Loading...

Table of Content

    20 April 2014, Volume 43 Issue 4
    Iterative Solution of Regularization Based on Controlling Condition Number
    2014, 43(4):  331-336. 
    Asbtract ( )   HTML   PDF (1093KB) ( )  
    Related Articles | Metrics

    In geodesy and geophysics, many large-scale over-determined linear equations need to be solved which are often ill-conditioned. When the conjugate gradient method is used, their ill-conditioned effects to the solutions must be overcome, which is studied in this paper. By regularization ideas, the conjugate gradient method is improved; the regularization iterative solution based on controlling condition number is put forward. Firstly by constructing the interference source vector, a new equation is derived with ill-condition diminished greatly, which has the same solution to the original normal equation. Then the new equation is solved by conjugate gradient method. Finally the effectiveness of the new method is verified by some numerical experiments of airborne gravity downward to the earth surface. In the numerical experiments the new method is compared with LS, CG and Tikhonov methods, and its accuracy is the highest.

    Influence of altimetry errors on marine geopotential recovery
    2014, 43(4):  337-340. 
    Asbtract ( )   HTML   PDF (873KB) ( )  
    References | Related Articles | Metrics

    The influence of the altimetry errors on the marine geopotential recovery was studied. And the formulae for the altimetry stochastic errors transmission during the marine gravity anomalies prediction were presented. In the end, the predicted geopotential errors with seveal resolutions from 8 cm altimetry random error were simulated. The paper proposes some references for the Chinese altimetry satellite design in the future.

    The Non-singular Formula of Gauss Projection by Complex Numbers in Polar Regions
    2014, 43(4):  348-352. 
    Asbtract ( )   HTML   PDF (1565KB) ( )  
    Related Articles | Metrics

    Abstract: Based on expressions of Gauss projection by complex numbers, the conformal latitude by complex numbers was introduced to solve the singularity problem of isometric latitude in polar regions. Secondly, conformal colatitude by complex numbers was introduced on the basis of conformal latitude by complex numbers, with the polar point taken as the origin of coordinates in Gauss projection, the non-singular formula of Gauss projection in polar regions by complex numbers was set up. Finally, compared with traditional power series and expressions by complex numbers of Gauss projection, the non-singular formula proved to be highly accurate. The new expression of Gauss projection in polar regions could overcome imperfection of zonation of traditional Gauss projection, which makes Gauss Projection a uniform integrated form in polar regions.

    Earth eclipse status analysis of GEO IGSO and MEO
    2014, 43(4):  353-359. 
    Asbtract ( )   HTML   PDF (1293KB) ( )  
    Related Articles | Metrics

    To meet the need of earth eclipse time determination in satellite navigation system’s state switching and solar radiation pressure modeling with orbit determination, this paper analysed the difference of cylindrical and conical model in eclipse factor and umbra duration calculation for GEO, IGSO, MEO three types of navigation satellites. And then the number of days suffering earth eclipse in a years’ time and the umbra duration in one day are analysed in order to obtain the relationship between orbit elements and earth eclipse status.

    Adjustment Model and Colored Noise Reduction of Continuous Observation System
    Xue shuqiang Yuanxi Yang
    2014, 43(4):  360-365. 
    Asbtract ( )   HTML   PDF (892KB) ( )  
    References | Related Articles | Metrics

    Nowadays, surveying technique mainly relies on continuous earth observation systems. In practice, while the precision and the reliability of estimated parameters are seriously affected by colored noises, these colored noises contain a great amount of useful information to the earth science. On the one hand, the affection caused by these colored noises should be taken into account to the adjustment model, on the other hand, as useful signals these colored noises can be accurately identified and extracted by Fourier analysis. In this paper, a continuous adjustment model is introduced with respect to the colored noises, and then we generalize the traditional adjustment theory from the finite space to the infinite space so called as Hilbert space. This extension is to provide a new technique to perform the continuous observational system design, Fourier analysis as well as the parameter estimation. It shows that the Gramer’s determinant provides maximization criteria in the system optimization design as well as a rule in diagnosing the adjustment model. Related with the definition of the integral, the least squares solution of the continuous adjustment model becomes the limit of the traditional least squares solution in finite space. Moreover, the influence caused by the colored noises is systematic, but it can be eliminated by optimally designing the observational system and the observational scheme.

    A robust positioning algorithm with the modified M-estimation for multiple outliers
    2014, 43(4):  366-371. 
    Asbtract ( )   HTML   PDF (1067KB) ( )  
    Related Articles | Metrics

    The possibility of multiple outliers should not be neglected in measurements for the increment number of the navigation satellites, and the RAIM based on the single-outlier hypothesis can not provide effective restraining against multiple outliers . The robust estimation is focused widely. A robust positioning algorithm is presented for resisting multiple outliers which make the traditional M-estimator ineffective. The robustness can be improved by the modified positioning algorithm. To handle the biased convergence problem, the robust estimate of the initial values is realized by modifying the S-estimation with available satellite number in real time. Positioning results of the actual GPS measurements show that the proposed method resists multiple outliers effectively.

    Automatic registration of urban aerial images with airborne LiDAR points based on line-point similarity invariants
    2014, 43(4):  372-379. 
    Asbtract ( )   HTML   PDF (3614KB) ( )  
    Related Articles | Metrics
    Automatic Tie Point Matching of Aerial Images Acquired by LiDAR System
    2014, 43(4):  380-388. 
    Asbtract ( )   HTML   PDF (1561KB) ( )  
    References | Related Articles | Metrics

    Aerial images tie points matching is conducted with the assistance of LiDAR points and POS data. Fast searching algorithm for obtaining conjugate point in correlation matching is devised. An automatic boresight misalignment calibration method based on virtual ground control points is adopted, on base of which the searching range of image matching is adaptively determined. The experimental results indicate that the fast searching algorithm proposed in this paper can reduce 20% of the matching time while ensuring the matching correctness. The camera boresight misalignment calibration method can effectively refine the accuracy of exterior orientation elements of images derived from POS data, and significantly improve the precision of predicted point position for tie points matching. The matching algorithm proposed in this paper can process multi-scale, multi-angle, cross-flight aerial images and obtain a high matching accuracy.

    Comparative study of plane and stereo block adjustment for satellite imagery
    2014, 43(4):  389-395. 
    Asbtract ( )   HTML   PDF (1278KB) ( )  
    Related Articles | Metrics

    In response to the problem that block adjustment for satellite images cannot be solved with weak convergence geometric conditions, this paper proposed a plane block adjustment method that utilizing DEM as height constraint plane block adjustment method to improve the targeting precision of imagery. First, rational function model (RFM) with affine transformation is selected as the mathematical model of the satellite image plane block adjustment. Second, to update the ground coordinates of Tie Points (TPs), the plane coordinates of TPs were only solved in the adjustment process. Elevation values obtained using DEM interpolation. Finally, the plane coordinates of all TPs and orientation parameters of all satellite images were solved through plane block adjustment with a few Ground Control Points (GCPs). ZY-3 nadir images of two regions were tested for plane block adjustment and ZY-3 forward-nadir-back images of the same two regions were tested for stereo block adjustment. Comparison indicates that almost the same accuracy can be obtained by plane block adjustment support with 1:50000 DEM and stereo block adjustment for ZY-3 images. For ZY-3 nadir images, when global DEM with 1km grid and SRTM with 90m grid replaced 1:50000 DEM as elevation control, accuracy of plane block adjustment almost no loss. Ultimately, the test results proved the effectiveness and feasibility of the plane block adjustment method.

    A Qualitative Model of Directional Relations Based on Topological Constraint
    2014, 43(4):  396-403. 
    Asbtract ( )   HTML   PDF (1141KB) ( )  
    References | Related Articles | Metrics

    Directional relation is one of the most important characters of spatial objects and is useful for spatial retrieval, analysis and reasoning. For line and area reference objects, the directional reference is distinct in the different topological area. However, existing models ignore this difference and represent the direction relations based on the same reference in the whole region of MBR (minimum bounding rectangle). To overcome the problems of direction-relation representation in the MBR of reference object, this paper extend the model of direction-relation matrix and propose a new model based on topological restraint. The new model, called the hierarchical direction-relation matrix based on topological restraint, retains three direction-matrixes with empty and non-empty tiles, which record direction-relation codes for three topological regions. The new qualitative model is based on the topological restraints to direction-relation definition, in which (1) the minimum bounding rectangle of reference object is decomposed into three topological regions (i.e. exterior, boundary and interior); (2) topological references are defined to discribe the alteration of directional reference in three topological regions; (3) three direction-relation matrixes (i.e. exterior, boudary, interior direction-relation matrix) are utilized to represent the directional relations of three topological regions; and (4) a hierarchical calculative approach is proposed for discription of direction relations between different topolical spatial objects to improve the computational efficiency. The new model overcomes the discription difficulty of directional relations bewteen objects of complex topological relations and improve the accuracy and veracity of direction relations models.

    Matching Algorithm for Chinese Place Names by Similarity with Semantics of General Names for Places into Consideration
    2014, 43(4):  404-410. 
    Asbtract ( )   HTML   PDF (963KB) ( )  
    References | Related Articles | Metrics

    Matching of Place Names is one of the key issues in geographic information retrieval, integration and update for multi-source geospatial data. According to the constitute characteristics for Chinese Place Names and relations between general names for places and its types; Ontology knowledge base for general names for places has been established, based on which semantic of Place Names is used as an important indicator for matching of Place Names by their similarity. Aiming at overcoming the shorts of queries by literals or geospatial data for place names, we propose a new matching algorithm and query strategy for Chinese Place Names taking both similarities of special names and general names for places into consideration. The method simulates human cognitive habits, in which the weights of similarity for special names and general names for places are set dynamically according to the degree of semantic similarity by a monotonic function relationship. The final composite similarity index for Place Names is weighted average for similarities of special names and general names for Places. Based on the model above, the strategy and flow has been put forward, which enhances the theoretical basis and completeness of matching algorithm for Chinese Place Names by using semantic knowledge from general names for places, and it thereby improves the accuracy of the matching algorithm. The experimental results show that the matching model is consistent with human cognitive habits, and further demonstrate the rationality and effectiveness of this method.

    Increments Recognition and Calculation Considering the Constraints of Spatio-temporal Boundaries
    2014, 43(4):  411-418. 
    Asbtract ( )   HTML   PDF (1127KB) ( )  
    Related Articles | Metrics

    Spurious increments caused by spatio-temporal boundaries exist inevitably in the results of increments recognition with two database, which has seriously reduced the accuracy of the incremental information. However, the current methods cannot distinct the spurious increments appeared as slivers caused by spatio-temporal boundaries, and the true increments caused by the slivers entities. Aim to solve this problem, a new method of increments recognition and calculation is proposed in this paper. And firstly, distance between spatio-temporal boundaries is used to quantified the inconsistency of spatio-temporal boundaries, and then the distance is compared with the updating threshold to distinguish the spurious increments and the true increments. Finally, the method is applied to the incements recognition of spatial database at the scale of 1: 50 000. The experimental results show that our method is valid and has stronger practicality.

    Multi-Scale Areal Feature Matching Approach Based On Root Mean Square Error And Neighbouring Relation
    2014, 43(4):  419-425. 
    Asbtract ( )   HTML   PDF (1133KB) ( )  
    References | Related Articles | Metrics

    Map object matching as an indispensable process in spatial data integration and updating has important researching significance. Root Mean Square Error (RMSE) as a numerical indicator that measures map accuracy and quality , its range is as one of the important standards in mapping and cartography generalization, and commonly used to balance the quality of spatial data, The data of different scale or sources are varying in size and threshold of the RMSE. Polygons occupy a much proportion in a map, this paper introduces the RMSE in the process of areal feature matching, combined with the clustering algorithm of adjacent Polygon to match areal feature. It can effectively solve the problems for dertermining the threshold and many-to-many relationship in the multi-scale spatial areal feature matching, the experimental results show that this method is stability and reliability.

    Block Aggregation Optimization Model for Grid Pattern Maintenance in Urban Network
    2014, 43(4):  426-434. 
    Asbtract ( )   HTML   PDF (2190KB) ( )  
    References | Related Articles | Metrics

    In this article we present a mixed-integer programming model for urban blocks aggregation, aiming to maintain grid pattern after road selection. This model firstly defines the objective function to quantify the grid pattern maintenance, composed of four evaluations namely compactness, hierarchy, arrangement consistence and aggregating directionality. Secondly, four constraints are built ensuring effective and efficient aggregation for the target scale, including aggregating scale, stroke deletion, conjoint aggregation and connectivity. Finally, the whole urban road network are divided in to several subregions with high-level roads, and the aggregation problem are decomposed into independent subinstances to model to maintain both the skeleton and grid patterns of the urban. The mixed-integer programming model can be solved by optimization software CPLEX. We tested our method for a dataset of the official German topographic database ATKIS with input scale 1:25,000 and output scale 1:100,000. We also compare results of this model with existing map data. These tests allow us to conclude that our optimization method yields high-quality results for both global and local patterns maintenance.

    On Key Technologies of Data Processing for Air-sea Gravity Surveys
    2014, 43(4):  435-435. 
    Asbtract ( )   HTML   PDF (645KB) ( )  
    Related Articles | Metrics

    On Key Technologies of Data Processing for Air-sea Gravity Surveys

    Research on Key Technology and Application of GAT High-accuracy Magnetic Suspension Gyro Station
    2014, 43(4):  436-436. 
    Asbtract ( )   HTML   PDF (676KB) ( )  
    Related Articles | Metrics

    Gyro Station is an important product of inertial navigation technology, it plays an irreplaceable role in the field of national defense and national economy. Therefore, with our own independent intellectual property developed high-precise Gyro Station will have very important practical significance and practical value. In this article, we take the our self-developed GAT high-precision magnetic levitation gyro station directional system as research object to discuss the gyro directional system design of maglev supporting system, key gyro's north seeking technology, characteristics of sampling data and its application research.

    The Monitoring of Antarctic snow and ice changes from the multiple-sources Remote Sensing data
    2014, 43(4):  437-437. 
    Asbtract ( )   HTML   PDF (655KB) ( )  
    Related Articles | Metrics
    Theory and Methods of Dimensionality Reduction using Manifold Learning for Hyperspectral Imagery
    2014, 43(4):  439-439. 
    Asbtract ( )   HTML   PDF (673KB) ( )  
    Related Articles | Metrics