2005 Vol. 30, No. 7
Automated generalization in condition of digital mapping is an international problem, conventional model and algorithms can not fulfill its requirement now. On the base of that most problems of cartographic generalization can be treated as optimizing problem, this paper carries genetic algorithm into the study of cartographic generalization in a creative way and builds a model of cartographic generalization based on genetic algorithm. Taking the selection of point as example, this article lucubrates the keys of the model—coding, fitness function, etc. Examples with actual experiment demonstrate that the model of cartographic generalization based on genetic algorithm is a new and feasible method to solve the problem of automated generalization in condition of digital mapping.
In this paper,the issues about digital video encryption algorithms include the essential cryptogrammic knowledge and techniques, the open problems and the most important schemes, research hotspots and their progresses, and prospects are summarized and overviewed. Through the analysis of current encryption schemes for encoded digital video, it is pointed out that an alternative encryption scheme based on characteristics of source data format for compression encoding of digital video is the future trend of video encryption.
According to the orbital dynamical model and the kinematics model of satellite attitude, this paper developes an extrapolative location model. Testing the model on CBERS-2 high resolution satellite imageries of central China, when the depth of extrapolation is 480 km, the planimetric precision is 96.636 m including the measurement errors as well as the modeling error over than the 568 m which is the planimetric precision of systematic rectification. Thus, the validity of extrapolative location model is verified. The results show that the potential of using this model for rectifying other high resolution remote sensing imageries and object location on the condition of being short of ground control points.
A method of floor area ratio extraction is proposed by extraction of construction shadow in high resolution remote sensing images. Image processing is used firstly to extract large range construction shadow in urban building area,then these shadow are vectored and the shadow coordinates are converted to spell image contiguity breadth. Secondly, FAR is calculated based on regress analysis between construction shadow area and construction area by taking into account of construction’s orientation. At last,FAR of Shanghai central city zone is extracted and the results are validated. The result indicates that the method can extract FAR in high resolution satellite image effectively.
This paper studies the filter of image with polarizer salt and pepper noise based on DMN. And it is pointed that there are abilities of fine distinction of pixel in image due to the features of decaying of threshold value, and linking of node of networks. And therefore the approaches are posed for image filtering under the control of DMN. The algorithm only calculates the mean of pixels that are related noise, and place the noise pixel. And what is called sub-mean filter algorithm. It is carried out that noise image is filtered by stubborn self-adapting method. The experimental results show that the method has better behavior of filter.
On the basis of the analysis of characteristics of Fuzzy logic and neural network, the possibility and inevitability of the combination between them are introduced. It gives the FNN-LM algorithm and the method to determine the network parameter. Relative to other models, the superiority of FNN deformation prediction model is showed by the historical displacement prediction models of twelve points of Dongjiang dam for their short training time and high prediction precision.
In this paper, the basic technical needs of the deep space surveying and control network (DSN) are firstly summarized. Then, the techniques, the constituents and the distributing of Chinese satellite surveying and control network and other radio observing establishments are introduced. Lastly, with the primary Chinese satellite surveying and control network and other observing establishments, some projects are analyzed and stated.
In the research of WADGPS receiver, authors built general proposal GPS operational platform using TMS320C32 32-bit DSP chip, constructed double-length floating data type and high precision mathematic functions. Base on these works, the work of algorithm optimized is done. This paper also shows the flow of the DSP firmware and the running results.
The main effect on the GPS signals of ionosphere and ionospheric refractive model are researched in this paper; then the dual-frequency corrected model of ionospheric refractive error is concluded. Aiming at the third frequency added in GPS Modernization, the triple-frequency corrected model of ionospheric refractive error and the ionosphere-free combination model of triple-frequency is deduced. The second-order ionospheric effect can be corrected and the positing accuracy can be increased through these models. At the same time, these models supply the strong support in other GPS techniques such as separating error sources in GPS, cycle slip detection and etc.
This paper derives a plate motion model called GVM1 based on space geodesy techniques by the integrated data of GPS and VLBI. After selecting the proper stations of GPS and VLBI, establishes the plate motion model and unifies the reference frame of GPS and VLBI, resolves the relative Euler vector among plate north American, Eurasian, Pacific, south American and etc. Comparison between GVM1 and the geological plate motion model NUVEL-1A indicates that the plate motions from space geodetic observations are generally consistent with those from geological observations. The EURA-NOAM Euler pole from space geodetic observations is near to that of NUVEL-1A; the Australia plate has been steady in recent years; those stations located in the boundaries and joints could not represent the south American plate motion; the Pacific Euler pole relative to another plate pairs is consistent with the geological model, which indicates that the plate motion Euler vectors are improved greatly by the integrated data of GPS and VLBI.
Focused on the task of carrying out GPS occultation observations with a receiver set on LEO satellite, this paper developes the LEO orbit simulation system based on which the occultation events can be simulated taking into account the geometric relationship of the satellites and the field of view of the receiver antenna. In this paper, the impacts of 4 types of LEO orbit parameters—argument of latitude(AOL), right ascension of ascending node(RAAN), orbit height and inclination—on the distribution and number of occultation events a single LEO satellite observed are discussed through simulation and some conclusions are drawn.
The principle of (least squares spectrum analysis, LSSA) is introduced in this paper based on the least squares parametric adjustment in vector space. A possible strategy is given for the analysis of time series obtained from the Canadian Superconducting Gravimeter Installation (CGSI), which exhibit minor gaps (unequally spaced), offsets, spikes (seismic events) and variable weights due to different noise levels.
A new fast difference iterative solution model is proposed to adjust parameters of surveying and mapping by least-squares method with multi-type, multi-precision, multi-source dynamic and nonlinear data in digitalized construction, which can avoid computing derivative completely and reduce calculation of Jacobi matrix. At the same time, a matrix sequence, which can approximately substitute for second-order partial derivative matrix by recurrence method, is constituted to make the rate of convergence of the algorithm model faster. This creates a new solution to solve the generalized nonlinear least squares adjustment of surveying and mapping by parameters.
On the basis of the judgement matrix of gross errors judgement equation and the function formulation of correlation coefficient between two testing values, this paper proves that both the mathematical models, in fact, are equivalent. The results of a familiar example which gross errors in the observations can not be identified based on judgement matrix are appeared to be exactly the same as that correlation coefficients between their testing values are equal to 1. Furthermore, the gross errors detectability and identifiability of observations analyzed by the judgement matrix would be more convenient and simple than by the method based correlation coefficient.
This paper compares and analyzes the change trend of zenith tropospheric delay (ZTD) and integrated water vapor (IWV) at BJFS, LHAS and WUHN stations in July 2002, and puts forward a new method which can calculate directly IWV using GPS ZTD without other transformations. The IWV calculated by the method is validated with the IWV computed by traditional method. The results show that the method is feasible
According to the Earth synchronous satellite positioning principle, multi-results and non-results are analyzed when the station height is given using DEM. By observation equations, the criterions of judging multi-results and non-results are obtained. Introducing the method of dummy topography projection, the subclass π_2 of positioning results belong to sub-steady convergence is gained.
In this paper, a new correlation processing method-vertical correlation method is presented. A mathematics principle of vertical correlation method is studied and examples of simulation and application are given. The results show that vetical correlation method has strong noise-reduction ablity, eliminates strong-noise’s influences to calibration precision and raises greatly frequency-domain calibration precision for very broadband seismometer.
This paper puts forward a vertex removal simplification algorithm based on visibility preprocessing. To deal with huge amounts of terrain data set,The space index system with high efficiency is created and applied to accelerate the visibility preprocessing including view-frustum culling,back-face culling and hiding-face culling. The model which had been preprocessed is simplified further by the vertex removal algorithm based on curvature. The experiments show that the visibility preprocess can accelerate the rendering to a great extent and the rendering velocity is independent of the model complexity.
This paperpr proposes a method to discover automatically feature change based on topographic map database, field patrol, topographic map surveying by compared the original data from database with the surveying data later. This method is of high efficiency and accuracy, and it is used to discover automatically features change before Beijing topographic map database updating on scale of 1∶500.
In order to solve emitter recognition problems in such practical reconnaissance environment, attribute mathematics is introduced. The basic concepts, the theory of attribute set and attribute measure are described in detail. A new attribute recognition method based on attribute measure is presented in this paper. Examples of recognizing the emitter purpose are selected to demonstrate this new method. Moreover, the algorithm is compared with classical statistical pattern recognition through simulation. Experimental results show that this attribute recognition method is accurate and effective.
The previous researches on spatiotemporal databases were concentrated on data models and languages, they are not the implementation of spatiotemporal database systems. Based on this problem, a method of implementing spatiotemporal database systems using the Informix datablade technology is presented. The detailed fundamental spatiotemporal data model and the procedure of implementing spatiotemporal datablade are discussed, as well as the experimental results.
On the basis of the analysis of the characteristic of mine laneway, a mine laneway is broken up into the laneway body and the laneway node, which are rebuilt into 3D model respectively, and builds the topology among laneways. The results show that the method is feasible and make a good base for the further spatial analysis.
In this paper, the authors aim at the problem that GPS receivers often lose useful signals because of the effect of various interfering signals in the period of receiving signals. As a sequel of it, GPS receiver will be out of work and can not provide users with its excellent support for accurate navigation and positioning. So the authors put forward a method to resolve this problem by adding an adaptive anti-jamming module to the antenna of GPS receiver, and select TMS320C6416 chip to realize this design.