1993 Vol. 18, No. 2
The Wavelet theory which concentrates on the multiresolution signal processing is nowdays considered to be such a greaty potential theory. Image Processing with the pyramid structure、image understanding and a modern GIS which should have the multiscale function need this theory to support. This paper proposes a new kind of image representation——Wavelet Representation by using Wavelet Transform,improves Wavelet Transform with an arbitary direction,and employs it to extract the building/shadow edges from the aerial im-ages. This wavelet representation in computer vision and image analysis typically helps in two ways:1)allowing ths most economical resolution to be used for each of several image features or objects to be treated; 2) making certain hierarchical structure in an image more explicit and easier to use. The experimental results illustrate this approach is feasible.
In the construction of huge engineering projects,like Superconducting Super Collid-er (SSC),several problems of precise engineering surveys need special attention. Selection of projection techniques and rigorous reduction of geodetic observations are one of the important issues. This paper focuses on the SSC project. In the project the stereographic double conformal projection method is employed. The rigorous procedures for the reduction of GPS observa-tions, gyroazimuths, horizontal angles, and EDM distances from the ellipsoid to the selected mapping plane are discussed.
Presented in this paper is a method for automaticly generalizing urban settlements on a topographic map,an experiment result is also given. With this method,on urban setlle-ment is represented with a network structure, and the generalization is decomposed into two main components, i. e, handling of streets or blocks, and handling of other features within blocks. The experiment result shows some promise of practicability of the method.
On the basis of DDKIN software for processing kinematic observations on carrier phases and results for a vehicle-borne DGPS this paper discusses the following performances for GPS kinematic positoning:——to select a suitable positioning constellation to consider the User Range Accuracies (URA) provided by the navigation message of GPS satellites:——to make choise of a suitable antenna and its setting-up site based on features of the motional carrier:——to process finely 4000SST data at the update rate of one second to adopt Trimvec Plus and DDKIN software written by these authors.
From the view point of the parameter estimation, the model of the least squares matchgin (LSM) can be taken as an adjustment model with additional parameters. Thus the problems which exist in the LSM could be analyzed and solved by the theory of additional pa-rameter adjustment. Based on the theoritical researchs and experimental analysis, the additional parameter is one of the most important factors to influence the qualities of LSM. In this pa-per, a new algorithm called PDFM is proposed,which the parameters(P) dynamic (D) filtering (F) technique is incorporated in the LSM. The obtained experiment results shows, that the PDFM algorithm improves the qualities of LSM at accuracy,speed,iteration times and pull-in range.
With the help of CCD images,realization of high precision positioning and mea-surement has become the basic standard for machine vision and real time photogrammetry system. But deformation and other degradation occurring during transmission are major lim-iting factors of the precision attainable with most current CCD cameras and framegrabbers. So precise radiometric and geometric transmission of images from CCD sensor to memory is a fundamental aspect of CCD camera calibration. The geommetric calibration system of the CCD camera based on the analytical plotter which SOKKIA researched and developed is dis-cussed. And some image processing algorithms are used in the system. The reliability and va-lidity are also discussed. The experimental results of the calibration of the CCD array will be taken as an important quality index for CCD evaluation.
The paper based on general model, costructed density function of free term f (Maximum Likelihood Estimate) and function of residual vector V (Marginal Maximum Likelihood Estimate),the estimate formulae of unit weighted variance are derived in detail, their statistcs properties are discussed,the key factors of unequal between two estimates are analysed,pointed out the basic principle of the MML estimate which can improve the statis-tics property of estimation, the MML estimate of variance is unbiased,efficiency to arbitrary adjustment model.
In this paper,the displacement field due to multi-fault rupture is modelled by fi-nite element method,and characteristics of the stress,strain and displacement changes in a region with a high intensity barrier body are analyzed. The results show that,the drastic changes of the stress,strain and displacement fields occur at the intersection zone of the fault and barrier body.
Geoid undulation can be computed from gravity anomalies using Stokes tech-nique. In addition, we can also compute the geoid undulation from gravity disturbances using Hotine's technique. However,even only the gravity anomalies are avalaible we can compute the geoid undulation using modified Hotine's approaches. In this paper, the ellipsoidal solu-tions of the three kinds of Hotine's approaches are presented, Meanwhile, the author also gives a numerical example to illustrate the amplitude of the ellipsoidal corrections of Hotine's formula.
According to the requirement of seneitivity a method of constructing the criterion matrix for the deformation parameters is proposed in this paper. Baxed on the criterion ma-trix, and taking into account the requirements of reliability, precision and cost, the optimal weights of deformation monitoring network is determined by using quadratic programming.The method of 2nd-order optimal design of deformation monitoring network is illustrated by a numerical example.
In this paper, the necessity and realization of sparsematrix-techniques in adjust-ments of horizontal networks are discussed. Some numerical tests indicate that in many cases Banker algorithm can produce lower profiles than RCM algorithm. With sparse-matrixtech-niques, adjustment programs can not only calculate larger networkes on micro-computers but also speed up calculating and reduce the round-off errors in adjustment results.
SMIS is a Management Information System which processes data,texts and graphs simultaneously. This paper aims to describe the designing idea and techniques of the grapjhic software of SMIS. This graphic software can not only output the information of data, archives and results of surveying and mapping in graph,but also supply good graphic inter-face with which a user can retrieve and manager information conveniently; Besides, the graphic software can provide some statistic graphs which can serve as decisive bases of lead-ing department.
From the propagation-mode field distribution in multimode fibers, a calculation method for Fraunhoffer-diffraction distribution from step-index and α-pewer index fibers is proposed in this paper. Two calculation examples for thses two kinds of fibers are given too.