is done in one side of the structure lines to detect shadows.The approach,which combines constraints of gray,geometry and context,and others assistant information,realizes the shadow extraction of buildings.Finally the image of IKONOS and aerial photograph are experimented to extract shadows of building.Results of the experiment show that this approach is effective and robust.
Shadow is a general phenomenon which occurs in SAR images,and it has many vital applications in various aspects.A new solution of shadow extraction is presented in this paper.By Sigma filter and optimal threshold segmentation algorithm,Shadow can be extracted from InSAR coherence.Both the theoretical analyses and the experimental results indicate that the proposed method is a highly efficient method of shadow extraction.
The paper proposes a dynamic data updating algorithm for image superresolution.Based on Delaunay triangulation and its local updating property,this algorithm can update the changed region directly under the circumstances that only part of the source images has been changed.For its high efficiency and adaptability,this algorithm can serve as a fast algorithm for image superresolution.
This paper present a small targets detection approach based on independent component analysis in hyperspectral data.Firstly,this algorithm uses fast independent component analysis(FICA) approach to collect the targets information hided in the high-dimensional data and projects them into low-dimensional space.Secondly,selects feature images with kurtosis.At last,extracts small targets with histogram image segmentation method which has been labeled by skewness.
A new method is developed here to model daily evapotranspiration over large areas by combining remote sensing data and ground-based meteorological variables.However,many differences of surface parameters between transpiration and evaporation are more complex because the transpiration from vegetation is affected by the physiological characteristics of the vegetation.Thus,this model describes the parameters separately.The model is validated at large scale with homogeneous surface conditions,good agreement is obtained between model estimates and the measurements at ground stations.
This paper introduces an improved method for extracting image texture characters from the large-scale remote sensing image on the basis of retrieval based on image content,which has over 500 000 pixels.This method divides image into sub-images and extracts their texture characters with the method of co-occurrence matrices firstly,then calculates some statistics of these texture characters using a statistical method like Hu's invariable moment.So we can extract a group of texture characters connected with the texture's position in image.It improves the method of co-occurrence matrices and makes the texture characters contain more information.This method can be used in large-scale remote sensing image retrieval and classification.
Multi-level spatial index techniques are always used in the management of large spatial databases.This paper presents a novel 2-level index structure,which is based on the schemas of spatial grid-file,Hilbert R-tree and common R-tree.This new structure is named H2R-tree,and detailed algorithms are given.Using real data for test,the new method is proved to show superior performances in several aspects.The first,it suits for grid management with no additional demand;the second,H2R-tree shows better query efficiency;the third,it supports local independent update;the forth,it is suitable for distributed data management,and easy for realization;and the last,former bulk-loading methods can be applied in H2R-tree easily.Generally,H2R-tree is specifically suitable for the indexing of highly skewed,distributed,and large spatial database.
In this paper,the theory which characterizes the topographic characterics of large watershed using fractal information dimension(FID) is firstly discussed,and the FID mathematic model for the large region based on GIS software platform is provided and established.Accordingly,the FID calculation method is discussed,and then the software to calculate FID values using avenue language based on Arcview system is programmed.
According to the characteristics of WebGIS and spatial data,a distributed cache system is proposed in this paper.Some key problems needed to be resolved in the implementation of distributed cache system including cache spatial data selecting,distributed cache building,distributed cache management and cache consistency maintaining are discussed.Finally,the performance of this distributed cache system is analyzed with a case study.
Integrating the theory of Distributed Virtual Geographic Environment(DVGE) and HLA,this paper designs the architecture of DVGE based on HLA.The data flow and the object models of the architecture are also discussed.The architecture basically meets the need of DVGE in real-time communication,distribution,collaboration,reusing and inter-operation,expansion,and standard.
This paper presents an approach for extracting complex spatial concepts from unstructured text.By defining several spatial semantic roles based on the characteristics of geo-spatial information in natural language,the authors extract spatial entities,spatial relationships among entities and spatial procedures by means of spatial semantic annotation,semantic phrases recognition and pattern match.It tries to solve the problem of unable to get deep spatial semantics in common IE.The primary experiment shows that it has a good precision and a similar recall comparing to common IE systems.
On the basis of the workflow management system's standard model of WFMC and the workflow object implementary model of OMG,this paper develops the design and implementation of the workflow engine module,the workflow engine database and the workflow engine object based on J2EE.
In the course of collection and edition,the data model,the collecting method and the quantity control means of 3D data are much more complicated compared with 2D data.A compatible 3D data model of cloverleafjunction is very important for collecting data of cloverleafjunction of city.Because of affiliating 3D information,catching between data is no longer a simple complete consistence among coordinates of nodes,but is divided into the 2D catching for plane coordinate(x,y) consistence and the 3D catching for stereoscopic coordinate(x,y,z) complete consistence.For practical application of navigation of vehicle,the given data model of cloverleafjunction in this paper is preferably capable of expression of cloverleafjunction of city.The practice of data production on a large scale indicates that the data model is feasible to collect data of cloverleafjunction.
A new method for automatic extraction of structure lines is developed by the new(idea) includes 3D physical analysis and 2D geometrical analysis.The new idea is based on the fact that the flown line whose start point is a valley point at upriver always flows along the lowest direction,and the flown line is also a valley line.A real contour map was used as testing data.As the result,the valley lines extracted automatically by this method can basically represent the topographic features of the corresponding topographical map.The new method takes advantages of 2D geometrical analysis and 3D terrain analysis and it is effective.
On the basis of analysis of various algorithms,an anti-aliasing algorithm called brush method is presented in this paper,which is suitable to map publishing symbol.After introducing the basic principle and implementation of Brush Method in detail,its effect and efficiency are evaluated through experiment.