1998 Vol. 23, No. 1
As a good choice of more powerful automatic batymetric survey techniques with high accuracy and full coverage,the multibeam strip sounder equipped for the first middle pelagic survey vessel made in China has been brought out recently.Based on systematic analysis to the error sources and error properties of multibeam soundings,the theory models for error processing will be presented in this paper.Especially based on trend surface analysis,the methods for gross error process and strips mosaic,and heading correction will be stressed.
The specialty of reliability for correlative observables is studied.The residual vector can be expressed as a linearization equation of observable's errors and column components of the reliablity matrix (the influence vectors).The correspondence coefficient of the influence vector and the residual vector is used to study on the condition that the observable's error is outlier.In this paper,the theory of correspondence analysis is proposed and discussed.This theory is used to solve the problem of mult outlier analysis in correlative observables.
The difference of solutions are influenced by both observation space and design space.This paper,based on the relationship between the difference of solutions and the estimator of outliers,derives the influence function of LS estimation which is expressed by the estimator of blunders;according to the principle of equivalent weight,realizes robustifying LS estimation to observation space and design space with the method to limit the estimator of gross errors.Examples show that robust estimation with the estimator of outliers has sound robustinity to both observation space and design space.
This paper extends the variance estimation results of equal accuracy corresponding points to unequal accuracy, derives a general formula to estimate the variance of corresponding lines on any point and any directiom, gives the variance estimation formula of the line's length.
This paper presents the error models developed for handling geometric features in three-dimensional Geographical Information Systems.These features include points,line segments and linear features.The developed approach provides a confidence volume model for each feature type.
Space geodesy provides an efficient technique to determine contemporary crustal deformations.At present,GPS is one of the best methods to study the crustal movements in the Qinghai Tibet plateau.Two GPS campaigns were carried out in this area in 1993 and 1995 by Wuhan Technical University of Surveying and Mapping.The GPS measurements show that the Qinghai Tibet plateau moves at about 33.4mm/a to Siberia northeastward at present,which is in agreement with the kinematic model derived from geological evidence.It can also be deduced that the motion rate and azimuth of Bayan Har terrane,Qiangtang block,Lhasa Gangdise block and Himalayan block are about 17.3mm/a,N35°E;25.7mm/a,N33°E;38.9mm/a,N29°E;46.0mm/,N27°E relative to Siberian block(Siberia) respectively.
The deformation of a side slope depends on several factors,such as geological condition,rainfall and underground water.However,the relationships between these factors and deformation can not be surely regarded as determinate and quantitative.In this paper the fuzzy relationships between different factors and displacement as well as the fuzzy approximate inference of displacement are analyzed,then based on this the application of fuzzy artifical neural network to deformation predication is introduced and demonstrated by a practical example of a side slope deformation monitoring.
This paper presents a method of adding annotation to the map especially for the point feature.This method overcomes the shortcoming of traditional methods e.g.Conflict Tracebacking method.It's kernel algorithm that use the Hopfileld neural network to find the best position of feature annotation.The experimental results of running in HP workstation prove that this algorithm has a fairy permanence and high speed.
In this paper,the problem of contour smooth recognition is discussed.The method regarding the trace of intensive contour map based on restraint of smooth is introduced.The effectiveness of the new method is illustrated by experiments.
Based on the analyses of the character of fractal dimension method and Markov random field (MRF),an image texture classification method is presented.Firstly the MRF method is used,then the fractal dimension method.By this way,we not only can supply the information about texture unit,roughness and self similarity of image texture,but also can reduce the error of recepting false and increase the accuracy of image texture classification.
The automatic recognition of human being's hand wrists is the key to the automation of bone age evaluating.Based on acquiring data with digitizing instrument,the theory and method of pattern recognition technique and fuzzy mathematics are studied,which are applied in the automatic recognition of hand wrists.Experiments show that the application of pattern recognition technique is successful.
Geographic information visualization provides powerful tools to represent visually the dynamic feature. In order to meet the needs of map symbol design based on modern technology, this paper extends Bertin's visual symbol system to time area. Four dynamic visual variables which are duration, change rate, change order and rhythm have been added to Bertin symbol system. Some of application of variables is discussed, including enhancing spatial location, describing static attribute and describing dynamic process. After assessing the geographic information characteristics in spatial-temporal change, the paper presents the concept of dynamic map. The definition and generalization of dynamic map are illustrated. As to the function of dynamic map, the paper puts forward three implementation areas: post-processing, real-time tracking and movement simulation.
The progressive graphic generalization approach of linear feature is given in this paper, which comprises the progressive geometric approach based on triangle, and the another one based on graphic basic unit "meander". This approach is better than Douglas generalization method. It can control the self intersection of line, makes map scale become continuous, not be dispersed, can be used in geographic information system. The effect is better in the case of application of characteristic points of a line.
This paper deals with the location processing theory and method of NOAA AVHRR 1A.5 data and presents a non-navigation location processing method. It is unsuitable to directly adopt indirect polynomial correction method in the process from raw data to longitude-latitude projection image.
The principle of depth survey system by photoelectric encoder for oil-well logging, the systems composition and its specific hardware circuit are introduced. Also based on the system error analyzing error correcting methods are given.
An interferometric method is designed for testing the highly precise regular cube, from which a corner prism reflector is cut. The testing scheme and principle are introduced and some related issues such as parameters' selection and attainable accuracies are investigated.
The paper reports on the technical problems of the detailed control planning of the central zone of Hengshui city with the help of comprehensive techniques such as computer scaning techniques、GIS、CAD and the original planning methods. In this paper, the authors put forward the planning characteristics to some medium and small cities, offer solutions to some general problems. Meanwhile, according to the characteristic of spatial information which is necessary for urban planning, the authors advance the new concept of "cooperate spatial unit", which will be helpful to operate the UPMS (urban planning & management system) and enrich the theory of GIS.
Based on having analyzed the working principle and the control interface circuits of the laser-typersetter, this paper described methods for the graphical data storage and the representation, and methods for a bitmap segmenting and output. By using these methods, problems such as speed dismatch between a computer and a laser-typersetter, contrariness between small memory and large amount of graphical dada were solved. Therefore, we can read data from files continuously and deliver data by segmenting. As a result, images can be printed in the laser-typersetter without lossing fidelity.
By using the A/D transformer with middle-low speed two methods of the magnitude sampling are proposed for two types of square wave signals with the middle-high frequency in this paper. It has been proved that those two methods can not only reduce the instrument cost but also avoid effecliely sampling and code lossing.
Atmospheric refraction was discussed by some famous scientists, I. Newton, J. Bradley, P. S. Laplace, F. W. Bessel, etc. The problem of calculating atmospheric refraction, however, has not been resolved as yet. Based on a new variable assumed, a formula was put forward to calculate atmospheric refraction precisely.