2012 Vol. 37, No. 5
The geographic national conditions monitoring is an important mission of the spatial information science in the new era.In this paper,the necessity and contents of the geographic national conditions monitoring are discussed.Moreover,the role and difficulties of corresponding key technologies,including multi-platform remote sensing,global satellite navigation and positioning,grid GIS,geographic information network services,multi-dimensional spatio-temporal data mining and cloud computing,are deeply analyzed.Finally,some proposals are given for routine monitoring and emergency monitoring of the geographic national conditions.
According to the nearby enrollment policy,an integer programming model is proposed to minimize the total travel cost.Since the relational graph between schools and residences is a typical bipartite graph,the model can be solved by linear programming relaxation exactly.Furthermore,the model is simplified dramatically by eliminating the unreasonable school-residence links.In ArcGIS 10 Geoprocessing framework,a school allocation tool is designed by integrating ArcGIS network analysis.The experimental result shows that the proposed mathematical model and solution method are efficient,easy-to-use and practical for large-scale optimal school allocation.
Gobal spatial autocorrelation and local spatial association were applied in provincial fertility disparity research during low fertility period in 1990s,to reveal spatial-temporal pattern of fertility distribution.The results indicate that provincial fertility level in China has statistically significant positive spatial autocorrelation with up-rising temporal trend.Meanwhile,Xizang and Guizhou,these two regions of potential extreme high fertility rate have great contribution to the global Moran's I.Moreover,the divide of the east and the west still exists,specifically regions with significant high-high cluster pattern stably shrink to the north-west and the south-west,which shows these regions have little disparity with Sichuan region of low-high spatial outlier pattern;while regions with low-low cluster pattern spread from the north to the central,which suggests that they have much disparity with only Jilin,Beijing-Tianjin and Jiangsu as significant regions.
In order to achieve the semantic of feature from multi-WFS services,we propose a five-tuple feature ontology model.Firstly,the automatic construction methods about feature ontology are employed.Then,the multi-spatial relations are formalized among features.We extend the inference rules with logic and spatial reasoning to implement the reasoning retrieval on features.Finally,based on the ontology model and the combined inference rules,we give the algorithm of feature semantic retrieval.The results show that the method is supered usability.
This paper proposes a catalog service solution for geographical information.It is a solution that effectively integrates crawling and search techniques,dynamic monitoring techniques,and quality of geographical information services theory.A prototype focused on Web map service was established that not only solves the search,monitoring and quality problems successfully,but also satisfies the users' desire to manipulate experience and retrieve results efficiently.
3D models with high quality and realistic texture is a very significant topic in the field of digital museum,heritage conservation,and so on.For the small bronze artifact Shuangniaotaotiewenkushentuogu and other small objects,we propose a new texture reconstruction method of high-automation,high-efficient,and high-quality.Based on the structure light scanning system with common digital camera,our approach mainly resolved the registration for a single high-resolution image,and the seamless texture generation from multi-view images.Massive reconstruction tests proved the feasibility and validity of this method.
We propose a non-linear regression model based on normalized snow index(NDSI).The sample data obtained in Alaska,Siberia and Inner Mongolia were used for regression analysis and model parameters estimation.The accuracy of the non-linear regression model was verified and compared with the linear model using the experimental data extract in the Tianshan mountains and Qilianshan mountains.The results show that the proposed model gives a better fit to the sample datas and the ccuracy of the non-linear regression model is higher than the linear model.
An adaptive template-matching framework integrating the Fourier-Mellin and Affine transformation is proposed for implementing area-based matching toward complicated image motion or geometry distortion.Firstly,IR(interest of region) with remarkable intensity distribution is automatically generated from reference image by dividing image into grids and within each grid,applying the Moravec operator to extract the most distinct point as the center of IR.Secondly,based on Fourier-Mellin transformation,global image motion is coarsely estimated and with estimated motion parameters,obvious geometry distortion is removed from each IR to obtain its "coarse" template as well as prediction of IR in other image is obtained.Thirdly,with IR "coarse" template and its prediction in other image,rigid affine transformation model is sought though iterative hypothesis-validation procedure and based on the model,"fine" template ensuring a locally maximum NCC computation is generated for each IR as well as its conjunctive is determined.Finally,the experimental results over different view/source of stereo image show that the proposed approach is robust to complicated image motion or geometry distortion.
We give a proposal to obtain the new class property of each changed image segment using MRF graph model.The new class property of each changed image segment can be gotten by calculating maximum posterior probability through MRF graph model descripted by Gibbs distribution.The result could be regarded as the initial result and then be further analyzed using class spatial-relationship probability matrix.The experimental result shows the feasibility of this method.
We present a multi-pose face recognition method based on two-factor analysis model.The method refines the traditional two-factor analysis model,and partly solves the problem that facial feature is sensitive to the pose variation.Large number of 3D face data is trained in the two-factor analysis model to get robust and differential pose factors.In the experiment of FERET facial database,the best recognition accuracy is 92.5%.The results show that both the global and local facial features maintain a good pose variation robustness and high significance of feature descriptor after the pose factor separation.
As a manifold learning method,Isomap has been widely used for making nonlinearly reduction for hyperspectral image.However,during the construction process of the shortest path graph,the boundary points,which are not noise points,have always been omitted for the consideration of the stability of the graph.Therefore,the PLS method is introduced to repair and simulate the manifold coordinates of the lost points in the shortest path graph.And the simulated manifold coordinates have been evaluated from two different aspects to verify our method.The results show that the simulated manifold coordinates agree well with the real one.It will be quite useful for further classification or visualization with low dimensional manifold image.
Considering topographic features and view-dependent characteristic,a simple evaluation function for quad-tree subdivision was used to generate dynamic multi-resolution terrain model in real time.While 3D scene roaming,a mechanism of multi-level buffering was used for data scheduling and rendering under the condition of quickly viewpoint transformation.At the same time,an adaptive LOD scheduling which comprehensive consideration of frame rate and subdivision evaluation function was proposed.A multi-level texture mapping method consistent with the terrain scheduling was used to render the image texture.At last,the algorithms were achieved by programming,and the large-scale 3D terrain visualization was realized based on the simplify methods.
Considering the micro-state of rural residential land,the appraisal index system of the rural residential land comprehensive influence is constructed to identify central village,maintaining village and minor residential area(relocation village).The central village influenced region is delimited according to their comprehensive influence to find out the location of the minor residential area by using weighted-Voronoi diagram,which is the one of spatial segmentation methods of urban geography,to maintain their original social spectrum and daily habits.
We combined physiological theory with classic GIS path planning method,and a model for calculating walking energy expenditure per unit distance was established based on recent physiological studies,and an approach was made to convert road real length on different gradient to corresponding level distance using the model.With this approach,real path lengths were transformed into equal level lengths before being measured.The results show that both gradient and distance are taken into account in this algorithm,and the route provided was more reliable and useful than that by shortest path algorithm for pedestrians.
To improve the common representation method of scree areas by pasting texture in 3D topographic map,we present an automatic modeling method of scree based on fully considering many impact factors such as visual effect of illumination,gravity effect,etc.The method accords with the people's spatial cognition custom.The results show that it could be better to simulate the distributive characteristics and the individual appearance of scree under the different illumination conditions and elevation conditions in scree ares.This study will be helpful to build the modeling of other similar relief symbols automatically.
From the GPS data of crustal movement observation network of China(CMONOC) from 2000 to 2004,the precipitable water vapor time series of all stations are obtained.According to the different climate types,the GPS stations of CMONOC are clarified.During the comparison of precipitable water vapor among different climate types,the values of precipitable water vapor in different regions were arranged from lowest to highest.These regions are of alpine climate,temperate continental climate,temperate monsoon climate,sub-tropical monsoon climate and tropical monsoon climate.The results show that the waveform changes of precipitable water vapor of different climate types are different.
The definition of general reliability of measurement is proposed for the first time.We discussed the extended error theory,and analyzed the systematic effect of stochastic error and the randomization of systematic error.The concept of uncertainty in measurement and the application of general reliability are discussed,it is valuable for surveying scheme design,data adjustment,verification of measuring instrument and the setup and explanation of standard for surveying.
A new method concerning how to eliminate leverage points with outliers from the conditional subset is considered.Firstly,several subsets of observations are selected randomly from all observations in accordance with the percentage of leverage points with outliers in order to obtain one subset containing no leverage points with outliers.Secondly,the conditional subset is selected from the subsets that are selected above according to the sum of squares of the residuals.Lastly,a new algorithm is given by connecting our procedure with the Gibbs sampling.
The batch method and EM algorithm have been used to process the observational data of geostationary communication satellite.Using the inspection methods of skewness and kurtosis to test the normality of residuals processed by batch methos.In this case,the observation datas of Xinnuo statellite containing not only accidental errors,but also systematic errors.Batch method in dealing with systematic errors of observation data,the results are not reliable.Compared with the batch method,using random walk model to describe the system error,EM algorithm based on digital filtering method with systematic errors in the data processing is feasible,reached a certain extent,improved the precision of the data processing.
Based on the research and analysis on the current computational models of sound ray tracing,a set of more precise computational formula are derived.The basic principle of the method is that the average sound speed is calculated using the integral of the sound line arc infinitesimal,then a precise beam footprint position formula is obtained.The theoretical analysis shows that the average speed of the traditional ray tracing technology is the approximate solution of the improved sound ray tracing technology when the circular path of the sound ray is taken as chord of the arc.The experimental result shows that the improved sound ray tracing arithmetic is more precise and practical than the traditional sound ray tracing technology.
According to the characteristics of face rockfill dam surface and the points collected by the surveying robot are much and their height difference is small,to achieve optimal fitting effect compared with real height,a method was proposed for fitting height by radial basis function(RBF) neural network based on multiquadric(MQ) function and optimal smooth factor by means of mathematical statistics and progressive approach method.To verify its feasibility,we carried out the surface height fitting of face rockfill dam with the data from surveying robot.The results show that the method can get better fitting effect and has higher precision than many common fitting methods.So the method maybe more suitable for surface height fitting of face rockfill dam and can provide the reliable data base to monitor the rolled thickness and construction quality for face rockfill dam.
The trait of sphere target is analyzed,the generating process and characteristic of spherical center error are described by laser radar equation.The distribution of spherical center error with laser incident direction is researched and counted,and then determined by polynomial fitting model and simulation of sphere surface.The systematic characteristic of spherical center error is verified by the measured data and a weakening method is proposed.
Using 8 descending track Envisat ASAR images,time series of different interferograms and consequent co-seismic deformation field of the L'Aquila earthquake(Mw 6.3 on 6 April 2009) were obtained by PSInSAR method.Furthermore,deformation processes of rupture zone were numerically analyzed using Delaunay triangulation algorithms based on above results.The results show that:① The rupture center located at a low elliptic depression region.The cracking propagated along southeastward direction with an orientation of 135° and covered about 22×14 km2.② The deformation area was mainly located in the rupture center,which was formed at the epoch of earthquake and thereafter.The displacement of rupture center in radar line of sight was as high as 150 mm.③ The numerical analysis results of the entire deformation process in rupture zone detected by Envisat show that: from Jan.2008 to Feb.2009 before the earthquake,the ground deformation of target zone was not significant;from Feb.to Apr.2009 after the shock,the deformation field of rupture zone changed rapidly with a maximum of subsidence of 130 mm;from Jun.to Jul.2009,the settling velocity of deformation field was slowing-down;while on 30 Aug.2009,the subsidence rate shown from last SAR image turns to accelerate,and total settlement amount in rupture zone reached 150 mm.
A fast algorithm is proposed for the direct discrete summation of Stokes ’ and Hotine ’ s integral,the integral kernels are expressed as the functions of the latitudes of computation point and running point and the longitude-difference between them,the symmetries of the kernels are exploited so that they may only be evaluated once for all the computation points on the same latitude,the computation times of fast algorithm are far less than that of ordinary algorithm.The numerical simulation based on EGM2008 Earth gravitational model shows that the fast algorithm is far more efficient than the oridinary algorithm that the problem of numerical inefficiency can be effectively solved.Besides,the new algorithm retains the attributes of surface integral and can be used to replace 1DFFT for evaluating Stokes ’ or Hotine ’ s integral.
The principle of bathymetry inversion with GGM method was discussed,the detailed calculate process was presented,and the bathymetry in south of Emperor Seamount was calculated.The accuracy of GGM bathymetry is better than ETOPO2 through the comparison with vessel depth data.Compared with classical methods,GGM method does not need to introduce a prior bathymetry model and take into account the isostasy of the seabed.The model is simple and easy to calculate.
The error models of cumulative geoid height influenced by the errors of intersatellite range,range rate of KBR system and the satellite position of GPS receiver are deduced respectively.The combined error model of cumulative geoid height influenced by range rate error and satellite position error is also constructed.The results show that the precision indexes of inter-satellite range,range rate of KBR system are about 0.64×10-6 m,0.8×10-6 m / s,respectively.While the precision indexes of satellite position of GPS receiver is about 2.1cm.The cumulative geoid height error of Earth ’ s gravity field model in 120 degree,which is recovered by the combined error model,is 26cm in the presence of these precision indexes.
The purpose of this investigation is to illustrate the effects of receiver antenna snow accumulation on GPS phase observables.Firstly,the effects of snow cover on carrier phase signal field strength and power are analyzed.Then a simplified model is developed to estimate GPS phase propagation delay due to the complicated mixing ratio of snow and resultant complex refractivity.The theoretical analysis revealed that the magnitude of propagation delay,which can be significant in high-accuracy GPS applications,depends on satellite elevation,the water content of snow and snow depth.At last,the daily coordinates of two stations with ten continuous days of GPS observations are estimated using precise point positioning technology.The results indicate that antenna snow cover have an effect on the antenna phase center,and induce horizontal and vertical errors of several centimeters or even more.
We present a kind of signal performance evaluation method for generic mismatch processing mode.On this basis,four reference modulations for compass B1 band interoperable signal are proposed,and within which,an optimal reference modulation is given based on the comprehensive performance.Compared with existing interoperable signals,the proposal modulation has independent intellectual property right.And it has superiorities in demodulation and tracking,as well as in the flexibility.The experimental results can be regarded as a feasible reference for the design and optimization of the compass signals.
By surveying the classic gamut mapping algorithm,we summarized those relevant factors of influencing image quality when gamut mapping executing,then established an optimization mapping model based on analyzing the weight relationships among those factors,designed and actualized an image-dependent gamut mapping algorithm.The experiment has confirmed that the new algorithm is better than SGCK and HPMINDE recommended by the ICC.It can keep the best visual conversion effects.