1999 Vol. 24, No. 1
The primary combination of remote sensing (RS) with geographic information system (GlS) is mainly realized by the transforms of data structure. Because of its own limitations, it is in urgent need to investigate the integration of RS with GIS in higher levels. In this paper, the different types of combinations between RS and GIS are discussed, and that GIS data should be directly brought into image processing from the first is proposed. A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described. The example for the determination of granularity of spatial data processing relating to run-length-code line is also given.
Rough set theory is introduced and applied in GIS. The methods of rough set theory that are suitable for the problems of attribute analysis and knowledge discovery in GIS are summarized and proposed. including consistency of attribute table, attribute significance, attribute dependence, reduction of attribute table, minimum decision algorithm generation, etc. These methods are valuable in theory and practice and would provide new solutions for GIS attribute analysis and knowledge discovery.
Most of recent researchers believe that a lack of awareness, and problems of accessibility of spatial data are significant bottlenecks to increasing numbers of users and applications. It is not easy for users to get spatial attribute from image of WWW geographic information system (WWW GIS). In order to solve these problems, the vector graphic seamless link with main database model and new WWW GIS system have been developed with Java and JDBC. This paper introduces Internet GIS approach to mutlisource data and geoprocessing, and the principle and functions of Internet GIS.
In this paper, some primary problems and key techniques are analyzed and discussed on distributed processes of remote sensing imagery, including the distributed processing model, supplying environment, data storage management, data sub-block dividing, function decomposition, load equalization and progress assignment of parallel processes, etc.
This paper discusses the basic principles,operations and features of genetic algorithms,and takes the method of maximum classes square error as an example to describe the method and procedure about applying genetic algorithms in optimizing the selection of image threshold. The result of experiments has demonstrated effectiveness of the method.
This paper describes the principles and characteristics of the Wallis filter, and its implementation on point-feature extraction and image matching. Wallis filter is used to enhance the image contrast and reduce the noise, and especially it can be used to enhance/create the textures in the images which are very weak in the original image. So it can improve the number and accuracy of the point-feature extracted and improve the stability, reliability and accuracy of the image matching. In this paper, some results which show the functions of the Wallis filter are also provided.
The traditional two dimension plans and elevations of ancient structure have limited the applications of maintenance and reconstruction and can not satisfyd the current requirements. Based on the architectural survey project of the "Chi Lin Nunnery Redevelopment" in Hong Kong, which has been carried out during 1996~1998, this paper attempts to investigate the methods and techniques of computer-based 3D simulation and database building of the whole engineering for large-scale timber structure, which enables the quality control. There were several key issues including primary data acquisition, 3D modeling and display, assembling the total structure before reconstruction and the quality examination, etc. In this paper, some useful experiments such as the new applications of CCD digital cameras, image and graph processing software (CAD,Photoshop, Photomodeler) to the architectures were also presented. The methods introduced in this paper are suitable for image and graph integrated database building of complicated architectures, it is also useful for the convenient maintaining and reconstructing.
A new algorithm for the real-time GPS orbit determination is established in this paper. In this algorithm, satellite orbit parameters are updated using normal equation addition method. Then, the predicted orbit is calculated according to the numerically differential relationship between the satellite orbit and the orbit parameters. The real-time orbit predicted by this algorithm using the observations of the chinese regional GPS tracking network are analyzed in detail.
The computations of singular integrals are an important chain for practical applications of physical geodesy. It is our purpose in this paper to investigate the problem of computing singular integrals by means of wavelet theory. The fast operation and high precision have been illustrated by a practical example for one-dimension case. As a comparison with Fourier transform, kinds of advantages of wavelet theory have been shown up. Definetly to say, wavelet theory is a great important tool for practical applications to study local gravity field.
Using the five parameters of the gravity field, the metric and connection of the gravity field, the characteristics of force line, equipotential surface, longituade curve, latitude curve, meridian, parallel are studied, and then expressed in the form of five theorems.Five parameters characterize the nature of local gravity field and can be directly measured.Therefore, the local nature of gravity field can be revealed by local measurements.
The so-called Poisson gravimetry boundary value problems, i. e. Stokes problem and Neumann problem for Poisson equation with respect to the disturbing potential, are formaulated in this paper. For solving these two kinds of problems, firstly, Dirichlet problem for Poisson equation is investigated and its integral solution is written out with respect to second Green identity; secondly, by introducing two auxilary functions. respectively. Stokes and Neumann problems for Poisson equation are deduced to Dirichlet problem of sorts, so that their integral solutions are shown in an easy way. The final solutions become a anaddition of two parts. where one is responsive to boundary data, and another to topographies.The present procedure given in this paper opens a new way to study of fining the geoid by using topographies.
In this paper the author has proved that map image system belongs to Boolean algebraic one by using Boolean algebraic difinitions and necessary and sufficient conditions.Thus it gives the theoretical basis and mathematical modes for the automatic map compilation.
In essence, the purpose of sustainable development (SD) is to coordinate the different sub-systems spatinlly and dynamically. First, the systematic and synergetic viewpoints of sustainable development are introduced. Second, the main features of land use system and planning are explained. Then, the paper argues the possibility of application of synergetics to sustainable land use planning,and presents an applicable framework in support for sustainable land use planning/decision making. And then a feasible method integrating GIS and system analysis techniques in the process of sustainable planning is analyzed in detail.The possible research directions are suggested as well.
The paper studies the case-based reasoning technology and case-based design method. Subject to the architecture and structure engineering design cases, the three concepts, case characteristics, case properties and case similarity, are defined. The two methods of case searching. which are subjected to knowledge direction and level weighted, are given. The CtRBD system developed by the authors is introduced.
In geodesy many models are nonlinear ones. The classical methods dealing with these nonlinear models are either linear approximations using the approximation value of parameters or iterations. Some nonlinear models can not be linearized. Linearizing these nonlinear models will reduce the precision of estimators. If using iteration there is different convergence for differents methods or for different nonlinear modes. And it is very difficult to evaluate precision of estimators or functions of estimators. To solve the problems,a direct solution method has been presented in this paper. The influence of quadric term and cubic term has been taken into consideration. The method is an effective and rigorous one. The precision of estimators can be evaluated by classical method in the method. And estimators obtained by the method have fine statistic characters.
In the least squases adjustment, in order to get the solutions satisfying " V T PV =min". It must first construct and solve the normal equation system no matter what adjustment method is used.and then calculate the vectors V , x , V = L + V and X = X O+ x , using the direct algorithm proposed in this paper. we can find the same adjusted results L and X ,in which it does not need to construct and solve the normal equation system.
Based on the theory for M-estimation of the location parameters. the influence functions of the Lp estimation (one dimension and multi-dimension) have been derived and the robustness of Lp estimation has been analyzed while the observational errors obey the contaminated distribution which the data include the outliers disturbed. and the asymptotic variance and efficiency of Lp estimation have been determined too. The properties of Lp estimation have been discussed in the both robustness and efficiency. The observations with outliers disturbed can be processed using Lp estimation which the parameter p should be between 1.2 and 1.5.
This paper builds robust estimation model for correlated observations structured by standardized residuals from the relationship between the observation errors and the function of difference solutions. By calculating and analyzing GPS network with simulative gross error. this model not only has good robustinity to both observation space and design space.but also can eliminate the infulence that the unsuitable prior standard error of unit weight takes on the robust estimation effect.
Terrestrial control surveying. setting out surveying and large scale mapping are called terrestrial surveying engineering. This paper briefly introduces the characteristics and function of a connected sequence and automatic system in terrestrial surveying engineering.It presents the concept and classification of total station surveying system. and points out that the developing direction of terrestrial surveying engineering is connected sequence and automation.
An image measurement system of lens focal length, based on magnification method, with CCD camera is introduced. in which the photosensitive area of the CCD is used as a ruler with high accuracy instead of reading microscope. The system makes it possible the photoelectronic automatical measurement of the focal length. The measued results of two lens is given.
By analyzing sampling method of transformer errors, a newly developed intelligent transformer calibrator is presented. An orthogonal decomposation circuit based on 90° Phase-shift with phase-locked loop is realized. The calibrator can measure the ratio error f and phase displacement δ of both current and voltage transformer automatically.