2008 Vol. 33, No. 9
A new generation framework of spatial information sharing for digital city is proposed,and its technical characteristics is analyzed.According to the service-oriented architecture(SOA) framework,a geospatial information sharing platform is put forward.The spatial data sharing model based on SOA is designed.A prototype platform for realizing multiple-source spatial information sharing based on ArcGIS Server is developed.
The progress in geographic information standardization at home and abroad is reviewed.The result shows that both international and national standardization organizations are all focusing more and more on standardization of geographic information services,instead of geographic data.Based on the comparison analysis,the countermeasures on working mechanism and theoretical content deployment of national geographic information standardization are suggested.
A method for analyzing a planned route considering the effect of changing water level is proposed.The method traces safety contour,and computes dynamically obstacle areas with instantaneous water level.The feasibility is tested by the intersection of the subsection in a route and time-varying obstacle areas,and navigable time window is computed.Experimental results demonstrate that the proposed method can conclude effectively feasibility of the route considering instantaneous water level，moreover it can lead to greater available depths in a route and a shorter distance for safe navigation.
On the basis of the existing methods of point object generalization,and in view of the inadequacy of existing methods,a rough set idea to resolve the problem of point object generalization is put forward.After analyzing the relationship between the classification thinking of rough set and GIS generalization,the feasibility of using rough set method to generalize point object in GIS is explained.The methods and steps of generalizing point object with rough set method are introduced，and the experiment is analyzed.
The model and algorithm of data stream transmission control in the vehicle terminal are put forward.The changing quantity of speed and the changing quantity of direction act as condition of judgment in the algorithm.The judgment criterion is discussed and the equation of data recovery in the monitoring center is proposed.The experimental result shows that the algorithm has an excellent effect on data transmission rate,and the data stream transmission control in vehicle terminal reduces the data transmission rate to only 3.6%.In addition,the recovered data can approach the original GPS trajectories in the monitoring center.
The grid model is common in the reconstruction of the three-dimension terrain.This method has some advantages,but there are some problems needed to be studied,such as how to insure the right elevation of the grid point,how to deal with the abnormal data,how to get the better effect and so on.These problems are analyzed,some methods are presented to solve them and an example is shown for validation.
The inequality constrained least-squares estimation in adjustment model is studied from an entirely novel angle.Inequality constrained least-square problems are first changed to convex quadratic programming problems and then solved for the optimal solutions.The necessary and sufficient conditions on the solvability for optimization solution are given,which consequently gives the general form of least-squares estimation in adjustment model,as well as algorithm that are simple and easy to understand.A comparative calculation of a simulation example indicates that this algorithm can be applied to adjustment computation in the practical measurement.
In conventional GPS RTK tidal level measurement,limited by radio transmitting distance,GPS RTK tidal level measurement can not be used for long-distance and on-the-fly tidal level determination.In order to overcome above-mentioned shortcoming,a new method,which is GPS PPP(precise point positioning) or PPK(post processing kinematic) tidal level measurement,is introduced.Data processing in this method includes attitude correction and transformation of vertical datum.Experimental results show that the method is credible and efficient.
Based on the analysis of the influencing factors and the statistic model of stress-strain,the multiple factors time-varying monitoring model for dam concrete stress-strain is established,in which the multilayer hierarchical and regression analysis methods are combined.Time-varying parameters are calculated based on the new factors which are obtained from the product of the regression coefficients and old factors.In the model,the function of the higher stability correlation factors are strengthened,so as to improve prediction precision of the model.
A new pattern for passive location which based on local gravity field model is presented.A fast Fourier series based local gravity field model is firstly introduced，then by which the measured gravity is expressed as continual analytical equation.Finally the classical extended Kalman filter is introduced to estimate the target position with measured gravity as measurement containing the information of target positon.Simulation is done on 0.2′×0.2′ gravity anomaly database，the result shows that the mean error of analytic equation of local gravity anomalies is less than 0.133 1 mGal，and the mean location errors in longitude and latitude are less than 0.777 0 nmile and 1.244 4 nmile respectively.
A mathematical model of tide zoning correction is proposed.Based on the computational model,a new tidal correction mode using single suppositive grid tide station is designed.The numerical test results show that the new method can reveal the time-space variation of water level,and the seamless joining of regional instantaneous sea level can be realized.
The influence of the undulation of the sensor is analyzed.A new concept of spatial correction of the sensor is brought out.The conclusion shows that within the range of about 10 m of the undulation,the maximum influence value can be about 10 nT.So the spatial correction must be introduced to diminish the influence of the undulation of the sensor.The correction method is studied，and the correction steps are given.
Two new methods for homotopy nonlinear robust estimation method and homotopy restricted-nonlinear method are proposed.Moreover,the corresponding nonlinear functional models for the two methods have also been deduced accurately.Numerical experiment results show that the methods developed have low requirement for the initial value,with fast convergence speed and better precision,which is an effective method in the nonlinear surveying model parameter estimation.
A method and a system for stereo positioning and tracking human's teeth are introduced.The method of computer vision is applied to this system to resolve the parameters of movement of teeth,which are provided for the next step research.The result indicates that the proposed method is intuitionistic,simple,fast and has a high precision，and it can be applied to other domains.
Cloud model,an information transition model between qualitative and quantitative,is beneficial to the processing of uncertainty in remote sensing image.Aiming to deal with uncertainty better,a new approach for image segmentation which integrates cloud model and fuzzy theory is proposed.This approach adopts watershed algorithm to produce clumps from original image.These original clumps are abstracted to cloud models and described with cloud models parameters.The cloud integration algorithm is constructed via the differential measurement rule which is defined by the cloud notion.And cloud models,similar in color,shape and topology,are merged together by integration of cloud notion.Thus,the clumps are combined in different granularity spaces and the multi-scale remote sensing image segmentation is realized.
An advanced matching approach for automatic digital elevation model(DEM) generation from high-resolution satellite images is presented.The DEMs are generated by combination of matching results of feature points,grid points and edges.The new method is applied to SPOT-5 HRS/HRG images over a testfield in Zone of Headstream of Three Rivers,Tibet Plateau,China with variable terrain geomorphologic type.The RMS errors for the whole area are 2-6 m,while for flat/hilly areas the accuracy is about 2-3 m or even better.It is shown that with the proposed automatic DEM generation approach,by using SPOT-5 HRS/HRG imagery,1∶50 000 DEMs can be completed with better accuracy.
A new shadow extraction method for IKONOS in urban region is presented based on the principal component(PC) fusion information distortion.The results show that this shadow extraction method is simple and accurate，not only the shadow of high building but also the little shadow of small tree are all detected.
Character segmentation and recognition of nighttime blurred license plate is a difficult problem for vehicle recognition.An image enhancement method based on Butterworth high pass filter(BHPF) which can select stop-frequency adaptively depending on energy is presented to solve the problem.The license plate can be got after the object location.Because of the influence of vehicle lamp and lower visibility,the object is usually blurred.The vehicle license sharp part with characters is extracted by BHPF depending on images frequency feature.Then the stop-frequency selection is selected adaptively by energy collected in low frequency part.The enhancing high pass filter is designed to enhance images and the object binary image is fit for character segmentation.Seriously degraded nighttime blurred license plate images taken from real world are used in the experiments to evaluate the robustness,flexibility and effectiveness of the approach.The character segmentation and binary result keep useful information more accurately to be used as character recognition.
A new initial match algorithm using six-point groups and area ratio is proposed.Its main idea is to constitute triangulated irregular network(TIN) and six-point groups by point sets,search the pairs of homonymous six-point groups by area ratio and affine transform relations,and then establish initial transform equations between two characteristic point sets by polynomial.According to the counterpart points,the sub-image can be corrected using small panel correction.Experimental results show that it can match two images automatically without manpower intervention and other auxiliary information.
Generalized Gaussian mixture model(GGMM) is used to classify remote sensing images.The experimental results show that the method can obtain higher accuracy than maximum likelihood classification,and obtain more structure details than eCognition on some scales.
A new method based on multiresolution Markov random field(MRMRF) in wavelet domain for multispectral textured image segmentation is presented,in which a variable weighting parameter is employed to combine the character random field and the label random field.And a segmentation result on a coarser resolution is employed as the initial segmentation of the nearest finer resolution by directly projecting the segmentation at the finest resolution.Experimental results have shown the quality of the proposed method to reduce the segmentation error rate.
Based on an investigation with 67 samplings from Taihu Lake in the autumn of 2004,the bio-optical properties including absorption coefficient,backscattering coefficient and irradiance reflectance just beneath the water surface,and the concentrations of the optically active substances are measured and calculated.Semi-analytical retrieval models of three optically active substances(tripton,phytoplankton pigment and CDOM) are developed using bio-optical model.Significant spatial differences are found for the concentrations of three optically active substances suggesting the spatial heterogeneous in the large shallow lake.The estimation models adequately predict tripton,phytoplankton pigment concentrations,and CDOM absorption in well-mixed and optically complex water in the Taihu Lake.
The accelerating genetic algorithm based fuzzy analytic hierarchy process is used to determine the weights of the influencing factors.The classified subsets of the history samples of regional ecological footprint and its influencing factors are constructed using the frequency analysis method.Set pair analysis method is used to quantitatively compute the distance between the nonce and the classified subsets vectors from the view of identical,discrepant and contrary degree，the weighted average of the center values of the classified subsets can be regarded as the predicted value of the nonce regional ecological footprint，and then a scheme of set pair analysis classified prediction method(SPA-CP) is established.The results show that the physical concept of SPA-CP is clear，its computation method is convenient，and its precision is high.
The spatial characteristics of different types of river networks are analyzed.On the basis of 180° assumption and the acute angle assumption for non-networks rivers,the quantitative decision-making table of automatic determination of flow direction is improved.With the flow directions conflict,the principle of subordination of the minority to the majority is applied.According to the flow directions of channels,accumulated numbers and accumulated lengths of channels on a node,the relations of main streams and branch rivers can be reasoned automatically.On the basis of this analysis,the coding method of tree network rivers are studied.The experimental results show the validation of this algorithm.
By mapping qualitative linguistic words into a fine-changeable cloud drops and translating the uncertain land price factor conditions into quantitative values with the uncertain illation based on cloud model,and integrating multiple linear regression model,setting up a linear model between the land price and its influence factors,a new way of evaluating the parcel price is proposed.The case study shows that the potential of using this model for evaluating the parcel price.
Combining the basic theory of cloud model and the process of ecological impact evaluation for land consolidation,the rule of ecological impact evaluation and the cloud models of the antecedent and the consequent are constructed.By translating the uncertain factor conditions into quantitative values with the uncertain illation based on cloud model,the evaluation factor scores and comprehensive scores of Miaotan land are computed.The results are compared with those of composite index computation method and fuzzy comprehensive assessment.