2003 Vol. 28, No. S1
To establish the modern geodetic datum of China,the characteristics of modern geodesy and the practice of China should be taken into account simultaneously.So the following four factors should be focused on especially:high accuracy,covering all of the territory including land and ocean,three dimension,and dynamic.Establishing the modern geodetic datum is to supply a reliable and proper basic frame of the geographic space for users anytime and anywhere,and its task should include the establishment of planar datum,height datum and gravity datum.
Firstly the problems and difficulty of current change detection techniques are presented in this paper.Then according to whether registration is done before change detection algorithms,the author classifies change detections into two categories:change detection after image registration and change detection simultaneous with image registration.For the former,four topics are introduced and described.For the latter,three categories are discussed.Last the future prospect for change detection techniques is given.
GRACE's payload comprises eight system:K-band ranging system(KBR),accelerometer(ACC),GPS space receiver(GPS),laser retro-reflector(LRR),star camera assembly(SCA),coarse earth and sun sensor(CES),ultra stable oscillator(USO) and center of mass trim assembly(CMT).For the determination of the earth's gravity field,KBR,ACC and GPS are the key instruments.In this paper,the KBR,ACC and GPS are analyzed in detail,and the others are also introduced briefly.Some conclusions and suggestions are given.
This paper out lines the basic situations,requirements and proposes tasks of the national geodetic infrastructure.It is proposed that the national space-geodetic network consists of continuously operating reference stations,the first,second and third order sub-networks.
This paper reviews the development of CORS(continuous operational reference station) technique of GNSS(global navigation satellite system),describes the developing trend and characteristics of this technique,and points out several problems that currently exists in the development of this technique in China.
Voronoi diagram was widely applied to GIS spatial data modeling and spatial analysis in the past ten years.This paper overviews its applications to spatial interpolation,terrain modeling,facility location analysis,spatial recognition as well as spatial data generalization.Future research directions are also briefly summarized.
This paper discriminates the 2'×2' gravity field,which is derived from altimetry satellite of Seaset,Geosat,ERS-1 and Topex/Poseidon,to elicit gravity anomaly correlated to sea floor.Using the gravity anomaly combined 5'×5' sea floor bathymetry data of ETOP5 to inversion,we can attain 2'×2' sea floor bathymetry result of China sea and its vicinity.
This paper present s using spatial database technique to organize and query the geodesy data,introduces the optimization design of the system,the data model of the system,the application technique on web database and data query system based on WebGIS,then deploys the system based on J2EE.
To calibrate some parameters of the digital camera such as principal point,principal distance and optics distortion ratio for the precision and reliability,a high accurate calibrating field for digital camera is built.Spatial analysis is applies to reduce the ill-conditioned state in the system so as to improve the reliability of the calibrating result of digital camera.
This paper compares the long wavelength components of gravity anomalies derived from satellite altimetry with ones from the new global gravity field model EIGEN-1S of the CHAMP within the same spatial resolution,based on 2-D Gauss filter.
This paper presents an approach to directly use the modified Poisson integral to derive Hotine function in which those harmonic terms are excluded.Finally,the application of Hotine formula to a local gravity field approximation over land or ocean areas is discussed.
The necessity and feasibility of GPS and INSAR data integration are analyzed.The error correction in INSAR data by GPS measurement s is presented,including orbit error,co registration error,phase unwrapping error,DEM creation error,temporal decorrelation,and tropospheric delay error.The intetgration of GPS and INSA R data in both time and spatial domains by interpolation and filtering is discussed.
The mathematical formal of the ECC is derived.The ECC for various disturbing accelerations which include the vertical acceleration,Eötvös correction,horizontal acceleration correction and free-air correction etc.are analyzed by using the real observations from one airborne gravimetry test.The accuracy requirements for the eccentrical distance and the attitude are also discussed in detail.
The datum transformation relationship between the dynamic height network and dynamic plane control network is introduced in this paper.And in turn,the dynamic space network,i,e.the transformation relationship for 4-dimension geodetic datum,is also discussed.
In accordance with GPS dada produced from "Crust Movement Observation Network of China",the current motin and deformation of the blocks and their boundaries in the continent of China are computed and analyzed,using "inverse DDA of a block system in the sphere coordinate".And making wavelet transformation for the observational sequences of GPS continuously tracing stations,we investigated approaches abstracting precursory information from the continuously observational sequences of GPS with analysis of earthquake events occurred.
The characters of the secular and long-period variations in the length of day and the harmonic coefficient J2 of geopotential were analyzed based on the recent observational result of the length of day,the result of J2 variations in the recent twenty years and the ancient astronomical result of the Earth rotation.Then the relation and difference between variations of the length of day and J2 were discussed according to the theory of the Earth rotation and gravity.Furthermore we stressed the importance of J2 and the integrated use of the length of day and J2 for geodynamics.
Recursive formulae without degree and order(n,m) are presented.Fast computation formulae of the non-central gravitational vector and gravity tensor are deduced and respective algorithms are proposed.The algorithms can fasten the computation time five times,compared to the conventional methods.
The national geo-spatial data reference frame was put forward for the modernization of geodetic datum of China.The higher requirement of the former coordinate datum,height datum and gravity datum was in dire need of improvement and update in modernization.This paper gives the basic idea in construction and the principle in solution.
The improvement of regional geoid is one of basic tasks of State Bureau of Surveying and Mapping.In 2003,the bureau did experiments in Jiangxi province,Zhejiang province and Fujian province.The authors give some discussions on geoid improvement in order to give help to others as reference.
The unreasonable distribution of GPS leveling height points may cause the estimated parameters unstable,which will accordingly affect the accuracy of the interpolated height anomaly.In order to obtain relatively stable result,this paper probes into a reducing dimension algorithm on ill-posed error equation.Essentially this method is a tailored-regularization algorithm.
An improved geoid model for Hong Kong,HKGEOID-2000 with 1km resolution,was developed with remove-restore approach and 1D-FFT technique.This geoid model,along with GPS ellipsoidal heights,is employed to determine the errors of the "orthometric heights" from purely trigonometric heighting in Hong Kong,yielding an RMS error of 0.102m and the standard deviation ±3.4cm.
According to the new generation of satellite exploring mission,this paper investigates the major pay loads of gravity exploring satellite.Based on the fundamental principle of gravity measurements,we derive the necessary satellite altitude,the accuracy requirements to be satisfied for the payloads,and the functional relationship between the highest resolution to be able to recover and the accuracies of the corresponding gravity field parameters.Finally,the authors calculate the indexes of the major measuring payloads of CHAMP,GRACE and GOCE satellites.
This paper discusses the role of refining geoid in the development of contemporary surveying and mapping,and considers that a gridded digital geoid model is really a reference frame in datum sense for orthometric or normal height measurement.The real resolution of the new generation quasi-geoid model CQG2000 in China is analysed in detail,and the accuracy estimates of the model is also described.In addition,the advanced level in geoid refinement abroad is briefly introduced,and the necessity,requirement and possible approach for further refining the quasi-geoid model in China are pointed out.
This paper puts forward the LS adjustment based on the homotopy arithmetic,deduces and constructes homotopy nonlinear LS model and its algorithms with nonlinear LS method.This method is an effective numerical method to solve the nonlinear equation.
The classical asymptotic expressions of load love numbers of Farrell(1972) is rederived out by using a different method,and then generalized to one order of magnitude more accurately.Using the more accurate expressions,we can reformulate the Legendre sums in the expression of the Green's functions to forms converging one order of magnitude faster,thus facilitating the computation of the Green's functions.
This paper presentes a new series of high-resolution earth's gravity field models DQM2000 computed by the method of regional integral correct ion with frequency weight and their accuracy comparison.Based on the OSU91A and EGM96 models and the regional mean gravity anomalies of 20'×20',15'×15',10'×10' and 5'×5'in China,the improved models DQM2000A,DQM2000B,DQM2000C and DQM2000D,whose complete degrees and orders are up to 540,720,1 080 and 2 160 respectively,are developed.
The tidal gravity data recorded with three LCR high precision spring gravimeters at stations Changcheng and Zhongshan in Antarctic are studied.The ocean loading problems are studied.The influence of the atmospheric pressure and temperature on gravity is discussed.The results indicate that the atmospheric gravity admittances are reduced with the increase of the signal frequency and may contain the inverse barometric effect.
We present a preliminary determination of crustal deformation based primarily on GPS measurements we made in Xinjiang from 1995 to 2002,combined with the data of continuous GPS data in Central Asia.The results show that the sites on the southern border of the Tianshan move at(15~19) mm/a to the NNE relative to the stable Eurasia plate.This rate increases to(20.9±0.6) mm/a at Yopurga,our southernmost site in the Tarim basin,located 35km to the southeast of the range front.A preliminary GPS Eurasia-Tarim Basin Euler vector of 36.5°±0.5°N,99.2°±1.1°E,0.525°±0.030°/Ma is determined.
Two basic observation equations for gravity field recovery are presented.The existing algorithms are classified on the angles of expression mode of transfer coefficients matrix from gravity field parameters to basic observations.A data processing method about kinematic/dynamic orbit determination and gravity field recovery is introduced.
The network layout,site choice,observation project,data-processing methods are introduced in this paper.And the method of jointly processing and analysis with two GPS network and multi-period observation is demonstrated by GPS technology.Plate conformation and movement in Xinjiang area and Tianshan area are studied.
Arithmetic and module-design in the DGPS Way software were introduced.The differential GPS based software package has been successfully used in the nationwide highway surveying in China.Arithmetic of differential GPS and carrier phase-aided code smoothing,recording of attribute-data,time synchronization between computer and GPS receiver,matching of terrestrial-object and coordinate stream were described in detail.
Within the Qinghai-Tibet Plateau,extensive E-W crustal extension is observed.Since this kind of E-W extension is not the consequence of global tectonics,other geodynamic process must be superimposed to collision and compression between Indian and Eurasia plates to be responsible for the E-W extension.